[cfe-dev] clang warns on libcxx chrono and string usage of user-defined literals

[Marshall Clow]

On Sep 30, 2013, at 11:48 PM, Yaron Keren <yaron.keren at gmail.com> wrote:

> Hi,
> 
> Trying to compile libcxx using ToT clang results in several warnings such as:
> 
> libcxx/string:4169:24: warning: user-defined literal suffixes not starting with '_' are reserved
>     basic_string<char> operator "" s( const char *__str, size_t __len )
> 
> libcxx/chrono:955:29: warning: user-defined literal suffixes not starting with '_' are reserved
>     constexpr chrono::hours operator"" h(unsigned long long __h)
>                        ^
> debugging, I see Sema::CheckLiteralOperatorDeclaration calling NumericLiteralParser::isValidUDSuffix which returns true (valid) for the "s" and "h" suffixes.  This prevents the second optional part of the warning, "no literal will invoke this operator" but not the first one shown above.

I'm not seeing this at all  (on Mac OS).

I just built ToT clang and then built libc++ - no warnings.
Then I tried just building individual source files from libc++ to check. No warnings either.

$ /Sources/LLVM/build/llvm-cmake-nodebug/bin/clang++ --version
clang version 3.4 (trunk 191753)
Target: x86_64-apple-darwin12.5.0
Thread model: posix
$ 
$ cd /Sources/LLVM/libcxx/lib
$ TRIPLE=-apple- CXX=$LLVM/build/llvm-cmake-nodebug/bin/clang++ ./buildit
[ output snipped; but no warnings ]
$
$ TRIPLE=-apple- CXX=$LLVM/build/llvm-cmake-nodebug/bin/clang++ ./buildit14
[ buildit14 is a copy of buildit that sets "-std=c++1y" instead of "-std=c++11" ]
[ output snipped; but no warnings ]
$
$/Sources/LLVM/build/llvm-cmake-nodebug/bin/clang++ -c -g -Os -arch i386 -arch x86_64 -nostdinc++ -std=c++11 -fstrict-aliasing -Wall -Wextra -Wshadow -Wconversion -Wnewline-eof -Wpadded -Wmissing-prototypes -Wstrict-aliasing=2 -Wstrict-overflow=4 -I../include ../src/chrono.cpp
$
$ /Sources/LLVM/build/llvm-cmake-nodebug/bin/clang++ -c -g -Os -arch i386 -arch x86_64 -nostdinc++ -std=c++1y -fstrict-aliasing -Wall -Wextra -Wshadow -Wconversion -Wnewline-eof -Wpadded -Wmissing-prototypes -Wstrict-aliasing=2 -Wstrict-overflow=4 -I../include ../src/chrono.cpp
$


-- Marshall

Marshall Clow     Idio Software   <mailto:mclow.lists at gmail.com>

A.D. 1517: Martin Luther nails his 95 Theses to the church door and is promptly moderated down to (-1, Flamebait).
        -- Yu Suzuki

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