在 2020/11/12 18:18, Jonathan Yong 写道: > libgomp build fails because of the false -Wformat error, even though: > 1. Correct C99 inttypes.h macros are used. > 2. __mingw_* C99 wrappers are used. > 3. The printf attribute is used, but it was aliased to ms_printf > > The attached patch makes mingw-w64 printf attribute equivalent to other > platforms on C99 or later. > This allows libgomp to build again with -Werror on. This patch should not > affect the original > mingw.org distribution in any way. >
According to the conversation on IRC, I personally consider this inappropriate. Although the `ll` modifier is specified by C99 for `long long`, there are many more that don't conform to C99 without UCRT: 1. The `z` modifier for `size_t` is unrecognized. 2. The `t` modifier for `ptrdiff_t` is unrecognized. 3. The `L` modifier for `long double` is accepted but ignored due to the fact that MSABI uses an 8-byte type. > For C99 or later, the mingw-w64 headers already wrap printf/scanf properly, > and inttypes.h also > gives the correct C99 specifiers, so it makes sense to treat the printf > attribute as C99 compliant. > Under C89 mode, the headers would produce MS specific specifiers, so the > printf attribute under C89 > reverts to the old behavior of being aliased to ms_printf. > > This might break other code that assumes differently however. I don't think > there is a solution to > satisfy everyone, but at least this allows C99/C++11 compliant code to build > again with -Werror. > Comments? My humble opinion is that people should have gotten used to the `ll` specifier so I propose a different patch that enables it unconditionally. As Jonathan Yong pointed out, GCC is impossible to predict where the target executable will run. It may be reasonable to expect Vista+ instead of an ancient one. Users who still code for XP- should probably handle such differentiation themselves. In comparison, MSVC does not have such format checks at all. I started bootstrapping GCC a few minutes ago. It's not gonna finish very soon so I send this patch for your comments. -- Best regards, LH_Mouse
From 1d61adae0695e7067e35f36e607a754a7cf12796 Mon Sep 17 00:00:00 2001 From: Liu Hao <lh_mo...@126.com> Date: Thu, 12 Nov 2020 22:20:29 +0800 Subject: [PATCH] gcc: Add `ll` and `L` length modifiers for `ms_printf` Previous code abuse `FMT_LEN_L` for the `I` modifier. As `L` is a valid modifier for `f`, `e`, `g`, etc. and `I` has the same semantics as the C99 `z` modifier, `FMT_LEN_z` is now used. First, in the Microsoft ABI, type `long double` has the same layout as type `double`, so `%Lg` behaves identically to `%g`. Users should pass in `double`s instead as `long double`s, as GCC uses the 10-byte format. Second, with a CRT that is recent enough (MSVCRT since Vista, MSVCR80, UCRT, or mingw-w64 8.0), `printf`-family functions can handle the `ll` length modifier correctly. This ability is assumed to be available universally. A lot of libraries (such as libgomp) that use the `format(printf, ...)` attribute used to suffer from warnings about unknown format specifiers. Reference: https://docs.microsoft.com/en-us/previous-versions/visualstudio/visual-studio-2008/tcxf1dw6(v=vs.90) Reference: https://docs.microsoft.com/en-us/cpp/porting/visual-cpp-what-s-new-2003-through-2015#new-crt-features Signed-off-by: Liu Hao <lh_mo...@126.com> gcc/: * config/i386/msformat-c.c: Add more length modifiers --- gcc/config/i386/msformat-c.c | 45 ++++++++++++++++++------------------ 1 file changed, 23 insertions(+), 22 deletions(-) diff --git a/gcc/config/i386/msformat-c.c b/gcc/config/i386/msformat-c.c index 4ceec633a6e..1629b866976 100644 --- a/gcc/config/i386/msformat-c.c +++ b/gcc/config/i386/msformat-c.c @@ -32,10 +32,11 @@ along with GCC; see the file COPYING3. If not see static format_length_info ms_printf_length_specs[] = { { "h", FMT_LEN_h, STD_C89, NULL, FMT_LEN_none, STD_C89, 0 }, - { "l", FMT_LEN_l, STD_C89, NULL, FMT_LEN_none, STD_C89, 0 }, + { "l", FMT_LEN_l, STD_C89, NULL, FMT_LEN_ll, STD_C9L, 0 }, + { "L", FMT_LEN_L, STD_C89, NULL, FMT_LEN_none, STD_C89, 1 }, { "I32", FMT_LEN_l, STD_EXT, NULL, FMT_LEN_none, STD_C89, 1 }, { "I64", FMT_LEN_ll, STD_EXT, NULL, FMT_LEN_none, STD_C89, 1 }, - { "I", FMT_LEN_L, STD_EXT, NULL, FMT_LEN_none, STD_C89, 1 }, + { "I", FMT_LEN_z, STD_EXT, NULL, FMT_LEN_none, STD_C89, 1 }, { NULL, FMT_LEN_none, STD_C89, NULL, FMT_LEN_none, STD_C89, 0 } }; @@ -90,33 +91,33 @@ static const format_flag_pair ms_strftime_flag_pairs[] = static const format_char_info ms_print_char_table[] = { /* C89 conversion specifiers. */ - { "di", 0, STD_C89, { T89_I, BADLEN, T89_S, T89_L, T9L_LL, T99_SST, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-wp0 +'", "i", NULL }, - { "oxX", 0, STD_C89, { T89_UI, BADLEN, T89_US, T89_UL, T9L_ULL, T99_ST, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-wp0#", "i", NULL }, - { "u", 0, STD_C89, { T89_UI, BADLEN, T89_US, T89_UL, T9L_ULL, T99_ST, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-wp0'", "i", NULL }, - { "fgG", 0, STD_C89, { T89_D, BADLEN, BADLEN, T99_D, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-wp0 +#'", "", NULL }, - { "eE", 0, STD_C89, { T89_D, BADLEN, BADLEN, T99_D, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-wp0 +#", "", NULL }, - { "c", 0, STD_C89, { T89_I, BADLEN, T89_S, T94_WI, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-w", "", NULL }, - { "s", 1, STD_C89, { T89_C, BADLEN, T89_S, T94_W, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-wp", "cR", NULL }, - { "p", 1, STD_C89, { T89_V, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-w", "c", NULL }, - { "n", 1, STD_C89, { T89_I, BADLEN, T89_S, T89_L, T9L_LL, BADLEN, BADLEN, BADLEN, T99_IM, BADLEN, BADLEN, BADLEN }, "", "W", NULL }, + { "di", 0, STD_C89, { T89_I, BADLEN, T89_S, T89_L, T9L_LL, BADLEN, T99_SST, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-wp0 +'", "i", NULL }, + { "oxX", 0, STD_C89, { T89_UI, BADLEN, T89_US, T89_UL, T9L_ULL, BADLEN, T99_ST, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-wp0#", "i", NULL }, + { "u", 0, STD_C89, { T89_UI, BADLEN, T89_US, T89_UL, T9L_ULL, BADLEN, T99_ST, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-wp0'", "i", NULL }, + { "fgG", 0, STD_C89, { T89_D, BADLEN, BADLEN, T99_D, BADLEN, T89_D, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-wp0 +#'", "", NULL }, + { "eE", 0, STD_C89, { T89_D, BADLEN, BADLEN, T99_D, BADLEN, T89_D, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-wp0 +#", "", NULL }, + { "c", 0, STD_C89, { T89_I, BADLEN, T89_S, T94_WI, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-w", "", NULL }, + { "s", 1, STD_C89, { T89_C, BADLEN, T89_S, T94_W, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-wp", "cR", NULL }, + { "p", 1, STD_C89, { T89_V, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-w", "c", NULL }, + { "n", 1, STD_C89, { T89_I, BADLEN, T89_S, T89_L, T9L_LL, BADLEN, BADLEN, BADLEN, T99_IM, BADLEN, BADLEN, BADLEN }, "", "W", NULL }, /* X/Open conversion specifiers. */ - { "C", 0, STD_EXT, { TEX_WI, BADLEN, T89_S, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-w", "", NULL }, - { "S", 1, STD_EXT, { TEX_W, BADLEN, T89_S, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-wp", "R", NULL }, + { "C", 0, STD_EXT, { TEX_WI, BADLEN, T89_S, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-w", "", NULL }, + { "S", 1, STD_EXT, { TEX_W, BADLEN, T89_S, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "-wp", "R", NULL }, { NULL, 0, STD_C89, NOLENGTHS, NULL, NULL, NULL } }; static const format_char_info ms_scan_char_table[] = { /* C89 conversion specifiers. */ - { "di", 1, STD_C89, { T89_I, BADLEN, T89_S, T89_L, T9L_LL, T99_SST, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*w'", "W", NULL }, - { "u", 1, STD_C89, { T89_UI, BADLEN, T89_US, T89_UL, T9L_ULL, T99_ST, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*w'", "W", NULL }, - { "oxX", 1, STD_C89, { T89_UI, BADLEN, T89_US, T89_UL, T9L_ULL, T99_ST, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*w", "W", NULL }, - { "efgEG", 1, STD_C89, { T89_F, BADLEN, BADLEN, T89_D, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*w'", "W", NULL }, - { "c", 1, STD_C89, { T89_C, BADLEN, T89_S, T94_W, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*w", "cW", NULL }, - { "s", 1, STD_C89, { T89_C, BADLEN, T89_S, T94_W, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*aw", "cW", NULL }, - { "[", 1, STD_C89, { T89_C, BADLEN, BADLEN, T94_W, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*aw", "cW[", NULL }, - { "p", 2, STD_C89, { T89_V, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*w", "W", NULL }, - { "n", 1, STD_C89, { T89_I, BADLEN, T89_S, T89_L, T9L_LL, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "", "W", NULL }, + { "di", 1, STD_C89, { T89_I, BADLEN, T89_S, T89_L, T9L_LL, BADLEN, T99_SST, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*w'", "W", NULL }, + { "u", 1, STD_C89, { T89_UI, BADLEN, T89_US, T89_UL, T9L_ULL, BADLEN, T99_ST, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*w'", "W", NULL }, + { "oxX", 1, STD_C89, { T89_UI, BADLEN, T89_US, T89_UL, T9L_ULL, BADLEN, T99_ST, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*w", "W", NULL }, + { "efgEG", 1, STD_C89, { T89_F, BADLEN, BADLEN, T89_D, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*w'", "W", NULL }, + { "c", 1, STD_C89, { T89_C, BADLEN, T89_S, T94_W, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*w", "cW", NULL }, + { "s", 1, STD_C89, { T89_C, BADLEN, T89_S, T94_W, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*aw", "cW", NULL }, + { "[", 1, STD_C89, { T89_C, BADLEN, BADLEN, T94_W, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*aw", "cW[", NULL }, + { "p", 2, STD_C89, { T89_V, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*w", "W", NULL }, + { "n", 1, STD_C89, { T89_I, BADLEN, T89_S, T89_L, T9L_LL, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "", "W", NULL }, /* X/Open conversion specifiers. */ { "C", 1, STD_EXT, { TEX_W, BADLEN, T89_S, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*w", "W", NULL }, { "S", 1, STD_EXT, { TEX_W, BADLEN, T89_S, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "*aw", "W", NULL }, -- 2.20.1
