This option is enabled by default when -Wformat option is enabled. A user can specify -Wno-format-same-precision to disable emitting warnings about an argument passed to printf-like function having a different type from the one specified in the format string if the types precisions are the same.
Signed-off-by: Daniil Stas <daniil.s...@posteo.net> gcc/c-family/ChangeLog: * c-format.c (check_format_types): Don't emit warnings about type differences with the format string if -Wno-format-same-precision is specified and the types have the same precision. * c.opt: Add -Wformat-same-precision option. gcc/ChangeLog: * doc/invoke.texi: Add -Wformat-same-precision option description. gcc/testsuite/ChangeLog: * c-c++-common/Wformat-same-precision-1.c: New test. * c-c++-common/Wformat-same-precision-2.c: New test. --- gcc/c-family/c-format.c | 2 +- gcc/c-family/c.opt | 5 +++++ gcc/doc/invoke.texi | 8 +++++++- gcc/testsuite/c-c++-common/Wformat-same-precision-1.c | 7 +++++++ gcc/testsuite/c-c++-common/Wformat-same-precision-2.c | 7 +++++++ 5 files changed, 27 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/c-c++-common/Wformat-same-precision-1.c create mode 100644 gcc/testsuite/c-c++-common/Wformat-same-precision-2.c diff --git a/gcc/c-family/c-format.c b/gcc/c-family/c-format.c index b4cb765a9d3..07cdcefbef8 100644 --- a/gcc/c-family/c-format.c +++ b/gcc/c-family/c-format.c @@ -4243,7 +4243,7 @@ check_format_types (const substring_loc &fmt_loc, && (!pedantic || i < 2) && char_type_flag) continue; - if (types->scalar_identity_flag + if ((types->scalar_identity_flag || !warn_format_same_precision) && (TREE_CODE (cur_type) == TREE_CODE (wanted_type) || (INTEGRAL_TYPE_P (cur_type) && INTEGRAL_TYPE_P (wanted_type))) diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt index 9c151d19870..e7af7365c91 100644 --- a/gcc/c-family/c.opt +++ b/gcc/c-family/c.opt @@ -656,6 +656,11 @@ C ObjC C++ LTO ObjC++ Warning Alias(Wformat-overflow=, 1, 0) IntegerRange(0, 2) Warn about function calls with format strings that write past the end of the destination region. Same as -Wformat-overflow=1. +Wformat-same-precision +C ObjC C++ ObjC++ Var(warn_format_same_precision) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=,warn_format >= 1, 0) +Warn about type differences with the format string even if the types +precision is the same. + Wformat-security C ObjC C++ ObjC++ Var(warn_format_security) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 2, 0) Warn about possible security problems with format functions. diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index ba98eab68a5..8833f257d75 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -347,7 +347,7 @@ Objective-C and Objective-C++ Dialects}. -Werror -Werror=* -Wexpansion-to-defined -Wfatal-errors @gol -Wfloat-conversion -Wfloat-equal -Wformat -Wformat=2 @gol -Wno-format-contains-nul -Wno-format-extra-args @gol --Wformat-nonliteral -Wformat-overflow=@var{n} @gol +-Wformat-nonliteral -Wformat-overflow=@var{n} -Wformat-same-precision @gol -Wformat-security -Wformat-signedness -Wformat-truncation=@var{n} @gol -Wformat-y2k -Wframe-address @gol -Wframe-larger-than=@var{byte-size} -Wno-free-nonheap-object @gol @@ -6054,6 +6054,12 @@ If @option{-Wformat} is specified, also warn if the format string is not a string literal and so cannot be checked, unless the format function takes its format arguments as a @code{va_list}. +@item -Wformat-same-precision +@opindex Wformat-same-precision +@opindex Wno-format-same-precision +If @option{-Wformat} is specified, warn about type differences with the format +string even if the types precision is the same. + @item -Wformat-security @opindex Wformat-security @opindex Wno-format-security diff --git a/gcc/testsuite/c-c++-common/Wformat-same-precision-1.c b/gcc/testsuite/c-c++-common/Wformat-same-precision-1.c new file mode 100644 index 00000000000..fbc11e4200a --- /dev/null +++ b/gcc/testsuite/c-c++-common/Wformat-same-precision-1.c @@ -0,0 +1,7 @@ +/* { dg-do compile { target lp64 } } */ +/* { dg-options "-Wformat" } */ + +void test () +{ + __builtin_printf ("%lu\n", (long long) 1); /* { dg-warning "expects argument of type" } */ +} diff --git a/gcc/testsuite/c-c++-common/Wformat-same-precision-2.c b/gcc/testsuite/c-c++-common/Wformat-same-precision-2.c new file mode 100644 index 00000000000..17e643e0441 --- /dev/null +++ b/gcc/testsuite/c-c++-common/Wformat-same-precision-2.c @@ -0,0 +1,7 @@ +/* { dg-do compile { target lp64 } } */ +/* { dg-options "-Wformat -Wno-format-same-precision" } */ + +void test () +{ + __builtin_printf ("%lu\n", (long long) 1); /* { ! dg-warning "expects argument of type" } */ +} -- 2.33.0