From 92382d744176f230101d54f5c017bccd62770f01 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Mon, 7 Aug 2023 08:36:28 -0700 Subject: [PATCH] lib: test_scanf: Add explicit type cast to result initialization in test_number_prefix() A recent change in clang allows it to consider more expressions as compile time constants, which causes it to point out an implicit conversion in the scanf tests: lib/test_scanf.c:661:2: warning: implicit conversion from 'int' to 'unsigned char' changes value from -168 to 88 [-Wconstant-conversion] 661 | test_number_prefix(unsigned char, "0xA7", "%2hhx%hhx", 0, 0xa7, 2, check_uchar); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ lib/test_scanf.c:609:29: note: expanded from macro 'test_number_prefix' 609 | T result[2] = {~expect[0], ~expect[1]}; \ | ~ ^~~~~~~~~~ 1 warning generated. The result of the bitwise negation is the type of the operand after going through the integer promotion rules, so this truncation is expected but harmless, as the initial values in the result array get overwritten by _test() anyways. Add an explicit cast to the expected type in test_number_prefix() to silence the warning. There is no functional change, as all the tests still pass with GCC 13.1.0 and clang 18.0.0. Cc: stable@vger.kernel.org Link: https://github.com/ClangBuiltLinux/linuxq/issues/1899 Link: https://github.com/llvm/llvm-project/commit/610ec954e1f81c0e8fcadedcd25afe643f5a094e Suggested-by: Nick Desaulniers Signed-off-by: Nathan Chancellor Reviewed-by: Petr Mladek Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20230807-test_scanf-wconstant-conversion-v2-1-839ca39083e1@kernel.org --- lib/test_scanf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/test_scanf.c b/lib/test_scanf.c index b620cf7de503..a2707af2951a 100644 --- a/lib/test_scanf.c +++ b/lib/test_scanf.c @@ -606,7 +606,7 @@ static void __init numbers_slice(void) #define test_number_prefix(T, str, scan_fmt, expect0, expect1, n_args, fn) \ do { \ const T expect[2] = { expect0, expect1 }; \ - T result[2] = {~expect[0], ~expect[1]}; \ + T result[2] = { (T)~expect[0], (T)~expect[1] }; \ \ _test(fn, &expect, str, scan_fmt, n_args, &result[0], &result[1]); \ } while (0)