[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
@@ -274,6 +274,51 @@ static IterableExpansionStmtData
TryBuildIterableExpansionStmtInitializer(
return Data;
}
+static StmtResult BuildDestructuringDecompositionDecl(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
Sirraide wrote:
So at least when it comes to this file, `VarIsConstexpr` is used for more than
just deciding what expression evaluation context to push (e.g. it’s used to
make the `__range` variable `constexpr` iff it is declared `constexpr`), and I
feel like passing the expression evaluation context enum as a parameter would
make it a lot less obvious as to what’s going on there
https://github.com/llvm/llvm-project/pull/169685
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[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide updated
https://github.com/llvm/llvm-project/pull/169685
>From e4abcd3e0fa975ea764e57a39f89bdf43f18bf67 Mon Sep 17 00:00:00 2001
From: Sirraide
Date: Wed, 26 Nov 2025 17:00:57 +0100
Subject: [PATCH] [Clang] [C++26] Expansion Statements (Part 6)
---
.../clang/Basic/DiagnosticSemaKinds.td| 2 +
clang/lib/Sema/SemaExpand.cpp | 111 +-
clang/lib/Sema/TreeTransform.h| 26 +++-
3 files changed, 130 insertions(+), 9 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 9142afb95b89d..7f6fd47b3bb71 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3730,6 +3730,8 @@ def err_conflicting_codeseg_attribute : Error<
def warn_duplicate_codeseg_attribute : Warning<
"duplicate code segment specifiers">, InGroup;
+def err_expansion_stmt_invalid_init : Error<
+ "cannot expand expression of type %0">;
def err_expansion_stmt_vla : Error<
"cannot expand variable length array type %0">;
def err_expansion_stmt_incomplete : Error<
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index f821f73cb1e55..27878377f934f 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -86,7 +86,7 @@ static bool HasDependentSize(const DeclContext *CurContext,
return true;
case CXXExpansionStmtPattern::ExpansionStmtKind::Destructuring:
-llvm_unreachable("TODO");
+return false;
}
llvm_unreachable("invalid pattern kind");
@@ -274,6 +274,51 @@ static IterableExpansionStmtData
TryBuildIterableExpansionStmtInitializer(
return Data;
}
+static StmtResult BuildDestructuringDecompositionDecl(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx);
+
+ // The declarations should be attached to the parent decl context.
+ Sema::ContextRAII CtxGuard(S, S.CurContext->getParent(),
+ /*NewThis=*/false);
+
+ UnsignedOrNone Arity =
+ S.GetDecompositionElementCount(ExpansionInitializer->getType(),
ColonLoc);
+
+ if (!Arity) {
+S.Diag(ExpansionInitializer->getBeginLoc(),
+ diag::err_expansion_stmt_invalid_init)
+<< ExpansionInitializer->getType()
+<< ExpansionInitializer->getSourceRange();
+return StmtError();
+ }
+
+ QualType AutoRRef = S.Context.getAutoRRefDeductType();
+ SmallVector Bindings;
+ for (unsigned I = 0; I < *Arity; ++I)
+Bindings.push_back(BindingDecl::Create(
+S.Context, S.CurContext, ColonLoc,
+S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)),
+AutoRRef));
+
+ TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef);
+ auto *DD =
+ DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc,
+AutoRRef, TSI, SC_Auto, Bindings);
+
+ if (VarIsConstexpr)
+DD->setConstexpr(true);
+
+ S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD,
LifetimeExtendTemps);
+ S.AddInitializerToDecl(DD, ExpansionInitializer, false);
+ return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc);
+}
+
CXXExpansionStmtDecl *
Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
SourceLocation TemplateKWLoc) {
@@ -435,8 +480,59 @@ StmtResult
Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
Data.IterDecl, LParenLoc, ColonLoc, RParenLoc);
}
- Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
- return StmtError();
+ // If not, try destructuring.
+ StmtResult DecompDeclStmt = BuildDestructuringDecompositionDecl(
+ *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(),
+ LifetimeExtendTemps);
+ if (DecompDeclStmt.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ auto *DS = DecompDeclStmt.getAs();
+ auto *DD = cast(DS->getSingleDecl());
+ if (DD->isInvalidDecl())
+return StmtError();
+
+ // Synthesise an InitListExpr to store the bindings; this essentially lets us
+ // desugar the expansion of a destructuring expansion statement to that of an
+ // enumerating expansion statement.
+ SmallVector Bindings;
+ for (BindingDecl *BD : DD->bindings()) {
+Expr *Element = BuildDeclRefExpr(BD, BD->getType().getNonReferenceType(),
+ VK_LValue, ColonLoc);
+
+// CWG 3149: If the expansion-initializer is an lvalue, then vi is ui;
+// otherwise, vi is static_cast(ui).
+if (!ExpansionInitializer->isLValue()) {
+ QualType Ty =
+ BuildReferenceType(getDecltypeForExpr
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide updated
https://github.com/llvm/llvm-project/pull/169685
>From 7de4b68bbe9ccdb391c3afb8cabc3df308384d52 Mon Sep 17 00:00:00 2001
From: Sirraide
Date: Wed, 26 Nov 2025 17:00:57 +0100
Subject: [PATCH] [Clang] [C++26] Expansion Statements (Part 6)
---
.../clang/Basic/DiagnosticSemaKinds.td| 2 +
clang/lib/Sema/SemaExpand.cpp | 109 +-
clang/lib/Sema/TreeTransform.h| 26 -
3 files changed, 128 insertions(+), 9 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 9142afb95b89d..7f6fd47b3bb71 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3730,6 +3730,8 @@ def err_conflicting_codeseg_attribute : Error<
def warn_duplicate_codeseg_attribute : Warning<
"duplicate code segment specifiers">, InGroup;
+def err_expansion_stmt_invalid_init : Error<
+ "cannot expand expression of type %0">;
def err_expansion_stmt_vla : Error<
"cannot expand variable length array type %0">;
def err_expansion_stmt_incomplete : Error<
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index c51b9df082352..16028812dab41 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -86,7 +86,7 @@ static bool HasDependentSize(const DeclContext *CurContext,
return true;
case CXXExpansionStmtPattern::ExpansionStmtKind::Destructuring:
-llvm_unreachable("TODO");
+return false;
}
llvm_unreachable("invalid pattern kind");
@@ -284,6 +284,51 @@ static IterableExpansionStmtData
TryBuildIterableExpansionStmtInitializer(
return Data;
}
+static StmtResult BuildDestructuringDecompositionDecl(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx);
+
+ // The declarations should be attached to the parent decl context.
+ Sema::ContextRAII CtxGuard(S, S.CurContext->getParent(),
+ /*NewThis=*/false);
+
+ UnsignedOrNone Arity =
+ S.GetDecompositionElementCount(ExpansionInitializer->getType(),
ColonLoc);
+
+ if (!Arity) {
+S.Diag(ExpansionInitializer->getBeginLoc(),
+ diag::err_expansion_stmt_invalid_init)
+<< ExpansionInitializer->getType()
+<< ExpansionInitializer->getSourceRange();
+return StmtError();
+ }
+
+ QualType AutoRRef = S.Context.getAutoRRefDeductType();
+ SmallVector Bindings;
+ for (unsigned I = 0; I < *Arity; ++I)
+Bindings.push_back(BindingDecl::Create(
+S.Context, S.CurContext, ColonLoc,
+S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)),
+AutoRRef));
+
+ TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef);
+ auto *DD =
+ DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc,
+AutoRRef, TSI, SC_Auto, Bindings);
+
+ if (VarIsConstexpr)
+DD->setConstexpr(true);
+
+ S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD,
LifetimeExtendTemps);
+ S.AddInitializerToDecl(DD, ExpansionInitializer, false);
+ return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc);
+}
+
CXXExpansionStmtDecl *
Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
SourceLocation TemplateKWLoc) {
@@ -445,8 +490,57 @@ StmtResult
Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
Data.IterDecl, LParenLoc, ColonLoc, RParenLoc);
}
- Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
- return StmtError();
+ // If not, try destructuring.
