GCC warnings if [-Wshadow] is enabled.

[Remotion]

In file included from \test\warnings_test.cpp:3:0:
fmt/format.h: In function 'Char* fmt::v5::internal::format_decimal(Char*, UInt, unsigned int, ThousandsSep)':
fmt/format.h:1081:55: warning: declaration of 'buffer' shadows a global declaration [-Wshadow]
                             ThousandsSep thousands_sep) {
                                                       ^
In file included from fmt/format.h:67:0,
                 from \test\warnings_test.cpp:3:
fmt/core.h:390:28: note: shadowed declaration is here
 typedef basic_buffer<char> buffer;
                            ^~~~~~
In file included from \test\warnings_test.cpp:3:0:
fmt/format.h: In function 'Iterator fmt::v5::internal::format_decimal(Iterator, UInt, unsigned int, ThousandsSep)':
fmt/format.h:1111:59: warning: declaration of 'buffer' shadows a global declaration [-Wshadow]
   char_type buffer[std::numeric_limits<UInt>::digits10 + 2];
                                                           ^
In file included from fmt/format.h:67:0,
                 from \test\warnings_test.cpp:3:
fmt/core.h:390:28: note: shadowed declaration is here
 typedef basic_buffer<char> buffer;
                            ^~~~~~
In file included from \test\warnings_test.cpp:3:0:
fmt/format.h: In function 'Char* fmt::v5::internal::format_uint(Char*, UInt, unsigned int, bool)':
fmt/format.h:1123:44: warning: declaration of 'buffer' shadows a global declaration [-Wshadow]
                          bool upper = false) {
                                            ^
In file included from fmt/format.h:67:0,
                 from \test\warnings_test.cpp:3:
fmt/core.h:390:28: note: shadowed declaration is here
 typedef basic_buffer<char> buffer;
                            ^~~~~~
In file included from \test\warnings_test.cpp:3:0:
fmt/format.h: In function 'It fmt::v5::internal::format_uint(It, UInt, unsigned int, bool)':
fmt/format.h:1139:64: warning: declaration of 'buffer' shadows a global declaration [-Wshadow]
   char buffer[std::numeric_limits<UInt>::digits / BASE_BITS + 2];
                                                                ^
In file included from fmt/format.h:67:0,
                 from \test\warnings_test.cpp:3:
fmt/core.h:390:28: note: shadowed declaration is here
 typedef basic_buffer<char> buffer;
                            ^~~~~~
In file included from \test\warnings_test.cpp:3:0:
fmt/format.h: In constructor 'constexpr fmt::v5::internal::arg_ref<Char>::arg_ref(unsigned int)':
fmt/format.h:1913:50: warning: declaration of 'index' shadows a member of 'fmt::v5::internal::arg_ref<Char>' [-Wshadow]
   FMT_CONSTEXPR explicit arg_ref(unsigned index) : kind(INDEX), index(index) {}
                                                  ^
fmt/format.h:1924:14: note: shadowed declaration is here
     unsigned index;
              ^~~~~
fmt/format.h: In constructor 'fmt::v5::internal::arg_ref<Char>::arg_ref(fmt::v5::basic_string_view<Char>)':
fmt/format.h:1914:50: warning: declaration of 'name' shadows a member of 'fmt::v5::internal::arg_ref<Char>' [-Wshadow]
   explicit arg_ref(basic_string_view<Char> name) : kind(NAME), name(name) {}
                                                  ^
fmt/format.h:1925:29: note: shadowed declaration is here
     basic_string_view<Char> name;
                             ^~~~
fmt/format.h: In member function 'constexpr typename ParseContext::iterator fmt::v5::formatter<T, Char, typename std::enable_if<fmt::v5::internal::format_type<typename fmt::v5::buffer_context<Char>::type, T>::value>::type>::parse(ParseContext&)':
fmt/format.h:3175:10: warning: declaration of 'type_spec' shadows a global declaration [-Wshadow]
     auto type_spec = specs_.type();
          ^~~~~~~~~
fmt/format.h:1275:37: note: shadowed declaration is here
 typedef format_spec<char, type_tag> type_spec;
                                     ^~~~~~~~~
fmt/format.h: In constructor 'fmt::v5::arg_join<It, Char>::arg_join(It, It, fmt::v5::basic_string_view<Char>)':
fmt/format.h:3405:5: warning: declaration of 'sep' shadows a member of 'fmt::v5::arg_join<It, Char>' [-Wshadow]
     : begin(begin), end(end), sep(sep) {}
     ^
fmt/format.h:3402:27: note: shadowed declaration is here
   basic_string_view<Char> sep;
                           ^~~
fmt/format.h:3405:5: warning: declaration of 'end' shadows a member of 'fmt::v5::arg_join<It, Char>' [-Wshadow]
     : begin(begin), end(end), sep(sep) {}
     ^
fmt/format.h:3401:6: note: shadowed declaration is here
   It end;
      ^~~
fmt/format.h:3405:5: warning: declaration of 'begin' shadows a member of 'fmt::v5::arg_join<It, Char>' [-Wshadow]
     : begin(begin), end(end), sep(sep) {}
     ^
fmt/format.h:3400:6: note: shadowed declaration is here
   It begin;
      ^~~~~
In file included from fmt/format.h:3736:0,
                 from \test\warnings_test.cpp:3:
fmt/format-inl.h: In static member function 'static int fmt::v5::internal::char_traits<char>::format_float(char*, std::size_t, const char*, int, T)':
fmt/format-inl.h:226:79: warning: declaration of 'buffer' shadows a global declaration [-Wshadow]
     char *buffer, std::size_t size, const char *format, int precision, T value) {
                                                                               ^
In file included from fmt/format.h:67:0,
                 from \test\warnings_test.cpp:3:
fmt/core.h:390:28: note: shadowed declaration is here
 typedef basic_buffer<char> buffer;
                            ^~~~~~
In file included from fmt/format.h:3736:0,
                 from \test\warnings_test.cpp:3:
fmt/format-inl.h: In static member function 'static int fmt::v5::internal::char_traits<wchar_t>::format_float(wchar_t*, std::size_t, const wchar_t*, int, T)':
fmt/format-inl.h:235:12: warning: declaration of 'buffer' shadows a global declaration [-Wshadow]
     T value) {
            ^
In file included from fmt/format.h:67:0,
                 from \test\warnings_test.cpp:3:
fmt/core.h:390:28: note: shadowed declaration is here
 typedef basic_buffer<char> buffer;

