[PATCH] D150036: [Clang] Correctly handle allocation in template arguments

[Corentin Jabot via Phabricator via cfe-commits]

cor3ntin updated this revision to Diff 520154.
cor3ntin added a comment.

Update commit message and add comment referencing the standard.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D150036/new/

https://reviews.llvm.org/D150036

Files:
  clang/docs/ReleaseNotes.rst
  clang/lib/AST/ExprConstant.cpp
  clang/test/SemaCXX/cxx2a-constexpr-dynalloc.cpp


Index: clang/test/SemaCXX/cxx2a-constexpr-dynalloc.cpp
===================================================================
--- clang/test/SemaCXX/cxx2a-constexpr-dynalloc.cpp
+++ clang/test/SemaCXX/cxx2a-constexpr-dynalloc.cpp
@@ -215,3 +215,27 @@
   }
   static_assert(h());
 }
+
+namespace GH62462 {
+
+class string {
+public:
+  char *mem;
+  constexpr string() {
+    this->mem = new char(1);
+  }
+  constexpr ~string() {
+    delete this->mem;
+  }
+  constexpr unsigned size() const { return 4; }
+};
+
+
+template <unsigned N>
+void test() {};
+
+void f() {
+    test<string().size()>();
+}
+
+}
Index: clang/lib/AST/ExprConstant.cpp
===================================================================
--- clang/lib/AST/ExprConstant.cpp
+++ clang/lib/AST/ExprConstant.cpp
@@ -15354,8 +15354,15 @@
   LValue LVal;
   LVal.set(Base);
 
-  if (!::EvaluateInPlace(Result.Val, Info, LVal, this) || 
Result.HasSideEffects)
-    return false;
+  {
+    // C++23 [intro.execution]/p5
+    // A full-expression is [...] a constant-expression
+    // So we need to make sure temporary objects are destroyed after having 
evaluating
+    // the expression (per C++23 [class.temporary]/p4).
+    FullExpressionRAII Scope(Info);
+    if (!::EvaluateInPlace(Result.Val, Info, LVal, this) || 
Result.HasSideEffects  || !Scope.destroy())
+      return false;
+  }
 
   if (!Info.discardCleanups())
     llvm_unreachable("Unhandled cleanup; missing full expression marker?");
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -381,6 +381,8 @@
 - Fix overly aggressive lifetime checks for parenthesized aggregate
   initialization.
   (`#61567 <https://github.com/llvm/llvm-project/issues/61567>`_)
+- Fix handling of constexpr dynamic memory allocations in template
+  arguments. (`#62462 <https://github.com/llvm/llvm-project/issues/62462>`)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^



Index: clang/test/SemaCXX/cxx2a-constexpr-dynalloc.cpp
===================================================================
--- clang/test/SemaCXX/cxx2a-constexpr-dynalloc.cpp
+++ clang/test/SemaCXX/cxx2a-constexpr-dynalloc.cpp
@@ -215,3 +215,27 @@
   }
   static_assert(h());
 }
+
+namespace GH62462 {
+
+class string {
+public:
+  char *mem;
+  constexpr string() {
+    this->mem = new char(1);
+  }
+  constexpr ~string() {
+    delete this->mem;
+  }
+  constexpr unsigned size() const { return 4; }
+};
+
+
+template <unsigned N>
+void test() {};
+
+void f() {
+    test<string().size()>();
+}
+
+}
Index: clang/lib/AST/ExprConstant.cpp
===================================================================
--- clang/lib/AST/ExprConstant.cpp
+++ clang/lib/AST/ExprConstant.cpp
@@ -15354,8 +15354,15 @@
   LValue LVal;
   LVal.set(Base);
 
-  if (!::EvaluateInPlace(Result.Val, Info, LVal, this) || Result.HasSideEffects)
-    return false;
+  {
+    // C++23 [intro.execution]/p5
+    // A full-expression is [...] a constant-expression
+    // So we need to make sure temporary objects are destroyed after having evaluating
+    // the expression (per C++23 [class.temporary]/p4).
+    FullExpressionRAII Scope(Info);
+    if (!::EvaluateInPlace(Result.Val, Info, LVal, this) || Result.HasSideEffects  || !Scope.destroy())
+      return false;
+  }
 
   if (!Info.discardCleanups())
     llvm_unreachable("Unhandled cleanup; missing full expression marker?");
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -381,6 +381,8 @@
 - Fix overly aggressive lifetime checks for parenthesized aggregate
   initialization.
   (`#61567 <https://github.com/llvm/llvm-project/issues/61567>`_)
+- Fix handling of constexpr dynamic memory allocations in template
+  arguments. (`#62462 <https://github.com/llvm/llvm-project/issues/62462>`)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

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