llvmbot
commented
2 weeks ago @llvm/issue-subscribers-clang-frontend
Author: Mario Song (MarJoSong)
I got a preprocessor error when I use intel openmp（aka iomp） libarary. There is also a header file named ‘float.h’ in iomp include dirs. The header file has different implement and not define '_LIBCPP_FLOAT_H' macro. I use a demo code to show the problem I ran into .
```c
// include/omp.h
#include "float.h"
```
```c
// include/float.h
// the empty file pretend to be the implement in iomp.
```
```c
// main.cpp
#include "omp.h"
#include "cfloat"
int main() {
return 0;
}
```
Save the above source code to the corresponding file and execute the preprocessing command
```sh
clang++ -I./include -v main.cpp
```
And got the following error outputs:
```sh
Apple clang version 15.0.0 (clang-1500.3.9.4)
Target: x86_64-apple-darwin23.5.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
"/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang" -cc1 -triple x86_64-apple-macosx14.0.0 -Wundef-prefix=TARGET_OS_ -Wdeprecated-objc-isa-usage -Werror=deprecated-objc-isa-usage -Werror=implicit-function-declaration -emit-obj -mrelax-all --mrelax-relocations -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name main.cpp -mrelocation-model pic -pic-level 2 -mframe-pointer=all -fno-strict-return -ffp-contract=on -fno-rounding-math -funwind-tables=2 -target-sdk-version=14.5 -fvisibility-inlines-hidden-static-local-var -target-cpu penryn -tune-cpu generic -debugger-tuning=lldb -target-linker-version 1053.12 -v -fcoverage-compilation-dir=/Users/bucheng/Documents/git/MinDLPSolver/demo -resource-dir /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/15.0.0 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk -I ./include -I/usr/local/include -internal-isystem /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1 -internal-isystem /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/local/include -internal-isystem /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/15.0.0/include -internal-externc-isystem /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include -internal-externc-isystem /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include -Wno-reorder-init-list -Wno-implicit-int-float-conversion -Wno-c99-designator -Wno-final-dtor-non-final-class -Wno-extra-semi-stmt -Wno-misleading-indentation -Wno-quoted-include-in-framework-header -Wno-implicit-fallthrough -Wno-enum-enum-conversion -Wno-enum-float-conversion -Wno-elaborated-enum-base -Wno-reserved-identifier -Wno-gnu-folding-constant -fdeprecated-macro -fdebug-compilation-dir=/Users/bucheng/Documents/git/MinDLPSolver/demo -ferror-limit 19 -stack-protector 1 -fstack-check -mdarwin-stkchk-strong-link -fblocks -fencode-extended-block-signature -fregister-global-dtors-with-atexit -fgnuc-version=4.2.1 -fno-cxx-modules -fcxx-exceptions -fexceptions -fmax-type-align=16 -fcommon -fcolor-diagnostics -clang-vendor-feature=+disableNonDependentMemberExprInCurrentInstantiation -fno-odr-hash-protocols -clang-vendor-feature=+enableAggressiveVLAFolding -clang-vendor-feature=+revert09abecef7bbf -clang-vendor-feature=+thisNoAlignAttr -clang-vendor-feature=+thisNoNullAttr -mllvm -disable-aligned-alloc-awareness=1 -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /var/folders/js/smz2v8453xj5kwrgw3w4lq880000gp/T/main-9c1059.o -x c++ main.cpp
clang -cc1 version 15.0.0 (clang-1500.3.9.4) default target x86_64-apple-darwin23.5.0
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/local/include"
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/Library/Frameworks"
#include "..." search starts here:
#include <...> search starts here:
./include
/usr/local/include
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/15.0.0/include
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks (framework directory)
End of search list.
In file included from main.cpp:3:
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cfloat:78:5: error: <cfloat> tried including <float.h> but didn't find libc++'s <float.h> header. This usually means that your header search paths are not configured properly. The header search paths should contain the C++ Standard Library headers before any C Standard Library, and you are probably using compiler flags that make that not be the case.
# error <cfloat> tried including <float.h> but didn't find libc++'s <float.h> header. \
^
1 error generated.
```
I think if c++ wrapper C header file include C header file with 'include ""' type，preprocessor will perfer to include from the directory where the current source code file is located and will avoid the error
I got a preprocessor error when I use intel openmp（aka iomp） libarary. There is also a header file named ‘float.h’ in iomp include dirs. The header file has different implement and not define '_LIBCPP_FLOAT_H' macro. I use a demo code to show the problem I ran into .
Save the above source code to the corresponding file and execute the preprocessing command
And got the following error outputs:
I think if c++ wrapper C header file include C header file with 'include ""' type，preprocessor will perfer to include from the directory where the current source code file is located and will avoid the error