[eliaskosunen]

I assume you're only including <core.h>, because -Wshadow is explicitly disabled here:

fmt/include/fmt/format.h

Lines 54 to 65 in 1b8a7f8

	#if (defined(__GNUC__) && !defined(__clang__) && __GNUC__ >= 406) || \
	FMT_CLANG_VERSION
	# pragma GCC diagnostic push
	// Disable the warning about declaration shadowing because it affects too
	// many valid cases.
	# pragma GCC diagnostic ignored "-Wshadow"
	// Disable the warning about implicit conversions that may change the sign of
	// an integer; silencing it otherwise would require many explicit casts.
	# pragma GCC diagnostic ignored "-Wsign-conversion"
	#endif

[Remotion]

No.

#define FMT_HEADER_ONLY
#include "fmt/format.h"

int main() {
    std::string ss = "string";
    fmt::format("{} \n", ss);

    return 0;
}

[eliaskosunen]

Can't reproduce in CE: https://godbolt.org/g/gqstpW
What version of gcc are you using and are you sure that the version of fmt is post- 691a7a9 ?

[Remotion]

GCC 7.3 from here https://nuwen.net/mingw.html

g++ -std=c++1z -pipe -Wall -Wextra -Wshadow -Wreturn-type -fconcepts -fstrong-eval-order -faligned-new -march=native

{fmt} is 1b8a7f8 commit.

[eliaskosunen]

I think this might be an issue with MinGW rather than fmt, as I still can't reproduce with gcc 7.3 and with the same compiler flags: https://godbolt.org/g/tnNB8T

Does anyone have gcc 7.3 installed locally so they can verify?

What values are __GNUC__ and __clang__ defined to in your platform when compiling with those settings?

[Remotion]

__GNUC__ is 7 and __clang__ is not defined.

So test __GNUC__ >= 406 will be false.

AS it described here https://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html.

If I change this test to __GNUC__ >= 4 then all the warnings disappear.

[eliaskosunen]

You're correct, that comparison is incorrect. The proper expression would be (__GNUC__ * 100 + __GNUC_MINOR__) >= 406. You could probably submit a PR.

[vitaut]

Fixed in 47268ec.

[0x8000-0000]

There are still shadow warnings in e37d6a9 with GCC 8.2

In file included from /home/florin/work/geometry/external/lib/fmt/src/format.cc:8:
/home/florin/work/geometry/external/lib/fmt/include/fmt/format-inl.h: In function ‘bool fmt::v5::internal::grisu2_gen_digits(char*, size_t&, uint32_t, uint64_t, int&, uint64_t, const fmt::v5::internal::fp&, const fmt::v5::internal::fp&, size_t)’:
/home/florin/work/geometry/external/lib/fmt/include/fmt/format-inl.h:484:69: error: declaration of ‘buffer’ shadows a global declaration [-Werror=shadow]
uint64_t delta, const fp &one, const fp &diff, size_t max_digits) {
^
In file included from /home/florin/work/geometry/external/lib/fmt/include/fmt/format.h:60,
from /home/florin/work/geometry/external/lib/fmt/include/fmt/format-inl.h:11,
from /home/florin/work/geometry/external/lib/fmt/src/format.cc:8:
/home/florin/work/geometry/external/lib/fmt/include/fmt/core.h:289:28: note: shadowed declaration is here
typedef basic_buffer buffer;
^~~~~~

[vitaut]

AFAICS shadowing warnings are suppressed.

[0x8000-0000]

/usr/bin/g++ -I/home/florin/work/geometry/external/lib/fmt/include -Wall -Wextra -Werror -pedantic -Wconversion -Wunused -Wshadow -g -std=c++17 -MD -MT external/lib/fmt/CMakeFiles/fmt.dir/src/format.cc.o -MF external/lib/fmt/CMakeFiles/fmt.dir/src/format.cc.o.d -o external/lib/fmt/CMakeFiles/fmt.dir/src/format.cc.o -c /home/florin/work/geometry/external/lib/fmt/src/format.cc

Will produce the warnings above, with GCC 8.2

[vitaut]

I see, the suppression doesn't apply in that case. Should be fixed in fa1d4db.

[0x8000-0000]

I see, the suppression doesn't apply in that case. Should be fixed in fa1d4db.

Confirmed. Thank you!