llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang Author: Donát Nagy (NagyDonat) <details> <summary>Changes</summary> Add a FIXME testcase which documents less than ideal behavior of the analyzer when a `const char *` is converted to `const unsigned char *`. This testcase is motivated by an ArrayBoundV2 report produced on the source file `id3v2enc.c` within the ffmpeg project. --- Full diff: https://github.com/llvm/llvm-project/pull/108799.diff 1 Files Affected: - (modified) clang/test/Analysis/out-of-bounds.c (+17-1) ``````````diff diff --git a/clang/test/Analysis/out-of-bounds.c b/clang/test/Analysis/out-of-bounds.c index 1f771c2b3bd138..9b9cc368af94dc 100644 --- a/clang/test/Analysis/out-of-bounds.c +++ b/clang/test/Analysis/out-of-bounds.c @@ -1,4 +1,4 @@ -// RUN: %clang_analyze_cc1 -Wno-array-bounds -analyzer-checker=core,alpha.security.ArrayBoundV2,debug.ExprInspection -verify %s +// RUN: %clang_analyze_cc1 -Wno-array-bounds -Wno-pointer-sign -analyzer-checker=core,alpha.security.ArrayBoundV2,debug.ExprInspection -verify %s void clang_analyzer_eval(int); @@ -194,3 +194,19 @@ char test_comparison_with_extent_symbol(struct incomplete *p) { return ((char *)p)[-1]; // no-warning } + +typedef unsigned char uint8_t; +static int string_is_ascii(const uint8_t *str) { + while (*str && *str < 128) str++; + // expected-warning@-1 {{Out of bound access to memory}} + return !*str; +} +void test_charptr_ucharptr_conversion(void) { + const char *s = ""; + // NOTE: This code passes a `const char *` to a `const unsigned char *` + // parameter, which is a bit dodgy (it would be reported by -Wpointer-sign), + // but works on platforms where `char` is unsigned. + // FIXME: The analyzer is confused by this conversion and cannot deduce that + // `*str` is immediately equal to zero within `string_is_ascii()`. + string_is_ascii(s); +} `````````` </details> https://github.com/llvm/llvm-project/pull/108799 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