+ StmtResult DecompDeclStmt = BuildDestructuringDecompositionDecl(
+ *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(),
+ LifetimeExtendTemps);
+ if (DecompDeclStmt.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ auto *DS = DecompDeclStmt.getAs();
+ auto *DD = cast(DS->getSingleDecl());
+ if (DD->isInvalidDecl())
+return StmtError();
+
+ // Synthesise an InitListExpr to store the bindings; this essentially lets us
+ // desugar the expansion of a destructuring expansion statement to that of an
+ // enumerating expansion statement.
+ SmallVector Bindings;
+ for (BindingDecl *BD : DD->bindings()) {
+Expr *Element = BuildDeclRefExpr(BD, BD->getType().getNonReferenceType(),
+ VK_LValue, ColonLoc);
+
+// CWG 3149: If the expansion-initializer is an lvalue, then vi is ui;
+// otherwise, vi is static_cast(ui).
+if (!ExpansionInitializer->isLValue()) {
+ TypeSourceInfo *TSI = Context.getTrivialTypeSourceInfo(
+
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide updated
https://github.com/llvm/llvm-project/pull/169685
>From ae93fdd0b4999283f4002dddaade64d8bfadb160 Mon Sep 17 00:00:00 2001
From: Sirraide
Date: Wed, 26 Nov 2025 17:00:57 +0100
Subject: [PATCH] [Clang] [C++26] Expansion Statements (Part 6)
---
.../clang/Basic/DiagnosticSemaKinds.td| 2 +
clang/lib/Sema/SemaExpand.cpp | 110 +-
clang/lib/Sema/TreeTransform.h| 55 +++--
3 files changed, 151 insertions(+), 16 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 9142afb95b89d..7f6fd47b3bb71 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3730,6 +3730,8 @@ def err_conflicting_codeseg_attribute : Error<
def warn_duplicate_codeseg_attribute : Warning<
"duplicate code segment specifiers">, InGroup;
+def err_expansion_stmt_invalid_init : Error<
+ "cannot expand expression of type %0">;
def err_expansion_stmt_vla : Error<
"cannot expand variable length array type %0">;
def err_expansion_stmt_incomplete : Error<
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index ca286854b4002..231f6e657e55e 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -85,7 +85,7 @@ static bool HasDependentSize(const CXXExpansionStmtPattern
*Pattern) {
return true;
case CXXExpansionStmtPattern::ExpansionStmtKind::Destructuring:
-llvm_unreachable("TODO");
+return false;
}
llvm_unreachable("invalid pattern kind");
@@ -281,6 +281,52 @@ TryBuildIterableExpansionStmtInitializer(Sema &S, Expr
*ExpansionInitializer,
return Data;
}
+static StmtResult BuildDestructuringDecompositionDecl(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx);
+
+ // The declarations should be attached to the parent decl context.
+ Sema::ContextRAII CtxGuard(
+ S, S.CurContext->getEnclosingNonExpansionStatementContext(),
+ /*NewThis=*/false);
+
+ UnsignedOrNone Arity =
+ S.GetDecompositionElementCount(ExpansionInitializer->getType(),
ColonLoc);
+
+ if (!Arity) {
+S.Diag(ExpansionInitializer->getBeginLoc(),
+ diag::err_expansion_stmt_invalid_init)
+<< ExpansionInitializer->getType()
+<< ExpansionInitializer->getSourceRange();
+return StmtError();
+ }
+
+ QualType AutoRRef = S.Context.getAutoRRefDeductType();
+ SmallVector Bindings;
+ for (unsigned I = 0; I < *Arity; ++I)
+Bindings.push_back(BindingDecl::Create(
+S.Context, S.CurContext, ColonLoc,
+S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)),
+AutoRRef));
+
+ TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef);
+ auto *DD =
+ DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc,
+AutoRRef, TSI, SC_Auto, Bindings);
+
+ if (VarIsConstexpr)
+DD->setConstexpr(true);
+
+ S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD,
LifetimeExtendTemps);
+ S.AddInitializerToDecl(DD, ExpansionInitializer, false);
+ return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc);
+}
+
CXXExpansionStmtDecl *
Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
SourceLocation TemplateKWLoc) {
@@ -442,8 +488,57 @@ StmtResult
Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
Data.EndDecl, Data.IterDecl, LParenLoc, ColonLoc, RParenLoc);
}
- Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
- return StmtError();
+ // If not, try destructuring.
+ StmtResult DecompDeclStmt = BuildDestructuringDecompositionDecl(
+ *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(),
+ LifetimeExtendTemps);
+ if (DecompDeclStmt.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ auto *DS = DecompDeclStmt.getAs();
+ auto *DD = cast(DS->getSingleDecl());
+ if (DD->isInvalidDecl())
+return StmtError();
+
+ // Synthesise an InitListExpr to store the bindings; this essentially lets us
+ // desugar the expansion of a destructuring expansion statement to that of an
+ // enumerating expansion statement.
+ SmallVector Bindings;
+ for (BindingDecl *BD : DD->bindings()) {
+Expr *Element = BuildDeclRefExpr(BD, BD->getType().getNonReferenceType(),
+ VK_LValue, ColonLoc);
+
+// CWG 3149: If the expansion-initializer is an lvalue, then vi is ui;
+// otherwise, vi is static_cast(ui).
+if (!ExpansionInitializer->isLValue()) {
+ TypeSourceI
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide updated
https://github.com/llvm/llvm-project/pull/169685
>From ae93fdd0b4999283f4002dddaade64d8bfadb160 Mon Sep 17 00:00:00 2001
From: Sirraide
Date: Wed, 26 Nov 2025 17:00:57 +0100
Subject: [PATCH] [Clang] [C++26] Expansion Statements (Part 6)
---
.../clang/Basic/DiagnosticSemaKinds.td| 2 +
clang/lib/Sema/SemaExpand.cpp | 110 +-
clang/lib/Sema/TreeTransform.h| 55 +++--
3 files changed, 151 insertions(+), 16 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 9142afb95b89d..7f6fd47b3bb71 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3730,6 +3730,8 @@ def err_conflicting_codeseg_attribute : Error<
def warn_duplicate_codeseg_attribute : Warning<
"duplicate code segment specifiers">, InGroup;
+def err_expansion_stmt_invalid_init : Error<
+ "cannot expand expression of type %0">;
def err_expansion_stmt_vla : Error<
"cannot expand variable length array type %0">;
def err_expansion_stmt_incomplete : Error<
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index ca286854b4002..231f6e657e55e 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -85,7 +85,7 @@ static bool HasDependentSize(const CXXExpansionStmtPattern
*Pattern) {
return true;
case CXXExpansionStmtPattern::ExpansionStmtKind::Destructuring:
-llvm_unreachable("TODO");
+return false;
}
llvm_unreachable("invalid pattern kind");
@@ -281,6 +281,52 @@ TryBuildIterableExpansionStmtInitializer(Sema &S, Expr
*ExpansionInitializer,
return Data;
}
+static StmtResult BuildDestructuringDecompositionDecl(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx);
+
+ // The declarations should be attached to the parent decl context.
+ Sema::ContextRAII CtxGuard(
+ S, S.CurContext->getEnclosingNonExpansionStatementContext(),
+ /*NewThis=*/false);
+
+ UnsignedOrNone Arity =
+ S.GetDecompositionElementCount(ExpansionInitializer->getType(),
ColonLoc);
+
+ if (!Arity) {
+S.Diag(ExpansionInitializer->getBeginLoc(),
+ diag::err_expansion_stmt_invalid_init)
+<< ExpansionInitializer->getType()
+<< ExpansionInitializer->getSourceRange();
+return StmtError();
+ }
+
+ QualType AutoRRef = S.Context.getAutoRRefDeductType();
+ SmallVector Bindings;
+ for (unsigned I = 0; I < *Arity; ++I)
+Bindings.push_back(BindingDecl::Create(
+S.Context, S.CurContext, ColonLoc,
+S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)),
+AutoRRef));
+
+ TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef);
+ auto *DD =
+ DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc,
+AutoRRef, TSI, SC_Auto, Bindings);
+
+ if (VarIsConstexpr)
+DD->setConstexpr(true);
+
+ S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD,
LifetimeExtendTemps);
+ S.AddInitializerToDecl(DD, ExpansionInitializer, false);
+ return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc);
+}
+
CXXExpansionStmtDecl *
Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
SourceLocation TemplateKWLoc) {
@@ -442,8 +488,57 @@ StmtResult
Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
Data.EndDecl, Data.IterDecl, LParenLoc, ColonLoc, RParenLoc);
}
- Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
- return StmtError();
+ // If not, try destructuring.
