Author: Oleksandr T. Date: 2024-08-18T12:45:20+02:00 New Revision: c4092d326ae4989f54c5f01d3a077841fd76bc2f
URL: https://github.com/llvm/llvm-project/commit/c4092d326ae4989f54c5f01d3a077841fd76bc2f DIFF: https://github.com/llvm/llvm-project/commit/c4092d326ae4989f54c5f01d3a077841fd76bc2f.diff LOG: [Clang] warn on discarded [[nodiscard]] function results after casting in C (#104677) Fixes #104391 Added: Modified: clang/docs/ReleaseNotes.rst clang/lib/Sema/SemaStmt.cpp clang/test/Sema/c2x-nodiscard.c Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 12a3707db8a39f..11301e4c7dc4a2 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -218,6 +218,8 @@ Improvements to Clang's diagnostics - Clang now diagnoses the use of ``main`` in an ``extern`` context as invalid according to [basic.start.main] p3. Fixes #GH101512. +- Clang now diagnoses when the result of a [[nodiscard]] function is discarded after being cast in C. Fixes #GH104391. + Improvements to Clang's time-trace ---------------------------------- diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp index d283eaa511011b..ba681671eb3290 100644 --- a/clang/lib/Sema/SemaStmt.cpp +++ b/clang/lib/Sema/SemaStmt.cpp @@ -281,7 +281,8 @@ void Sema::DiagnoseUnusedExprResult(const Stmt *S, unsigned DiagID) { E = WarnExpr; if (const auto *Cast = dyn_cast<CastExpr>(E)) if (Cast->getCastKind() == CK_NoOp || - Cast->getCastKind() == CK_ConstructorConversion) + Cast->getCastKind() == CK_ConstructorConversion || + Cast->getCastKind() == CK_IntegralCast) E = Cast->getSubExpr()->IgnoreImpCasts(); if (const CallExpr *CE = dyn_cast<CallExpr>(E)) { diff --git a/clang/test/Sema/c2x-nodiscard.c b/clang/test/Sema/c2x-nodiscard.c index cb33c0c242e7db..f8b0567366465d 100644 --- a/clang/test/Sema/c2x-nodiscard.c +++ b/clang/test/Sema/c2x-nodiscard.c @@ -54,3 +54,9 @@ void test_missiles(void) { launch_missiles(); } +[[nodiscard]] int f3(); + +void GH104391() { +#define M (unsigned int) f3() + M; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
