Rakete1111 updated this revision to Diff 154880.
Rakete1111 added a comment.
Rebased + friendly ping
https://reviews.llvm.org/D37442
Files:
include/clang/Basic/DiagnosticSemaKinds.td
include/clang/Sema/Sema.h
lib/Parse/ParseDecl.cpp
lib/Parse/ParseDeclCXX.cpp
lib/Parse/ParseStmt.cpp
lib/Parse/ParseTemplate.cpp
lib/Sema/Sema.cpp
lib/Sema/SemaExpr.cpp
lib/Sema/SemaExprCXX.cpp
lib/Sema/TreeTransform.h
test/CXX/expr/expr.prim/expr.prim.lambda/p2-template-parameter.cpp
Index: test/CXX/expr/expr.prim/expr.prim.lambda/p2-template-parameter.cpp
===================================================================
--- test/CXX/expr/expr.prim/expr.prim.lambda/p2-template-parameter.cpp
+++ test/CXX/expr/expr.prim/expr.prim.lambda/p2-template-parameter.cpp
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -std=c++17 %s -verify
+
+template<auto> struct Nothing {};
+
+void pr33696() {
+ Nothing<[]() { return 0; }()> nothing; // expected-error{{a lambda expression cannot appear in this context}}
+}
Index: lib/Sema/TreeTransform.h
===================================================================
--- lib/Sema/TreeTransform.h
+++ lib/Sema/TreeTransform.h
@@ -3859,6 +3859,10 @@
bool TreeTransform<Derived>::TransformTemplateArgument(
const TemplateArgumentLoc &Input,
TemplateArgumentLoc &Output, bool Uneval) {
+ EnterExpressionEvaluationContext EEEC(
+ SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated,
+ /*LambdaContextDecl=*/nullptr, /*ExprContext=*/
+ Sema::ExpressionEvaluationContextRecord::EK_TemplateArgument);
const TemplateArgument &Arg = Input.getArgument();
switch (Arg.getKind()) {
case TemplateArgument::Null:
@@ -5494,7 +5498,7 @@
// decltype expressions are not potentially evaluated contexts
EnterExpressionEvaluationContext Unevaluated(
SemaRef, Sema::ExpressionEvaluationContext::Unevaluated, nullptr,
- /*IsDecltype=*/true);
+ Sema::ExpressionEvaluationContextRecord::EK_Decltype);
ExprResult E = getDerived().TransformExpr(T->getUnderlyingExpr());
if (E.isInvalid())
Index: lib/Sema/SemaExprCXX.cpp
===================================================================
--- lib/Sema/SemaExprCXX.cpp
+++ lib/Sema/SemaExprCXX.cpp
@@ -6434,7 +6434,8 @@
if (RD->isInvalidDecl() || RD->isDependentContext())
return E;
- bool IsDecltype = ExprEvalContexts.back().IsDecltype;
+ bool IsDecltype = ExprEvalContexts.back().ExprContext ==
+ ExpressionEvaluationContextRecord::EK_Decltype;
CXXDestructorDecl *Destructor = IsDecltype ? nullptr : LookupDestructor(RD);
if (Destructor) {
@@ -6516,7 +6517,9 @@
/// are omitted for the 'topmost' call in the decltype expression. If the
/// topmost call bound a temporary, strip that temporary off the expression.
ExprResult Sema::ActOnDecltypeExpression(Expr *E) {
- assert(ExprEvalContexts.back().IsDecltype && "not in a decltype expression");
+ assert(ExprEvalContexts.back().ExprContext ==
+ ExpressionEvaluationContextRecord::EK_Decltype &&
+ "not in a decltype expression");
// C++11 [expr.call]p11:
// If a function call is a prvalue of object type,
@@ -6558,7 +6561,8 @@
TopBind = nullptr;
// Disable the special decltype handling now.
- ExprEvalContexts.back().IsDecltype = false;
+ ExprEvalContexts.back().ExprContext =
+ ExpressionEvaluationContextRecord::EK_Other;
// In MS mode, don't perform any extra checking of call return types within a
// decltype expression.