+ StmtResult DecompDeclStmt = BuildDestructuringDecompositionDecl(
+ *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(),
+ LifetimeExtendTemps);
+ if (DecompDeclStmt.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ auto *DS = DecompDeclStmt.getAs();
+ auto *DD = cast(DS->getSingleDecl());
+ if (DD->isInvalidDecl())
+return StmtError();
+
+ // Synthesise an InitListExpr to store the bindings; this essentially lets us
+ // desugar the expansion of a destructuring expansion statement to that of an
+ // enumerating expansion statement.
+ SmallVector Bindings;
+ for (BindingDecl *BD : DD->bindings()) {
+Expr *Element = BuildDeclRefExpr(BD, BD->getType().getNonReferenceType(),
+ VK_LValue, ColonLoc);
+
+// CWG 3149: If the expansion-initializer is an lvalue, then vi is ui;
+// otherwise, vi is static_cast(ui).
+if (!ExpansionInitializer->isLValue()) {
+ TypeSourceI
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/zwuis edited https://github.com/llvm/llvm-project/pull/169685 ___ llvm-branch-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/zwuis edited https://github.com/llvm/llvm-project/pull/169685 ___ llvm-branch-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide updated
https://github.com/llvm/llvm-project/pull/169685
>From 07d55ff90ee97ed9393f5b2d0aeadc43f0fc196f Mon Sep 17 00:00:00 2001
From: Sirraide
Date: Wed, 26 Nov 2025 17:00:57 +0100
Subject: [PATCH 1/6] [Clang] [C++26] Expansion Statements (Part 6)
---
.../clang/Basic/DiagnosticSemaKinds.td| 2 +
clang/include/clang/Sema/Sema.h | 3 +
clang/lib/Sema/SemaExpand.cpp | 100 +-
clang/lib/Sema/TreeTransform.h| 81 ++
4 files changed, 162 insertions(+), 24 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index a92a3a6a7c331..208c885909b00 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3712,6 +3712,8 @@ def err_conflicting_codeseg_attribute : Error<
def warn_duplicate_codeseg_attribute : Warning<
"duplicate code segment specifiers">, InGroup;
+def err_expansion_stmt_invalid_init : Error<
+ "cannot expand expression of type %0">;
def err_expansion_stmt_vla : Error<
"cannot expand variable length array type %0">;
def err_expansion_stmt_incomplete : Error<
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 0adc570c73011..409e1d4e1b8ae 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -15713,6 +15713,9 @@ class Sema final : public SemaBase {
ExprResult BuildCXXExpansionSelectExpr(InitListExpr *Range, Expr *Idx);
+ ExprResult BuildCXXDestructuringExpansionSelectExpr(DecompositionDecl *DD,
+ Expr *Idx);
+
std::optional
ComputeExpansionSize(CXXExpansionStmtPattern *Expansion);
///@}
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index 40891e96e97de..315a4bdfd3a6c 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -220,6 +220,52 @@ TryBuildIterableExpansionStmtInitializer(Sema &S, Expr
*ExpansionInitializer,
return Data;
}
+static StmtResult BuildDestructuringCXXExpansionStmt(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx);
+
+ // The declarations should be attached to the parent decl context.
+ Sema::ContextRAII CtxGuard(
+ S, S.CurContext->getEnclosingNonExpansionStatementContext(),
+ /*NewThis=*/false);
+
+ UnsignedOrNone Arity =
+ S.GetDecompositionElementCount(ExpansionInitializer->getType(),
ColonLoc);
+
+ if (!Arity) {
+S.Diag(ExpansionInitializer->getBeginLoc(),
+ diag::err_expansion_stmt_invalid_init)
+<< ExpansionInitializer->getType()
+<< ExpansionInitializer->getSourceRange();
+return StmtError();
+ }
+
+ QualType AutoRRef = S.Context.getAutoRRefDeductType();
+ SmallVector Bindings;
+ for (unsigned I = 0; I < *Arity; ++I)
+Bindings.push_back(BindingDecl::Create(
+S.Context, S.CurContext, ColonLoc,
+S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)),
+AutoRRef));
+
+ TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef);
+ auto *DD =
+ DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc,
+AutoRRef, TSI, SC_Auto, Bindings);
+
+ if (VarIsConstexpr)
+DD->setConstexpr(true);
+
+ S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD,
LifetimeExtendTemps);
+ S.AddInitializerToDecl(DD, ExpansionInitializer, false);
+ return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc);
+}
+
CXXExpansionStmtDecl *
Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
SourceLocation TemplateKWLoc) {
@@ -368,8 +414,31 @@ StmtResult
Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
Data.EndDecl, LParenLoc, ColonLoc, RParenLoc);
}
- Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
- return StmtError();
+ // If not, try destructuring.
+ StmtResult DecompDeclStmt = BuildDestructuringCXXExpansionStmt(
+ *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(),
+ LifetimeExtendTemps);
+ if (DecompDeclStmt.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ auto *DS = DecompDeclStmt.getAs();
+ auto *DD = cast(DS->getSingleDecl());
+ if (DD->isInvalidDecl())
+return StmtError();
+
+ ExprResult Select = BuildCXXDestructuringExpansionSelectExpr(DD, Index);
+ if (Select.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ if (FinaliseExpansionVar(*this, ExpansionVar, Select))
+return StmtE
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide updated
https://github.com/llvm/llvm-project/pull/169685
>From 07d55ff90ee97ed9393f5b2d0aeadc43f0fc196f Mon Sep 17 00:00:00 2001
From: Sirraide
Date: Wed, 26 Nov 2025 17:00:57 +0100
Subject: [PATCH 1/6] [Clang] [C++26] Expansion Statements (Part 6)
---
.../clang/Basic/DiagnosticSemaKinds.td| 2 +
clang/include/clang/Sema/Sema.h | 3 +
clang/lib/Sema/SemaExpand.cpp | 100 +-
clang/lib/Sema/TreeTransform.h| 81 ++
4 files changed, 162 insertions(+), 24 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index a92a3a6a7c331..208c885909b00 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3712,6 +3712,8 @@ def err_conflicting_codeseg_attribute : Error<
def warn_duplicate_codeseg_attribute : Warning<
"duplicate code segment specifiers">, InGroup;
+def err_expansion_stmt_invalid_init : Error<
+ "cannot expand expression of type %0">;
def err_expansion_stmt_vla : Error<
"cannot expand variable length array type %0">;
def err_expansion_stmt_incomplete : Error<
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 0adc570c73011..409e1d4e1b8ae 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -15713,6 +15713,9 @@ class Sema final : public SemaBase {
ExprResult BuildCXXExpansionSelectExpr(InitListExpr *Range, Expr *Idx);
+ ExprResult BuildCXXDestructuringExpansionSelectExpr(DecompositionDecl *DD,
+ Expr *Idx);
+
std::optional
ComputeExpansionSize(CXXExpansionStmtPattern *Expansion);
///@}
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index 40891e96e97de..315a4bdfd3a6c 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -220,6 +220,52 @@ TryBuildIterableExpansionStmtInitializer(Sema &S, Expr
*ExpansionInitializer,
return Data;
}
+static StmtResult BuildDestructuringCXXExpansionStmt(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx);
+
+ // The declarations should be attached to the parent decl context.
