[libc] remove MPFR and related tests in full build (#87693)

In full build mode, the fuzzing tests fail to build. This PR disabled MPFR related tests in full build
```
[2/4] Building CXX object projects/libc/fuzzing/stdio/CMakeFiles/libc.fuzzing.stdio.printf_float_conv_fuzz.dir/printf_float_conv_fuzz.cpp.o
FAILED: projects/libc/fuzzing/stdio/CMakeFiles/libc.fuzzing.stdio.printf_float_conv_fuzz.dir/printf_float_conv_fuzz.cpp.o 
/usr/bin/clang++ -DLIBC_NAMESPACE=__llvm_libc_19_0_0_git -I/home/schrodingerzy/Documents/llvm/llvm-project/build/projects/libc/fuzzing/stdio -I/home/schrodingerzy/Documents/llvm/llvm-project/libc/fuzzing/stdio -I/home/schrodingerzy/Documents/llvm/llvm-project/libc -isystem /home/schrodingerzy/Documents/llvm/llvm-project/build/projects/libc/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -fsanitize=fuzzer -O2 -g -DNDEBUG -std=c++17 -MD -MT projects/libc/fuzzing/stdio/CMakeFiles/libc.fuzzing.stdio.printf_float_conv_fuzz.dir/printf_float_conv_fuzz.cpp.o -MF projects/libc/fuzzing/stdio/CMakeFiles/libc.fuzzing.stdio.printf_float_conv_fuzz.dir/printf_float_conv_fuzz.cpp.o.d -o projects/libc/fuzzing/stdio/CMakeFiles/libc.fuzzing.stdio.printf_float_conv_fuzz.dir/printf_float_conv_fuzz.cpp.o -c /home/schrodingerzy/Documents/llvm/llvm-project/libc/fuzzing/stdio/printf_float_conv_fuzz.cpp
In file included from /home/schrodingerzy/Documents/llvm/llvm-project/libc/fuzzing/stdio/printf_float_conv_fuzz.cpp:19:
In file included from /home/schrodingerzy/Documents/llvm/llvm-project/libc/utils/MPFRWrapper/mpfr_inc.h:21:
In file included from /usr/include/mpfr.h:53:
In file included from /usr/include/gmp.h:35:
In file included from /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/iosfwd:38:
In file included from /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/bits/requires_hosted.h:31:
In file included from /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/x86_64-pc-linux-gnu/bits/c++config.h:679:
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/x86_64-pc-linux-gnu/bits/os_defines.h:44:5: error: function-like macro '__GLIBC_PREREQ' is not defined
   44 | #if __GLIBC_PREREQ(2,15) && defined(_GNU_SOURCE)
      |     ^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/x86_64-pc-linux-gnu/bits/os_defines.h:55:5: error: function-like macro '__GLIBC_PREREQ' is not defined
   55 | #if __GLIBC_PREREQ(2, 26) \
      |     ^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/x86_64-pc-linux-gnu/bits/os_defines.h:66:6: error: function-like macro '__GLIBC_PREREQ' is not defined
   66 | # if __GLIBC_PREREQ(2, 27)
      |      ^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/x86_64-pc-linux-gnu/bits/os_defines.h:78:6: error: function-like macro '__GLIBC_PREREQ' is not defined
   78 | # if __GLIBC_PREREQ(2, 34)
      |      ^
In file included from /home/schrodingerzy/Documents/llvm/llvm-project/libc/fuzzing/stdio/printf_float_conv_fuzz.cpp:19:
In file included from /home/schrodingerzy/Documents/llvm/llvm-project/libc/utils/MPFRWrapper/mpfr_inc.h:21:
In file included from /usr/include/mpfr.h:53:
In file included from /usr/include/gmp.h:35:
In file included from /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/iosfwd:42:
In file included from /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/bits/postypes.h:40:
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:64:11: error: no member named 'mbstate_t' in the global namespace
   64 |   using ::mbstate_t;
      |         ~~^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:143:11: error: no member named 'btowc' in the global namespace
  143 |   using ::btowc;
      |         ~~^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:144:11: error: no member named 'fgetwc' in the global namespace
  144 |   using ::fgetwc;
      |         ~~^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:145:11: error: no member named 'fgetws' in the global namespace
  145 |   using ::fgetws;
      |         ~~^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:146:11: error: no member named 'fputwc' in the global namespace
  146 |   using ::fputwc;
      |         ~~^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:147:11: error: no member named 'fputws' in the global namespace
  147 |   using ::fputws;
      |         ~~^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:148:11: error: no member named 'fwide' in the global namespace
  148 |   using ::fwide;
      |         ~~^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:149:11: error: no member named 'fwprintf' in the global namespace
  149 |   using ::fwprintf;
      |         ~~^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:150:11: error: no member named 'fwscanf' in the global namespace
  150 |   using ::fwscanf;
      |         ~~^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:151:11: error: no member named 'getwc' in the global namespace
  151 |   using ::getwc;
      |         ~~^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:152:11: error: no member named 'getwchar' in the global namespace
  152 |   using ::getwchar;
      |         ~~^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:153:11: error: no member named 'mbrlen' in the global namespace
  153 |   using ::mbrlen;
      |         ~~^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:154:11: error: no member named 'mbrtowc' in the global namespace
  154 |   using ::mbrtowc;
      |         ~~^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:155:11: error: no member named 'mbsinit' in the global namespace
  155 |   using ::mbsinit;
      |         ~~^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.2.1/../../../../include/c++/13.2.1/cwchar:156:11: error: no member named 'mbsrtowcs' in the global namespace
  156 |   using ::mbsrtowcs;
      |         ~~^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
```