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -14132,53 +14132,53 @@
}
void
-Sema::PushExpressionEvaluationContext(ExpressionEvaluationContext NewContext,
- Decl *LambdaContextDecl,
- bool IsDecltype) {
+Sema::PushExpressionEvaluationContext(
+ ExpressionEvaluationContext NewContext, Decl *LambdaContextDecl,
+ ExpressionEvaluationContextRecord::ExpressionKind ExprContext) {
ExprEvalContexts.emplace_back(NewContext, ExprCleanupObjects.size(), Cleanup,
- LambdaContextDecl, IsDecltype);
+ LambdaContextDecl, ExprContext);
Cleanup.reset();
if (!MaybeODRUseExprs.empty())
std::swap(MaybeODRUseExprs, ExprEvalContexts.back().SavedMaybeODRUseExprs);
}
void
-Sema::PushExpressionEvaluationContext(ExpressionEvaluationContext NewContext,
- ReuseLambdaContextDecl_t,
- bool IsDecltype) {
+Sema::PushExpressionEvaluationContext(
+ ExpressionEvaluationContext NewContext, ReuseLambdaContextDecl_t,
+ ExpressionEvaluationContextRecord::ExpressionKind ExprContext) {
Decl *ClosureContextDecl = ExprEvalContexts.back().ManglingContextDecl;
- PushExpressionEvaluationContext(NewContext, ClosureContextDecl, IsDecltype);
+ PushExpressionEvaluationContext(NewContext, ClosureContextDecl, ExprContext);
}
void Sema::PopExpressionEvaluationContext() {
ExpressionEvaluationContextRecord& Rec = ExprEvalContexts.back();
unsigned NumTypos = Rec.NumTypos;
if (!Rec.Lambdas.empty()) {
- if (Rec.isUnevaluated() || Rec.isConstantEvaluated()) {
+ using ExpressionKind = ExpressionEvaluationContextRecord::ExpressionKind;
+ if (Rec.ExprContext == ExpressionKind::EK_TemplateArgument || Rec.isUnevaluated() ||
+ (Rec.isConstantEvaluated() && !getLangOpts().CPlusPlus17)) {
unsigned D;
if (Rec.isUnevaluated()) {
// C++11 [expr.prim.lambda]p2:
// A lambda-expression shall not appear in an unevaluated operand
// (Clause 5).
D = diag::err_lambda_unevaluated_operand;
- } else {
+ } else if (Rec.isConstantEvaluated() && !getLangOpts().CPlusPlus17) {
// C++1y [expr.const]p2:
// A conditional-expression e is a core constant expression unless the
// evaluation of e, following the rules of the abstract machine, would
// evaluate [...] a lambda-expression.
D = diag::err_lambda_in_constant_expression;
- }
+ } else if (Rec.ExprContext == ExpressionKind::EK_TemplateArgument) {
+ // C++17 [expr.prim.lamda]p2:
+ // A lambda-expression shall not appear [...] in a template-argument.
+ D = diag::err_lambda_in_invalid_context;
+ } else
+ llvm_unreachable("Couldn't infer lambda error message.");
- // C++1z allows lambda expressions as core constant expressions.
- // FIXME: In C++1z, reinstate the restrictions on lambda expressions (CWG
- // 1607) from appearing within template-arguments and array-bounds that
- // are part of function-signatures. Be mindful that P0315 (Lambdas in
- // unevaluated contexts) might lift some of these restrictions in a
- // future version.
- if (!Rec.isConstantEvaluated() || !getLangOpts().CPlusPlus17)
- for (const auto *L : Rec.Lambdas)
- Diag(L->getLocStart(), D);
+ for (const auto *L : Rec.Lambdas)
+ Diag(L->getLocStart(), D);
} else {
// Mark the capture expressions odr-used. This was deferred
// during lambda expression creation.
@@ -15637,7 +15637,8 @@
// If we're inside a decltype's expression, don't check for a valid return
// type or construct temporaries until we know whether this is the last call.
- if (ExprEvalContexts.back().IsDecltype) {
+ if (ExprEvalContexts.back().ExprContext ==
+ ExpressionEvaluationContextRecord::EK_Decltype) {
ExprEvalContexts.back().DelayedDecltypeCalls.push_back(CE);
return false;
}
Index: lib/Sema/Sema.cpp
===================================================================
--- lib/Sema/Sema.cpp
+++ lib/Sema/Sema.cpp
@@ -163,7 +163,7 @@
ExprEvalContexts.emplace_back(
ExpressionEvaluationContext::PotentiallyEvaluated, 0, CleanupInfo{},
- nullptr, false);
+ nullptr, ExpressionEvaluationContextRecord::EK_Other);
PreallocatedFunctionScope.reset(new FunctionScopeInfo(Diags));
Index: lib/Parse/ParseTemplate.cpp
===================================================================
--- lib/Parse/ParseTemplate.cpp
+++ lib/Parse/ParseTemplate.cpp
@@ -1235,7 +1235,9 @@
// argument before trying to disambiguate.