+ Sema::ContextRAII CtxGuard(
+ S, S.CurContext->getEnclosingNonExpansionStatementContext(),
+ /*NewThis=*/false);
+
+ UnsignedOrNone Arity =
+ S.GetDecompositionElementCount(ExpansionInitializer->getType(),
ColonLoc);
+
+ if (!Arity) {
+S.Diag(ExpansionInitializer->getBeginLoc(),
+ diag::err_expansion_stmt_invalid_init)
+<< ExpansionInitializer->getType()
+<< ExpansionInitializer->getSourceRange();
+return StmtError();
+ }
+
+ QualType AutoRRef = S.Context.getAutoRRefDeductType();
+ SmallVector Bindings;
+ for (unsigned I = 0; I < *Arity; ++I)
+Bindings.push_back(BindingDecl::Create(
+S.Context, S.CurContext, ColonLoc,
+S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)),
+AutoRRef));
+
+ TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef);
+ auto *DD =
+ DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc,
+AutoRRef, TSI, SC_Auto, Bindings);
+
+ if (VarIsConstexpr)
+DD->setConstexpr(true);
+
+ S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD,
LifetimeExtendTemps);
+ S.AddInitializerToDecl(DD, ExpansionInitializer, false);
+ return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc);
+}
+
CXXExpansionStmtDecl *
Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
SourceLocation TemplateKWLoc) {
@@ -368,8 +414,31 @@ StmtResult
Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
Data.EndDecl, LParenLoc, ColonLoc, RParenLoc);
}
- Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
- return StmtError();
+ // If not, try destructuring.
+ StmtResult DecompDeclStmt = BuildDestructuringCXXExpansionStmt(
+ *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(),
+ LifetimeExtendTemps);
+ if (DecompDeclStmt.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ auto *DS = DecompDeclStmt.getAs();
+ auto *DD = cast(DS->getSingleDecl());
+ if (DD->isInvalidDecl())
+return StmtError();
+
+ ExprResult Select = BuildCXXDestructuringExpansionSelectExpr(DD, Index);
+ if (Select.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ if (FinaliseExpansionVar(*this, ExpansionVar, Select))
+return StmtE
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
github-actions[bot] wrote:
:warning: C/C++ code formatter, clang-format found issues in your code.
:warning:
You can test this locally with the following command:
``bash
git-clang-format --diff origin/main HEAD --extensions h,cpp --
clang/lib/Sema/SemaExpand.cpp clang/lib/Sema/TreeTransform.h
--diff_from_common_commit
``
:warning:
The reproduction instructions above might return results for more than one PR
in a stack if you are using a stacked PR workflow. You can limit the results by
changing `origin/main` to the base branch/commit you want to compare against.
:warning:
View the diff from clang-format here.
``diff
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index 6fa1ad985..daea18321 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -438,8 +438,7 @@ StmtResult Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
}
ExprResult Select = BuildCXXExpansionSelectExpr(
- new (Context) InitListExpr(Context, ColonLoc, Bindings, ColonLoc),
- Index);
+ new (Context) InitListExpr(Context, ColonLoc, Bindings, ColonLoc),
Index);
if (Select.isInvalid()) {
ActOnInitializerError(ExpansionVar);
``
https://github.com/llvm/llvm-project/pull/169685
___
llvm-branch-commits mailing list
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[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide updated
https://github.com/llvm/llvm-project/pull/169685
>From e3c61804686c4239d6ad53d4170ccb2563dac0cd Mon Sep 17 00:00:00 2001
From: Sirraide
Date: Wed, 26 Nov 2025 17:00:57 +0100
Subject: [PATCH 1/6] [Clang] [C++26] Expansion Statements (Part 6)
---
.../clang/Basic/DiagnosticSemaKinds.td| 2 +
clang/include/clang/Sema/Sema.h | 3 +
clang/lib/Sema/SemaExpand.cpp | 100 +-
clang/lib/Sema/TreeTransform.h| 81 ++
4 files changed, 162 insertions(+), 24 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 3c3589e0ae22a..d91e1526ae47f 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3700,6 +3700,8 @@ def err_conflicting_codeseg_attribute : Error<
def warn_duplicate_codeseg_attribute : Warning<
"duplicate code segment specifiers">, InGroup;
+def err_expansion_stmt_invalid_init : Error<
+ "cannot expand expression of type %0">;
def err_expansion_stmt_vla : Error<
"cannot expand variable length array type %0">;
def err_expansion_stmt_incomplete : Error<
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index f5a36626a9dad..48bf7ba1083b7 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -15712,6 +15712,9 @@ class Sema final : public SemaBase {
ExprResult BuildCXXExpansionSelectExpr(InitListExpr *Range, Expr *Idx);
+ ExprResult BuildCXXDestructuringExpansionSelectExpr(DecompositionDecl *DD,
+ Expr *Idx);
+
std::optional
ComputeExpansionSize(CXXExpansionStmtPattern *Expansion);
///@}
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index 40891e96e97de..315a4bdfd3a6c 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -220,6 +220,52 @@ TryBuildIterableExpansionStmtInitializer(Sema &S, Expr
*ExpansionInitializer,
return Data;
}
+static StmtResult BuildDestructuringCXXExpansionStmt(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx);
+
+ // The declarations should be attached to the parent decl context.
+ Sema::ContextRAII CtxGuard(
+ S, S.CurContext->getEnclosingNonExpansionStatementContext(),
+ /*NewThis=*/false);
+
+ UnsignedOrNone Arity =
+ S.GetDecompositionElementCount(ExpansionInitializer->getType(),
ColonLoc);
+
+ if (!Arity) {
+S.Diag(ExpansionInitializer->getBeginLoc(),
+ diag::err_expansion_stmt_invalid_init)
+<< ExpansionInitializer->getType()
+<< ExpansionInitializer->getSourceRange();
+return StmtError();
+ }
+
+ QualType AutoRRef = S.Context.getAutoRRefDeductType();
+ SmallVector Bindings;
+ for (unsigned I = 0; I < *Arity; ++I)
+Bindings.push_back(BindingDecl::Create(
+S.Context, S.CurContext, ColonLoc,
+S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)),
+AutoRRef));
+
+ TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef);
+ auto *DD =
+ DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc,
+AutoRRef, TSI, SC_Auto, Bindings);
+
+ if (VarIsConstexpr)
+DD->setConstexpr(true);
+
+ S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD,
LifetimeExtendTemps);
+ S.AddInitializerToDecl(DD, ExpansionInitializer, false);
+ return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc);
+}
+
CXXExpansionStmtDecl *
Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
SourceLocation TemplateKWLoc) {
@@ -368,8 +414,31 @@ StmtResult
Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
Data.EndDecl, LParenLoc, ColonLoc, RParenLoc);
}
- Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
- return StmtError();
+ // If not, try destructuring.
+ StmtResult DecompDeclStmt = BuildDestructuringCXXExpansionStmt(
+ *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(),
+ LifetimeExtendTemps);
+ if (DecompDeclStmt.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ auto *DS = DecompDeclStmt.getAs();
+ auto *DD = cast(DS->getSingleDecl());
+ if (DD->isInvalidDecl())
+return StmtError();
+
+ ExprResult Select = BuildCXXDestructuringExpansionSelectExpr(DD, Index);
+ if (Select.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ if (FinaliseExpansionVar(*this, ExpansionVar, Select))
+return StmtE
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide updated
https://github.com/llvm/llvm-project/pull/169685
>From 13fb7c82109cb09d60cbc7f49fd6b85171f51b9e Mon Sep 17 00:00:00 2001
From: Sirraide
Date: Wed, 26 Nov 2025 17:00:57 +0100
Subject: [PATCH] [Clang] [C++26] Expansion Statements (Part 6)
---
.../clang/Basic/DiagnosticSemaKinds.td| 2 +
clang/include/clang/Sema/Sema.h | 3 +
clang/lib/Sema/SemaExpand.cpp | 101 +-
clang/lib/Sema/TreeTransform.h| 63 +--
4 files changed, 153 insertions(+), 16 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 3c3589e0ae22a..d91e1526ae47f 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3700,6 +3700,8 @@ def err_conflicting_codeseg_attribute : Error<
def warn_duplicate_codeseg_attribute : Warning<
"duplicate code segment specifiers">, InGroup;
+def err_expansion_stmt_invalid_init : Error<
+ "cannot expand expression of type %0">;
def err_expansion_stmt_vla : Error<
"cannot expand variable length array type %0">;
def err_expansion_stmt_incomplete : Error<
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 6685f891be77b..268c81351e744 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -15714,6 +15714,9 @@ class Sema final : public SemaBase {
BuildCXXExpansionInitListSelectExpr(CXXExpansionInitListExpr *Range,
Expr *Idx);
+ ExprResult BuildCXXDestructuringExpansionSelectExpr(DecompositionDecl *DD,
+ Expr *Idx);
+
std::optional
ComputeExpansionSize(CXXExpansionStmtPattern *Expansion);
///@}
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index c4bc38bf1e465..532797c68b534 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -191,6 +191,52 @@ TryBuildIterableExpansionStmtInitializer(Sema &S, Expr
*ExpansionInitializer,
return Data;
}
+static StmtResult BuildDestructuringCXXExpansionStmt(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx);
+
+ // The declarations should be attached to the parent decl context.
