https://github.com/katzdm created https://github.com/llvm/llvm-project/pull/89702
The following program is [accepted](https://godbolt.org/z/oEc34Trh4) by Clang, EDG, and MSVC, but rejected by Clang: ```cpp #include <vector> consteval auto fn() { return std::vector {1,2,3}; } template <typename T = int> void fn2() { (void)[]() consteval { for (auto e : fn()) {} }; } void caller() { fn2(); } ``` The stated diagnostic is: ```cpp <source>:8:21: error: call to consteval function 'fn' is not a constant expression 8 | for (auto e : fn()) {} ``` The body of the lambda should be evaluated as within an immediate function context when the lambda is marked as `consteval`. >From 1db83800ef13fae454709c8ba4a7b80728c7bcbe Mon Sep 17 00:00:00 2001 From: Dan Katz <kat...@gmail.com> Date: Mon, 22 Apr 2024 22:39:06 -0400 Subject: [PATCH] Push immediate function context while transforming lambdas in templates. --- clang/docs/ReleaseNotes.rst | 3 +++ clang/lib/Sema/TreeTransform.h | 2 ++ clang/test/SemaCXX/cxx2a-consteval.cpp | 20 ++++++++++++++++++++ 3 files changed, 25 insertions(+) diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 45a9a79739a4eb..0efdcac3c4b8e1 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -420,6 +420,9 @@ Bug Fixes in This Version - Fixed a regression in CTAD that a friend declaration that befriends itself may cause incorrect constraint substitution. (#GH86769). +- Fixed bug in which the body of a consteval lambda within a template was not parsed as within an + immediate function context. + Bug Fixes to Compiler Builtins ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h index 284c9173e68ed5..a3ddebb3ca5963 100644 --- a/clang/lib/Sema/TreeTransform.h +++ b/clang/lib/Sema/TreeTransform.h @@ -14044,6 +14044,8 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { // FIXME: Sema's lambda-building mechanism expects us to push an expression // evaluation context even if we're not transforming the function body. getSema().PushExpressionEvaluationContext( + E->getCallOperator()->isConsteval() ? + Sema::ExpressionEvaluationContext::ImmediateFunctionContext : Sema::ExpressionEvaluationContext::PotentiallyEvaluated); Sema::CodeSynthesisContext C; diff --git a/clang/test/SemaCXX/cxx2a-consteval.cpp b/clang/test/SemaCXX/cxx2a-consteval.cpp index 192621225a543c..b19e25e26c214c 100644 --- a/clang/test/SemaCXX/cxx2a-consteval.cpp +++ b/clang/test/SemaCXX/cxx2a-consteval.cpp @@ -260,6 +260,26 @@ int(*test)(int) = l1; } +namespace consteval_dependent_lambda { +struct S { + int *value; + constexpr S(int v) : value(new int {v}) {} + constexpr ~S() { delete value; } +}; +consteval S fn() { return S(5); } + +template <typename T> +void fn2() { + (void)[]() consteval -> int { + return *(fn().value); // OK, immediate context + }; +} + +void caller() { + fn2<int>(); +} +} + namespace std { template <typename T> struct remove_reference { using type = T; }; _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
