Author: Ziqing Luo Date: 2026-02-02T11:51:18-08:00 New Revision: a86202e82f040a62a346e173a9d3d1826146b9b2
URL: https://github.com/llvm/llvm-project/commit/a86202e82f040a62a346e173a9d3d1826146b9b2 DIFF: https://github.com/llvm/llvm-project/commit/a86202e82f040a62a346e173a9d3d1826146b9b2.diff LOG: [clang] __builtin_os_log_format has incorrect PrintfFormat Attribute argument (#178320) The format string is the 2nd argument of __builtin_os_log_format, thus has index 1 instead of 0 in 0-based indexing. The incorrect format attribute argument causes false positive -Wunsafe-buffer-usage-in-format-attr-call warnings. rdar://169043228 Added: clang/test/SemaCXX/warn-unsafe-buffer-usage-format-attr-builtins.cpp Modified: clang/docs/ReleaseNotes.rst clang/include/clang/Basic/Builtins.td Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 1b4c9ae3003b1..7dc6881ed43e6 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -242,6 +242,7 @@ Bug Fixes to AST Handling Miscellaneous Bug Fixes ^^^^^^^^^^^^^^^^^^^^^^^ +- Fixed the arguments of the format attribute on ``__builtin_os_log_format``. Previously, they were off by 1. Miscellaneous Clang Crashes Fixed ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/include/clang/Basic/Builtins.td b/clang/include/clang/Basic/Builtins.td index a410a138836eb..9a21d863127a2 100644 --- a/clang/include/clang/Basic/Builtins.td +++ b/clang/include/clang/Basic/Builtins.td @@ -4970,8 +4970,7 @@ def OSLogFormatBufferSize : Builtin { def OSLogFormat : Builtin { let Spellings = ["__builtin_os_log_format"]; - // FIXME: The printf attribute looks suspiciously like it should be argument #1. - let Attributes = [PrintfFormat<0>, NoThrow, CustomTypeChecking]; + let Attributes = [PrintfFormat<1>, NoThrow, CustomTypeChecking]; let Prototype = "void*(void*, char const*, ...)"; } diff --git a/clang/test/SemaCXX/warn-unsafe-buffer-usage-format-attr-builtins.cpp b/clang/test/SemaCXX/warn-unsafe-buffer-usage-format-attr-builtins.cpp new file mode 100644 index 0000000000000..71426aa9ef992 --- /dev/null +++ b/clang/test/SemaCXX/warn-unsafe-buffer-usage-format-attr-builtins.cpp @@ -0,0 +1,31 @@ +// RUN: %clang_cc1 -Wformat -verify=expected-format %s +// RUN: %clang_cc1 -Wunsafe-buffer-usage -Wunsafe-buffer-usage-in-format-attr-call -verify=expected,expected-format %s + +namespace std { + template<typename T> + struct basic_string { + T* p; + T *c_str(); + T *data(); + unsigned size_bytes(); + unsigned size(); + }; + + typedef basic_string<char> string; +} // namespace std + +// PR#178320 corrects the format attribute arguments for +// '__builtin_os_log_format' so that +// '-Wunsafe-buffer-usage-in-format-attr-call' behaves correctly on +// them. For '-Wformat', the check for '__builtin_os_log_format' is +// hand-craft without using the attribute. So they are still fine. + +void test_format_attr(char * Str, std::string StdStr) { + __builtin_os_log_format(nullptr, "hello", Str); // expected-format-warning{{data argument not used by format string}} + __builtin_os_log_format(nullptr, "hello %s", StdStr.c_str()); + __builtin_os_log_format(nullptr, "hello %s", Str); // expected-warning{{formatting function '__builtin_os_log_format' is unsafe}} \ + expected-note{{string argument is not guaranteed to be null-terminated}} + + __builtin_os_log_format(nullptr, "hello %"); // expected-format-warning{{incomplete format specifier}} + __builtin_os_log_format(nullptr, "hello %d", .42); // expected-format-warning{{format specifies type 'int' but the argument has type 'double'}} +} _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