+ Sema::ContextRAII CtxGuard(
+ S, S.CurContext->getEnclosingNonExpansionStatementContext(),
+ /*NewThis=*/false);
+
+ UnsignedOrNone Arity =
+ S.GetDecompositionElementCount(ExpansionInitializer->getType(),
ColonLoc);
+
+ if (!Arity) {
+S.Diag(ExpansionInitializer->getBeginLoc(),
+ diag::err_expansion_stmt_invalid_init)
+<< ExpansionInitializer->getType()
+<< ExpansionInitializer->getSourceRange();
+return StmtError();
+ }
+
+ QualType AutoRRef = S.Context.getAutoRRefDeductType();
+ SmallVector Bindings;
+ for (unsigned I = 0; I < *Arity; ++I)
+Bindings.push_back(BindingDecl::Create(
+S.Context, S.CurContext, ColonLoc,
+S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)),
+AutoRRef));
+
+ TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef);
+ auto *DD =
+ DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc,
+AutoRRef, TSI, SC_Auto, Bindings);
+
+ if (VarIsConstexpr)
+DD->setConstexpr(true);
+
+ S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD,
LifetimeExtendTemps);
+ S.AddInitializerToDecl(DD, ExpansionInitializer, false);
+ return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc);
+}
+
CXXExpansionStmtDecl *
Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
SourceLocation TemplateKWLoc) {
@@ -339,8 +385,31 @@ StmtResult
Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
Data.EndDecl, LParenLoc, ColonLoc, RParenLoc);
}
- Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
- return StmtError();
+ // If not, try destructuring.
+ StmtResult DecompDeclStmt = BuildDestructuringCXXExpansionStmt(
+ *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(),
+ LifetimeExtendTemps);
+ if (DecompDeclStmt.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ auto *DS = DecompDeclStmt.getAs();
+ auto *DD = cast(DS->getSingleDecl());
+ if (DD->isInvalidDecl())
+return StmtError();
+
+ ExprResult Select = BuildCXXDestructuringExpansionSelectExpr(DD, Index);
+ if (Select.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ if (FinaliseExpansionVar(*this, E
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide updated
https://github.com/llvm/llvm-project/pull/169685
>From 13fb7c82109cb09d60cbc7f49fd6b85171f51b9e Mon Sep 17 00:00:00 2001
From: Sirraide
Date: Wed, 26 Nov 2025 17:00:57 +0100
Subject: [PATCH] [Clang] [C++26] Expansion Statements (Part 6)
---
.../clang/Basic/DiagnosticSemaKinds.td| 2 +
clang/include/clang/Sema/Sema.h | 3 +
clang/lib/Sema/SemaExpand.cpp | 101 +-
clang/lib/Sema/TreeTransform.h| 63 +--
4 files changed, 153 insertions(+), 16 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 3c3589e0ae22a..d91e1526ae47f 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3700,6 +3700,8 @@ def err_conflicting_codeseg_attribute : Error<
def warn_duplicate_codeseg_attribute : Warning<
"duplicate code segment specifiers">, InGroup;
+def err_expansion_stmt_invalid_init : Error<
+ "cannot expand expression of type %0">;
def err_expansion_stmt_vla : Error<
"cannot expand variable length array type %0">;
def err_expansion_stmt_incomplete : Error<
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 6685f891be77b..268c81351e744 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -15714,6 +15714,9 @@ class Sema final : public SemaBase {
BuildCXXExpansionInitListSelectExpr(CXXExpansionInitListExpr *Range,
Expr *Idx);
+ ExprResult BuildCXXDestructuringExpansionSelectExpr(DecompositionDecl *DD,
+ Expr *Idx);
+
std::optional
ComputeExpansionSize(CXXExpansionStmtPattern *Expansion);
///@}
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index c4bc38bf1e465..532797c68b534 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -191,6 +191,52 @@ TryBuildIterableExpansionStmtInitializer(Sema &S, Expr
*ExpansionInitializer,
return Data;
}
+static StmtResult BuildDestructuringCXXExpansionStmt(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx);
+
+ // The declarations should be attached to the parent decl context.
+ Sema::ContextRAII CtxGuard(
+ S, S.CurContext->getEnclosingNonExpansionStatementContext(),
+ /*NewThis=*/false);
+
+ UnsignedOrNone Arity =
+ S.GetDecompositionElementCount(ExpansionInitializer->getType(),
ColonLoc);
+
+ if (!Arity) {
+S.Diag(ExpansionInitializer->getBeginLoc(),
+ diag::err_expansion_stmt_invalid_init)
+<< ExpansionInitializer->getType()
+<< ExpansionInitializer->getSourceRange();
+return StmtError();
+ }
+
+ QualType AutoRRef = S.Context.getAutoRRefDeductType();
+ SmallVector Bindings;
+ for (unsigned I = 0; I < *Arity; ++I)
+Bindings.push_back(BindingDecl::Create(
+S.Context, S.CurContext, ColonLoc,
+S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)),
+AutoRRef));
+
+ TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef);
+ auto *DD =
+ DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc,
+AutoRRef, TSI, SC_Auto, Bindings);
+
+ if (VarIsConstexpr)
+DD->setConstexpr(true);
+
+ S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD,
LifetimeExtendTemps);
+ S.AddInitializerToDecl(DD, ExpansionInitializer, false);
+ return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc);
+}
+
CXXExpansionStmtDecl *
Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
SourceLocation TemplateKWLoc) {
@@ -339,8 +385,31 @@ StmtResult
Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
Data.EndDecl, LParenLoc, ColonLoc, RParenLoc);
}
- Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
- return StmtError();
+ // If not, try destructuring.
+ StmtResult DecompDeclStmt = BuildDestructuringCXXExpansionStmt(
+ *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(),
+ LifetimeExtendTemps);
+ if (DecompDeclStmt.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ auto *DS = DecompDeclStmt.getAs();
+ auto *DD = cast(DS->getSingleDecl());
+ if (DD->isInvalidDecl())
+return StmtError();
+
+ ExprResult Select = BuildCXXDestructuringExpansionSelectExpr(DD, Index);
+ if (Select.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ if (FinaliseExpansionVar(*this, E
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide updated
https://github.com/llvm/llvm-project/pull/169685
>From b874722179a89969b706fb8f03769abec998ac91 Mon Sep 17 00:00:00 2001
From: Sirraide
Date: Wed, 26 Nov 2025 17:00:57 +0100
Subject: [PATCH] [Clang] [C++26] Expansion Statements (Part 6)
---
.../clang/Basic/DiagnosticSemaKinds.td| 2 +
clang/include/clang/Sema/Sema.h | 3 +
clang/lib/Sema/SemaExpand.cpp | 101 +-
clang/lib/Sema/TreeTransform.h| 63 +--
4 files changed, 153 insertions(+), 16 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 96292d0a4e306..0ddaa461deff5 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3702,6 +3702,8 @@ def err_conflicting_codeseg_attribute : Error<
def warn_duplicate_codeseg_attribute : Warning<
"duplicate code segment specifiers">, InGroup;
+def err_expansion_stmt_invalid_init : Error<
+ "cannot expand expression of type %0">;
def err_expansion_stmt_lambda : Error<
"cannot expand lambda closure type">;
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index f001851b36ff7..b102544342416 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -15703,6 +15703,9 @@ class Sema final : public SemaBase {
BuildCXXExpansionInitListSelectExpr(CXXExpansionInitListExpr *Range,
Expr *Idx);
+ ExprResult BuildCXXDestructuringExpansionSelectExpr(DecompositionDecl *DD,
+ Expr *Idx);
+
std::optional
ComputeExpansionSize(CXXExpansionStmtPattern *Expansion);
///@}
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index 228551c27d2d8..fcc951503deb9 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -173,6 +173,52 @@ TryBuildIterableExpansionStmtInitializer(Sema &S, Expr
*ExpansionInitializer,
return Data;
}
+static StmtResult BuildDestructuringCXXExpansionStmt(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx);
+
+ // The declarations should be attached to the parent decl context.
