Author: Oleksandr T. Date: 2026-01-12T15:50:05+02:00 New Revision: 8380b57b7ec4adc715c7e4458dedb07e586b9477
URL: https://github.com/llvm/llvm-project/commit/8380b57b7ec4adc715c7e4458dedb07e586b9477 DIFF: https://github.com/llvm/llvm-project/commit/8380b57b7ec4adc715c7e4458dedb07e586b9477.diff LOG: [Clang] prevent an assertion failure caused by C++ constant expression checks in C23 floating conversions (#174113) Fixes #173847 --- This patch addresses an assertion failure during compilation of C23 code involving floating-point conversions. As part of the C23 constexpr support introduced in PR #73099, Clang began reusing parts of the C++ constant evaluation and narrowing logic. In C23 mode, a failed constant evaluation caused the condition to proceed to C++ constant-expression checks, resulting in an assertion failure. This change evaluates constants using `EvaluateAsRValue` in C23 mode and restricts C++ constant-expression checks to C++ mode. Added: Modified: clang/docs/ReleaseNotes.rst clang/lib/Sema/SemaOverload.cpp clang/test/Sema/constexpr.c Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 165e7f186acf3..c56d2015f7a3f 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -654,6 +654,7 @@ Bug Fixes to C++ Support - Fixed a crash when parsing the ``enable_if`` attribute on C function declarations with identifier-list parameters. (#GH173826) - Fixed an assertion failure triggered by nested lambdas during capture handling. (#GH172814) - Fixed an assertion failure in vector conversions involving instantiation-dependent template expressions. (#GH173347) +- Fixed an assertion failure in floating conversion narrowing caused by C++ constant expression checks in C23 mode. (#GH173847) Bug Fixes to AST Handling ^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp index a7a3b7900ccc2..7115b8b7d446a 100644 --- a/clang/lib/Sema/SemaOverload.cpp +++ b/clang/lib/Sema/SemaOverload.cpp @@ -449,7 +449,8 @@ NarrowingKind StandardConversionSequence::getNarrowingKind( Expr::EvalResult R; if ((Ctx.getLangOpts().C23 && Initializer->EvaluateAsRValue(R, Ctx)) || - Initializer->isCXX11ConstantExpr(Ctx, &ConstantValue)) { + ((Ctx.getLangOpts().CPlusPlus && + Initializer->isCXX11ConstantExpr(Ctx, &ConstantValue)))) { // Constant! if (Ctx.getLangOpts().C23) ConstantValue = R.Val; diff --git a/clang/test/Sema/constexpr.c b/clang/test/Sema/constexpr.c index e9b738ab4d190..16255c264423a 100644 --- a/clang/test/Sema/constexpr.c +++ b/clang/test/Sema/constexpr.c @@ -401,3 +401,11 @@ bool issue155507(v2int16_t a, v2int16_t b) { constexpr bool b2 = (bool)nullptr; _Static_assert(!b2); + +double ghissue173847(double a) { + double result = 3.0 / (a + 4.5 - 2.1 * 0.7); + return result; +} +void ghissue173847_test() { + constexpr float f_const = ghissue173847(2.0); // expected-error {{constexpr variable 'f_const' must be initialized by a constant expression}} +} _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