EnterExpressionEvaluationContext EnterConstantEvaluated(
- Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);
+ Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated,
+ /*LambdaContextDecl=*/nullptr,
+ /*ExprContext=*/Sema::ExpressionEvaluationContextRecord::EK_TemplateArgument);
if (isCXXTypeId(TypeIdAsTemplateArgument)) {
TypeResult TypeArg = ParseTypeName(
/*Range=*/nullptr, DeclaratorContext::TemplateArgContext);
Index: lib/Parse/ParseStmt.cpp
===================================================================
--- lib/Parse/ParseStmt.cpp
+++ lib/Parse/ParseStmt.cpp
@@ -1196,7 +1196,7 @@
{
EnterExpressionEvaluationContext PotentiallyDiscarded(
Actions, Sema::ExpressionEvaluationContext::DiscardedStatement, nullptr,
- false,
+ Sema::ExpressionEvaluationContextRecord::EK_Other,
/*ShouldEnter=*/ConstexprCondition && !*ConstexprCondition);
ThenStmt = ParseStatement(&InnerStatementTrailingElseLoc);
}
@@ -1230,7 +1230,7 @@
EnterExpressionEvaluationContext PotentiallyDiscarded(
Actions, Sema::ExpressionEvaluationContext::DiscardedStatement, nullptr,
- false,
+ Sema::ExpressionEvaluationContextRecord::EK_Other,
/*ShouldEnter=*/ConstexprCondition && *ConstexprCondition);
ElseStmt = ParseStatement();
Index: lib/Parse/ParseDeclCXX.cpp
===================================================================
--- lib/Parse/ParseDeclCXX.cpp
+++ lib/Parse/ParseDeclCXX.cpp
@@ -942,7 +942,7 @@
// The operand of the decltype specifier is an unevaluated operand.
EnterExpressionEvaluationContext Unevaluated(
Actions, Sema::ExpressionEvaluationContext::Unevaluated, nullptr,
- /*IsDecltype=*/true);
+ Sema::ExpressionEvaluationContextRecord::EK_Decltype);
Result =
Actions.CorrectDelayedTyposInExpr(ParseExpression(), [](Expr *E) {
return E->hasPlaceholderType() ? ExprError() : E;
Index: lib/Parse/ParseDecl.cpp
===================================================================
--- lib/Parse/ParseDecl.cpp
+++ lib/Parse/ParseDecl.cpp
@@ -309,9 +309,7 @@
EnterExpressionEvaluationContext Unevaluated(
Actions,
Uneval ? Sema::ExpressionEvaluationContext::Unevaluated
- : Sema::ExpressionEvaluationContext::ConstantEvaluated,
- /*LambdaContextDecl=*/nullptr,
- /*IsDecltype=*/false);
+ : Sema::ExpressionEvaluationContext::ConstantEvaluated);
ExprResult ArgExpr(
Actions.CorrectDelayedTyposInExpr(ParseAssignmentExpression()));
Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -979,15 +979,21 @@
/// expressions for which we have deferred checking the destructor.
SmallVector<CXXBindTemporaryExpr *, 8> DelayedDecltypeBinds;
+ /// \brief Describes whether we are in an expression constext which we have
+ /// to handle differently.
+ enum ExpressionKind {
+ EK_Decltype, EK_TemplateArgument, EK_Other
+ } ExprContext;
+
ExpressionEvaluationContextRecord(ExpressionEvaluationContext Context,
unsigned NumCleanupObjects,
CleanupInfo ParentCleanup,
Decl *ManglingContextDecl,
- bool IsDecltype)
- : Context(Context), ParentCleanup(ParentCleanup),
- IsDecltype(IsDecltype), NumCleanupObjects(NumCleanupObjects),
- NumTypos(0),
- ManglingContextDecl(ManglingContextDecl), MangleNumbering() { }
+ ExpressionKind ExprContext)
+ : Context(Context), ParentCleanup(ParentCleanup),
+ NumCleanupObjects(NumCleanupObjects), NumTypos(0),
+ ManglingContextDecl(ManglingContextDecl), MangleNumbering(),
+ ExprContext(ExprContext) {}
/// Retrieve the mangling numbering context, used to consistently
/// number constructs like lambdas for mangling.