+ Sema::ContextRAII CtxGuard(
+ S, S.CurContext->getEnclosingNonExpansionStatementContext(),
+ /*NewThis=*/false);
+
+ UnsignedOrNone Arity =
+ S.GetDecompositionElementCount(ExpansionInitializer->getType(),
ColonLoc);
+
+ if (!Arity) {
+S.Diag(ExpansionInitializer->getBeginLoc(),
+ diag::err_expansion_stmt_invalid_init)
+<< ExpansionInitializer->getType()
+<< ExpansionInitializer->getSourceRange();
+return StmtError();
+ }
+
+ QualType AutoRRef = S.Context.getAutoRRefDeductType();
+ SmallVector Bindings;
+ for (unsigned I = 0; I < *Arity; ++I)
+Bindings.push_back(BindingDecl::Create(
+S.Context, S.CurContext, ColonLoc,
+S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)),
+AutoRRef));
+
+ TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef);
+ auto *DD =
+ DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc,
+AutoRRef, TSI, SC_Auto, Bindings);
+
+ if (VarIsConstexpr)
+DD->setConstexpr(true);
+
+ S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD,
LifetimeExtendTemps);
+ S.AddInitializerToDecl(DD, ExpansionInitializer, false);
+ return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc);
+}
+
CXXExpansionStmtDecl *
Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
SourceLocation TemplateKWLoc) {
@@ -309,8 +355,31 @@ StmtResult
Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
Data.EndDecl, LParenLoc, ColonLoc, RParenLoc);
}
- Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
- return StmtError();
+ // If not, try destructuring.
+ StmtResult DecompDeclStmt = BuildDestructuringCXXExpansionStmt(
+ *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(),
+ LifetimeExtendTemps);
+ if (DecompDeclStmt.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ auto *DS = DecompDeclStmt.getAs();
+ auto *DD = cast(DS->getSingleDecl());
+ if (DD->isInvalidDecl())
+return StmtError();
+
+ ExprResult Select = BuildCXXDestructuringExpansionSelectExpr(DD, Index);
+ if (Select.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ if (FinaliseExpansionVar(*this, ExpansionVar, Select))
+return StmtError();
+
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide updated
https://github.com/llvm/llvm-project/pull/169685
>From b874722179a89969b706fb8f03769abec998ac91 Mon Sep 17 00:00:00 2001
From: Sirraide
Date: Wed, 26 Nov 2025 17:00:57 +0100
Subject: [PATCH] [Clang] [C++26] Expansion Statements (Part 6)
---
.../clang/Basic/DiagnosticSemaKinds.td| 2 +
clang/include/clang/Sema/Sema.h | 3 +
clang/lib/Sema/SemaExpand.cpp | 101 +-
clang/lib/Sema/TreeTransform.h| 63 +--
4 files changed, 153 insertions(+), 16 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 96292d0a4e306..0ddaa461deff5 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3702,6 +3702,8 @@ def err_conflicting_codeseg_attribute : Error<
def warn_duplicate_codeseg_attribute : Warning<
"duplicate code segment specifiers">, InGroup;
+def err_expansion_stmt_invalid_init : Error<
+ "cannot expand expression of type %0">;
def err_expansion_stmt_lambda : Error<
"cannot expand lambda closure type">;
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index f001851b36ff7..b102544342416 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -15703,6 +15703,9 @@ class Sema final : public SemaBase {
BuildCXXExpansionInitListSelectExpr(CXXExpansionInitListExpr *Range,
Expr *Idx);
+ ExprResult BuildCXXDestructuringExpansionSelectExpr(DecompositionDecl *DD,
+ Expr *Idx);
+
std::optional
ComputeExpansionSize(CXXExpansionStmtPattern *Expansion);
///@}
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index 228551c27d2d8..fcc951503deb9 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -173,6 +173,52 @@ TryBuildIterableExpansionStmtInitializer(Sema &S, Expr
*ExpansionInitializer,
return Data;
}
+static StmtResult BuildDestructuringCXXExpansionStmt(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx);
+
+ // The declarations should be attached to the parent decl context.
+ Sema::ContextRAII CtxGuard(
+ S, S.CurContext->getEnclosingNonExpansionStatementContext(),
+ /*NewThis=*/false);
+
+ UnsignedOrNone Arity =
+ S.GetDecompositionElementCount(ExpansionInitializer->getType(),
ColonLoc);
+
+ if (!Arity) {
+S.Diag(ExpansionInitializer->getBeginLoc(),
+ diag::err_expansion_stmt_invalid_init)
+<< ExpansionInitializer->getType()
+<< ExpansionInitializer->getSourceRange();
+return StmtError();
+ }
+
+ QualType AutoRRef = S.Context.getAutoRRefDeductType();
+ SmallVector Bindings;
+ for (unsigned I = 0; I < *Arity; ++I)
+Bindings.push_back(BindingDecl::Create(
+S.Context, S.CurContext, ColonLoc,
+S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)),
+AutoRRef));
+
+ TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef);
+ auto *DD =
+ DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc,
+AutoRRef, TSI, SC_Auto, Bindings);
+
+ if (VarIsConstexpr)
+DD->setConstexpr(true);
+
+ S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD,
LifetimeExtendTemps);
+ S.AddInitializerToDecl(DD, ExpansionInitializer, false);
+ return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc);
+}
+
CXXExpansionStmtDecl *
Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
SourceLocation TemplateKWLoc) {
@@ -309,8 +355,31 @@ StmtResult
Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
Data.EndDecl, LParenLoc, ColonLoc, RParenLoc);
}
- Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
- return StmtError();
+ // If not, try destructuring.
+ StmtResult DecompDeclStmt = BuildDestructuringCXXExpansionStmt(
+ *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(),
+ LifetimeExtendTemps);
+ if (DecompDeclStmt.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ auto *DS = DecompDeclStmt.getAs();
+ auto *DD = cast(DS->getSingleDecl());
+ if (DD->isInvalidDecl())
+return StmtError();
+
+ ExprResult Select = BuildCXXDestructuringExpansionSelectExpr(DD, Index);
+ if (Select.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ if (FinaliseExpansionVar(*this, ExpansionVar, Select))
+return StmtError();
+
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide updated
https://github.com/llvm/llvm-project/pull/169685
>From 45151d137b01d1fa9b3a451bb1c5e72ce02d71c7 Mon Sep 17 00:00:00 2001
From: Sirraide
Date: Wed, 26 Nov 2025 17:00:57 +0100
Subject: [PATCH] [Clang] [C++26] Expansion Statements (Part 6)
---
.../clang/Basic/DiagnosticSemaKinds.td| 2 +
clang/include/clang/Sema/Sema.h | 3 +
clang/lib/Sema/SemaExpand.cpp | 101 +-
clang/lib/Sema/TreeTransform.h| 63 +--
4 files changed, 153 insertions(+), 16 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 96292d0a4e306..0ddaa461deff5 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3702,6 +3702,8 @@ def err_conflicting_codeseg_attribute : Error<
def warn_duplicate_codeseg_attribute : Warning<
"duplicate code segment specifiers">, InGroup;
+def err_expansion_stmt_invalid_init : Error<
+ "cannot expand expression of type %0">;
def err_expansion_stmt_lambda : Error<
"cannot expand lambda closure type">;
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index f001851b36ff7..b102544342416 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -15703,6 +15703,9 @@ class Sema final : public SemaBase {
BuildCXXExpansionInitListSelectExpr(CXXExpansionInitListExpr *Range,
Expr *Idx);
+ ExprResult BuildCXXDestructuringExpansionSelectExpr(DecompositionDecl *DD,
+ Expr *Idx);
+
std::optional
ComputeExpansionSize(CXXExpansionStmtPattern *Expansion);
///@}
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index 228551c27d2d8..fcc951503deb9 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -173,6 +173,52 @@ TryBuildIterableExpansionStmtInitializer(Sema &S, Expr
*ExpansionInitializer,
return Data;
}
+static StmtResult BuildDestructuringCXXExpansionStmt(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx);
+
+ // The declarations should be attached to the parent decl context.