Author: SchrodingerZhu

libc/cmake/modules/LLVMLibCCheckMPFR.cmake

@@ -2,7 +2,9 @@ set(LLVM_LIBC_MPFR_INSTALL_PATH "" CACHE PATH "Path to where MPFR is installed (
 
 if(LLVM_LIBC_MPFR_INSTALL_PATH)
   set(LIBC_TESTS_CAN_USE_MPFR TRUE)
-elseif(LIBC_TARGET_OS_IS_GPU)
+elseif(LIBC_TARGET_OS_IS_GPU OR LLVM_LIBC_FULL_BUILD)
+  # In full build mode, the MPFR library should be built using our own facilities,
+  # which is currently not possible.
   set(LIBC_TESTS_CAN_USE_MPFR FALSE)
 else()
   try_compile(

libc/utils/MPFRWrapper/CMakeLists.txt

@@ -5,12 +5,6 @@ if(LIBC_TESTS_CAN_USE_MPFR)
     mpfr_inc.h
   )
   target_compile_options(libcMPFRWrapper PRIVATE -O3)
-  if (LLVM_LIBC_FULL_BUILD)
-    # It is not easy to make libcMPFRWrapper a standalone library because gmp.h may unconditionally
-    # pull in some STL headers. As a result, targets using this library will need to link against
-    # C++ and unwind libraries. Since we are using MPFR anyway, we directly specifies the GNU toolchain.
-    target_link_libraries(libcMPFRWrapper PUBLIC -lstdc++ -lgcc_s)
-  endif()
   add_dependencies(
     libcMPFRWrapper
     libc.src.__support.CPP.string_view
@@ -24,6 +18,6 @@ if(LIBC_TESTS_CAN_USE_MPFR)
     target_link_directories(libcMPFRWrapper PUBLIC ${LLVM_LIBC_MPFR_INSTALL_PATH}/lib)
   endif()
   target_link_libraries(libcMPFRWrapper PUBLIC LibcFPTestHelpers.unit LibcTest.unit mpfr gmp)
-elseif(NOT LIBC_TARGET_OS_IS_GPU)
+elseif(NOT LIBC_TARGET_OS_IS_GPU AND NOT LLVM_LIBC_FULL_BUILD)
   message(WARNING "Math tests using MPFR will be skipped.")
 endif()