@@ -3989,13 +3995,13 @@
void DiagnoseSentinelCalls(NamedDecl *D, SourceLocation Loc,
ArrayRef<Expr *> Args);
- void PushExpressionEvaluationContext(ExpressionEvaluationContext NewContext,
- Decl *LambdaContextDecl = nullptr,
- bool IsDecltype = false);
+ void PushExpressionEvaluationContext(
+ ExpressionEvaluationContext NewContext, Decl *LambdaContextDecl = nullptr,
+ ExpressionEvaluationContextRecord::ExpressionKind Type = ExpressionEvaluationContextRecord::EK_Other);
enum ReuseLambdaContextDecl_t { ReuseLambdaContextDecl };
- void PushExpressionEvaluationContext(ExpressionEvaluationContext NewContext,
- ReuseLambdaContextDecl_t,
- bool IsDecltype = false);
+ void PushExpressionEvaluationContext(
+ ExpressionEvaluationContext NewContext, ReuseLambdaContextDecl_t,
+ ExpressionEvaluationContextRecord::ExpressionKind Type = ExpressionEvaluationContextRecord::EK_Other);
void PopExpressionEvaluationContext();
void DiscardCleanupsInEvaluationContext();
@@ -10748,25 +10754,25 @@
bool Entered = true;
public:
-
- EnterExpressionEvaluationContext(Sema &Actions,
- Sema::ExpressionEvaluationContext NewContext,
- Decl *LambdaContextDecl = nullptr,
- bool IsDecltype = false,
- bool ShouldEnter = true)
+ EnterExpressionEvaluationContext(
+ Sema &Actions, Sema::ExpressionEvaluationContext NewContext,
+ Decl *LambdaContextDecl = nullptr,
+ Sema::ExpressionEvaluationContextRecord::ExpressionKind ExprContext =
+ Sema::ExpressionEvaluationContextRecord::EK_Other,
+ bool ShouldEnter = true)
: Actions(Actions), Entered(ShouldEnter) {
if (Entered)
Actions.PushExpressionEvaluationContext(NewContext, LambdaContextDecl,
- IsDecltype);
+ ExprContext);
}
- EnterExpressionEvaluationContext(Sema &Actions,
- Sema::ExpressionEvaluationContext NewContext,
- Sema::ReuseLambdaContextDecl_t,
- bool IsDecltype = false)
- : Actions(Actions) {
- Actions.PushExpressionEvaluationContext(NewContext,
- Sema::ReuseLambdaContextDecl,
- IsDecltype);
+ EnterExpressionEvaluationContext(
+ Sema &Actions, Sema::ExpressionEvaluationContext NewContext,
+ Sema::ReuseLambdaContextDecl_t,
+ Sema::ExpressionEvaluationContextRecord::ExpressionKind ExprContext =
+ Sema::ExpressionEvaluationContextRecord::EK_Other)
+ : Actions(Actions) {
+ Actions.PushExpressionEvaluationContext(
+ NewContext, Sema::ReuseLambdaContextDecl, ExprContext);
}
enum InitListTag { InitList };
@@ -10780,7 +10786,7 @@
if (ShouldEnter && Actions.isUnevaluatedContext() &&
Actions.getLangOpts().CPlusPlus11) {
Actions.PushExpressionEvaluationContext(
- Sema::ExpressionEvaluationContext::UnevaluatedList, nullptr, false);
+ Sema::ExpressionEvaluationContext::UnevaluatedList);
Entered = true;
}
}
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -6487,6 +6487,8 @@
"lambda expression in an unevaluated operand">;
def err_lambda_in_constant_expression : Error<
"a lambda expression may not appear inside of a constant expression">;
+ def err_lambda_in_invalid_context : Error<
+ "a lambda expression cannot appear in this context">;
def err_lambda_return_init_list : Error<
"cannot deduce lambda return type from initializer list">;
def err_lambda_capture_default_arg : Error<
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