+ Sema::ContextRAII CtxGuard(
+ S, S.CurContext->getEnclosingNonExpansionStatementContext(),
+ /*NewThis=*/false);
+
+ UnsignedOrNone Arity =
+ S.GetDecompositionElementCount(ExpansionInitializer->getType(),
ColonLoc);
+
+ if (!Arity) {
+S.Diag(ExpansionInitializer->getBeginLoc(),
+ diag::err_expansion_stmt_invalid_init)
+<< ExpansionInitializer->getType()
+<< ExpansionInitializer->getSourceRange();
+return StmtError();
+ }
+
+ QualType AutoRRef = S.Context.getAutoRRefDeductType();
+ SmallVector Bindings;
+ for (unsigned I = 0; I < *Arity; ++I)
+Bindings.push_back(BindingDecl::Create(
+S.Context, S.CurContext, ColonLoc,
+S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)),
+AutoRRef));
+
+ TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef);
+ auto *DD =
+ DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc,
+AutoRRef, TSI, SC_Auto, Bindings);
+
+ if (VarIsConstexpr)
+DD->setConstexpr(true);
+
+ S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD,
LifetimeExtendTemps);
+ S.AddInitializerToDecl(DD, ExpansionInitializer, false);
+ return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc);
+}
+
CXXExpansionStmtDecl *
Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
SourceLocation TemplateKWLoc) {
@@ -309,8 +355,31 @@ StmtResult
Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
Data.EndDecl, LParenLoc, ColonLoc, RParenLoc);
}
- Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
- return StmtError();
+ // If not, try destructuring.
+ StmtResult DecompDeclStmt = BuildDestructuringCXXExpansionStmt(
+ *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(),
+ LifetimeExtendTemps);
+ if (DecompDeclStmt.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ auto *DS = DecompDeclStmt.getAs();
+ auto *DD = cast(DS->getSingleDecl());
+ if (DD->isInvalidDecl())
+return StmtError();
+
+ ExprResult Select = BuildCXXDestructuringExpansionSelectExpr(DD, Index);
+ if (Select.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ if (FinaliseExpansionVar(*this, ExpansionVar, Select))
+return StmtError();
+
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide updated
https://github.com/llvm/llvm-project/pull/169685
>From 45151d137b01d1fa9b3a451bb1c5e72ce02d71c7 Mon Sep 17 00:00:00 2001
From: Sirraide
Date: Wed, 26 Nov 2025 17:00:57 +0100
Subject: [PATCH] [Clang] [C++26] Expansion Statements (Part 6)
---
.../clang/Basic/DiagnosticSemaKinds.td| 2 +
clang/include/clang/Sema/Sema.h | 3 +
clang/lib/Sema/SemaExpand.cpp | 101 +-
clang/lib/Sema/TreeTransform.h| 63 +--
4 files changed, 153 insertions(+), 16 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 96292d0a4e306..0ddaa461deff5 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3702,6 +3702,8 @@ def err_conflicting_codeseg_attribute : Error<
def warn_duplicate_codeseg_attribute : Warning<
"duplicate code segment specifiers">, InGroup;
+def err_expansion_stmt_invalid_init : Error<
+ "cannot expand expression of type %0">;
def err_expansion_stmt_lambda : Error<
"cannot expand lambda closure type">;
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index f001851b36ff7..b102544342416 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -15703,6 +15703,9 @@ class Sema final : public SemaBase {
BuildCXXExpansionInitListSelectExpr(CXXExpansionInitListExpr *Range,
Expr *Idx);
+ ExprResult BuildCXXDestructuringExpansionSelectExpr(DecompositionDecl *DD,
+ Expr *Idx);
+
std::optional
ComputeExpansionSize(CXXExpansionStmtPattern *Expansion);
///@}
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index 228551c27d2d8..fcc951503deb9 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -173,6 +173,52 @@ TryBuildIterableExpansionStmtInitializer(Sema &S, Expr
*ExpansionInitializer,
return Data;
}
+static StmtResult BuildDestructuringCXXExpansionStmt(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx);
+
+ // The declarations should be attached to the parent decl context.
+ Sema::ContextRAII CtxGuard(
+ S, S.CurContext->getEnclosingNonExpansionStatementContext(),
+ /*NewThis=*/false);
+
+ UnsignedOrNone Arity =
+ S.GetDecompositionElementCount(ExpansionInitializer->getType(),
ColonLoc);
+
+ if (!Arity) {
+S.Diag(ExpansionInitializer->getBeginLoc(),
+ diag::err_expansion_stmt_invalid_init)
+<< ExpansionInitializer->getType()
+<< ExpansionInitializer->getSourceRange();
+return StmtError();
+ }
+
+ QualType AutoRRef = S.Context.getAutoRRefDeductType();
+ SmallVector Bindings;
+ for (unsigned I = 0; I < *Arity; ++I)
+Bindings.push_back(BindingDecl::Create(
+S.Context, S.CurContext, ColonLoc,
+S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)),
+AutoRRef));
+
+ TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef);
+ auto *DD =
+ DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc,
+AutoRRef, TSI, SC_Auto, Bindings);
+
+ if (VarIsConstexpr)
+DD->setConstexpr(true);
+
+ S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD,
LifetimeExtendTemps);
+ S.AddInitializerToDecl(DD, ExpansionInitializer, false);
+ return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc);
+}
+
CXXExpansionStmtDecl *
Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
SourceLocation TemplateKWLoc) {
@@ -309,8 +355,31 @@ StmtResult
Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
Data.EndDecl, LParenLoc, ColonLoc, RParenLoc);
}
- Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
- return StmtError();
+ // If not, try destructuring.
+ StmtResult DecompDeclStmt = BuildDestructuringCXXExpansionStmt(
+ *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(),
+ LifetimeExtendTemps);
+ if (DecompDeclStmt.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ auto *DS = DecompDeclStmt.getAs();
+ auto *DD = cast(DS->getSingleDecl());
+ if (DD->isInvalidDecl())
+return StmtError();
+
+ ExprResult Select = BuildCXXDestructuringExpansionSelectExpr(DD, Index);
+ if (Select.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ if (FinaliseExpansionVar(*this, ExpansionVar, Select))
+return StmtError();
+
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide ready_for_review https://github.com/llvm/llvm-project/pull/169685 ___ llvm-branch-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide edited https://github.com/llvm/llvm-project/pull/169685 ___ llvm-branch-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
llvmbot wrote:
@llvm/pr-subscribers-clang-codegen
Author: None (Sirraide)
Changes
---
Full diff: https://github.com/llvm/llvm-project/pull/169685.diff
4 Files Affected:
- (modified) clang/include/clang/Basic/DiagnosticSemaKinds.td (+2)
- (modified) clang/include/clang/Sema/Sema.h (+3)
- (modified) clang/lib/Sema/SemaExpand.cpp (+96-5)
- (modified) clang/lib/Sema/TreeTransform.h (+52-11)
``diff
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 96292d0a4e306..0ddaa461deff5 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3702,6 +3702,8 @@ def err_conflicting_codeseg_attribute : Error<
def warn_duplicate_codeseg_attribute : Warning<
"duplicate code segment specifiers">, InGroup;
+def err_expansion_stmt_invalid_init : Error<
+ "cannot expand expression of type %0">;
def err_expansion_stmt_lambda : Error<
"cannot expand lambda closure type">;
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index f001851b36ff7..b102544342416 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -15703,6 +15703,9 @@ class Sema final : public SemaBase {
BuildCXXExpansionInitListSelectExpr(CXXExpansionInitListExpr *Range,
Expr *Idx);
+ ExprResult BuildCXXDestructuringExpansionSelectExpr(DecompositionDecl *DD,
+ Expr *Idx);
+
std::optional
ComputeExpansionSize(CXXExpansionStmtPattern *Expansion);
///@}
diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp
index 228551c27d2d8..fcc951503deb9 100644
--- a/clang/lib/Sema/SemaExpand.cpp
+++ b/clang/lib/Sema/SemaExpand.cpp
@@ -173,6 +173,52 @@ TryBuildIterableExpansionStmtInitializer(Sema &S, Expr
*ExpansionInitializer,
return Data;
}
+static StmtResult BuildDestructuringCXXExpansionStmt(
+Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc,
+bool VarIsConstexpr,
+ArrayRef LifetimeExtendTemps) {
+ auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated;
+ if (VarIsConstexpr)
+Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx);
+
+ // The declarations should be attached to the parent decl context.
