Author: Krishna Narayanan Date: 2023-06-14T08:28:35-04:00 New Revision: 20e81a80e9cb6403f850ab981438f3d9d88b5a4b
URL: https://github.com/llvm/llvm-project/commit/20e81a80e9cb6403f850ab981438f3d9d88b5a4b DIFF: https://github.com/llvm/llvm-project/commit/20e81a80e9cb6403f850ab981438f3d9d88b5a4b.diff LOG: Update with warning message for comparison to NULL pointer The tautological comparison warning was not properly looking through parenthesized expressions, which is now fixed. Fixes https://github.com/llvm/llvm-project/issues/42992 Differential Revision: https://reviews.llvm.org/D149000 Added: Modified: clang/docs/ReleaseNotes.rst clang/lib/Sema/SemaChecking.cpp clang/test/Sema/conditional-expr.c clang/test/Sema/warn-tautological-compare.c Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 6bfd77cc91028..2960183eb8c5f 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -340,6 +340,8 @@ Improvements to Clang's diagnostics can be controlled using ``-fcaret-diagnostics-max-lines=``. - Clang no longer emits ``-Wunused-variable`` warnings for variables declared with ``__attribute__((cleanup(...)))`` to match GCC's behavior. +- Clang now issues expected warnings for situations of comparing with NULL pointers. + (`#42992: <https://github.com/llvm/llvm-project/issues/42992>`_) Bug Fixes in This Version ------------------------- diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp index 96f8d49b80f2c..55220138f94f5 100644 --- a/clang/lib/Sema/SemaChecking.cpp +++ b/clang/lib/Sema/SemaChecking.cpp @@ -14844,7 +14844,7 @@ void Sema::DiagnoseAlwaysNonNullPointer(Expr *E, bool IsAddressOf = false; - if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { + if (auto *UO = dyn_cast<UnaryOperator>(E->IgnoreParens())) { if (UO->getOpcode() != UO_AddrOf) return; IsAddressOf = true; diff --git a/clang/test/Sema/conditional-expr.c b/clang/test/Sema/conditional-expr.c index 81997459c1f20..b54b689ec4f05 100644 --- a/clang/test/Sema/conditional-expr.c +++ b/clang/test/Sema/conditional-expr.c @@ -86,7 +86,8 @@ void foo(void) { int Postgresql(void) { char x; - return ((((&x) != ((void *) 0)) ? (*(&x) = ((char) 1)) : (void) ((void *) 0)), (unsigned long) ((void *) 0)); // expected-warning {{C99 forbids conditional expressions with only one void side}} + return ((((&x) != ((void *) 0)) ? (*(&x) = ((char) 1)) : (void) ((void *) 0)), (unsigned long) ((void *) 0)); /* expected-warning {{C99 forbids conditional expressions with only one void side}} + expected-warning {{comparison of address of 'x' not equal to a null pointer is always true}} */ } #define nil ((void*) 0) diff --git a/clang/test/Sema/warn-tautological-compare.c b/clang/test/Sema/warn-tautological-compare.c index 88e0f98b48ea4..dd41f04036391 100644 --- a/clang/test/Sema/warn-tautological-compare.c +++ b/clang/test/Sema/warn-tautological-compare.c @@ -93,3 +93,8 @@ void test_conditional_operator(void) { x = array ? 1 : 0; // expected-warning {{address of array}} x = &x ? 1 : 0; // expected-warning {{address of 'x'}} } + +void test4(void) { + int *a = (void *) 0; + int b = (&a) == ((void *) 0); // expected-warning {{comparison of address of 'a' equal to a null pointer is always false}} +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