+ Sema::ContextRAII CtxGuard(
+ S, S.CurContext->getEnclosingNonExpansionStatementContext(),
+ /*NewThis=*/false);
+
+ UnsignedOrNone Arity =
+ S.GetDecompositionElementCount(ExpansionInitializer->getType(),
ColonLoc);
+
+ if (!Arity) {
+S.Diag(ExpansionInitializer->getBeginLoc(),
+ diag::err_expansion_stmt_invalid_init)
+<< ExpansionInitializer->getType()
+<< ExpansionInitializer->getSourceRange();
+return StmtError();
+ }
+
+ QualType AutoRRef = S.Context.getAutoRRefDeductType();
+ SmallVector Bindings;
+ for (unsigned I = 0; I < *Arity; ++I)
+Bindings.push_back(BindingDecl::Create(
+S.Context, S.CurContext, ColonLoc,
+S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)),
+AutoRRef));
+
+ TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef);
+ auto *DD =
+ DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc,
+AutoRRef, TSI, SC_Auto, Bindings);
+
+ if (VarIsConstexpr)
+DD->setConstexpr(true);
+
+ S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD,
LifetimeExtendTemps);
+ S.AddInitializerToDecl(DD, ExpansionInitializer, false);
+ return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc);
+}
+
CXXExpansionStmtDecl *
Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
SourceLocation TemplateKWLoc) {
@@ -309,8 +355,31 @@ StmtResult
Sema::BuildNonEnumeratingCXXExpansionStmtPattern(
Data.EndDecl, LParenLoc, ColonLoc, RParenLoc);
}
- Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
- return StmtError();
+ // If not, try destructuring.
+ StmtResult DecompDeclStmt = BuildDestructuringCXXExpansionStmt(
+ *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(),
+ LifetimeExtendTemps);
+ if (DecompDeclStmt.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ auto *DS = DecompDeclStmt.getAs();
+ auto *DD = cast(DS->getSingleDecl());
+ if (DD->isInvalidDecl())
+return StmtError();
+
+ ExprResult Select = BuildCXXDestructuringExpansionSelectExpr(DD, Index);
+ if (Select.isInvalid()) {
+ActOnInitializerError(ExpansionVar);
+return StmtError();
+ }
+
+ if (FinaliseExpansionVar(*this, ExpansionVar, Select))
+return StmtError();
+
+ return new (Context) CXXDestructuringExpansionStmtPattern(
+ ESD, Init, ExpansionVarStmt, DS, LParenLoc, ColonLoc, RParenLoc);
}
StmtResult Sema::
[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
github-actions[bot] wrote:
# :penguin: Linux x64 Test Results
* 3053 tests passed
* 7 tests skipped
All tests passed but another part of the build **failed**. Click on a failure
below to see the details.
tools/clang/lib/CodeGen/CMakeFiles/obj.clangCodeGen.dir/CGDecl.cpp.o
```
FAILED: tools/clang/lib/CodeGen/CMakeFiles/obj.clangCodeGen.dir/CGDecl.cpp.o
sccache /opt/llvm/bin/clang++ -DCLANG_EXPORTS -DGTEST_HAS_RTTI=0 -D_DEBUG
-D_GLIBCXX_ASSERTIONS -D_GLIBCXX_USE_CXX11_ABI=1 -D_GNU_SOURCE
-D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
-I/home/gha/actions-runner/_work/llvm-project/llvm-project/build/tools/clang/lib/CodeGen
-I/home/gha/actions-runner/_work/llvm-project/llvm-project/clang/lib/CodeGen
-I/home/gha/actions-runner/_work/llvm-project/llvm-project/clang/include
-I/home/gha/actions-runner/_work/llvm-project/llvm-project/build/tools/clang/include
-I/home/gha/actions-runner/_work/llvm-project/llvm-project/build/include
-I/home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/include -gmlt
-fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror
-Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra
-Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers
-pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough
-Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor
-Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion
-Wno-pass-failed -Wmisleading-indentation -Wctad-maybe-unsupported
-fdiagnostics-color -ffunction-sections -fdata-sections -fno-common
-Woverloaded-virtual -Wno-nested-anon-types -O3 -DNDEBUG -std=c++17
-fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -MD -MT
tools/clang/lib/CodeGen/CMakeFiles/obj.clangCodeGen.dir/CGDecl.cpp.o -MF
tools/clang/lib/CodeGen/CMakeFiles/obj.clangCodeGen.dir/CGDecl.cpp.o.d -o
tools/clang/lib/CodeGen/CMakeFiles/obj.clangCodeGen.dir/CGDecl.cpp.o -c
/home/gha/actions-runner/_work/llvm-project/llvm-project/clang/lib/CodeGen/CGDecl.cpp
/home/gha/actions-runner/_work/llvm-project/llvm-project/clang/lib/CodeGen/CGDecl.cpp:53:11:
error: enumeration value 'CXXExpansionStmt' not handled in switch
[-Werror,-Wswitch]
53 | switch (D.getKind()) {
| ^~~
1 error generated.
```
tools/clang/lib/CodeGen/CMakeFiles/obj.clangCodeGen.dir/CGStmt.cpp.o
```
FAILED: tools/clang/lib/CodeGen/CMakeFiles/obj.clangCodeGen.dir/CGStmt.cpp.o
sccache /opt/llvm/bin/clang++ -DCLANG_EXPORTS -DGTEST_HAS_RTTI=0 -D_DEBUG
-D_GLIBCXX_ASSERTIONS -D_GLIBCXX_USE_CXX11_ABI=1 -D_GNU_SOURCE
-D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
-I/home/gha/actions-runner/_work/llvm-project/llvm-project/build/tools/clang/lib/CodeGen
-I/home/gha/actions-runner/_work/llvm-project/llvm-project/clang/lib/CodeGen
-I/home/gha/actions-runner/_work/llvm-project/llvm-project/clang/include
-I/home/gha/actions-runner/_work/llvm-project/llvm-project/build/tools/clang/include
-I/home/gha/actions-runner/_work/llvm-project/llvm-project/build/include
-I/home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/include -gmlt
-fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror
-Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra
-Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers
-pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough
-Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor
-Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion
-Wno-pass-failed -Wmisleading-indentation -Wctad-maybe-unsupported
-fdiagnostics-color -ffunction-sections -fdata-sections -fno-common
-Woverloaded-virtual -Wno-nested-anon-types -O3 -DNDEBUG -std=c++17
-fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -MD -MT
tools/clang/lib/CodeGen/CMakeFiles/obj.clangCodeGen.dir/CGStmt.cpp.o -MF
tools/clang/lib/CodeGen/CMakeFiles/obj.clangCodeGen.dir/CGStmt.cpp.o.d -o
tools/clang/lib/CodeGen/CMakeFiles/obj.clangCodeGen.dir/CGStmt.cpp.o -c
/home/gha/actions-runner/_work/llvm-project/llvm-project/clang/lib/CodeGen/CGStmt.cpp
/home/gha/actions-runner/_work/llvm-project/llvm-project/clang/lib/CodeGen/CGStmt.cpp:100:11:
error: 5 enumeration values not handled in switch:
'CXXIteratingExpansionStmtPatternClass',
'CXXEnumeratingExpansionStmtPatternClass',
'CXXDestructuringExpansionStmtPatternClass'... [-Werror,-Wswitch]
100 | switch (S->getStmtClass()) {
| ^
1 error generated.
```
If these failures are unrelated to your changes (for example tests are broken
or flaky at HEAD), please open an issue at
https://github.com/llvm/llvm-project/issues and add the `infrastructure` label.
https://github.com/llvm/llvm-project/pull/169685
___
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[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 6: Destructuring Expansion Statements) (PR #169685)
https://github.com/Sirraide edited https://github.com/llvm/llvm-project/pull/169685 ___ llvm-branch-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
