用Cygwin构建Assimp

Question

我想用cmake和cygwin来构建Assimp。

根据cmake文档，cmake有7个Makefile生成器：

Borland Makefiles
MSYS Makefiles
MinGW Makefiles
NMake Makefiles
NMake Makefiles JOM
Unix Makefiles
Watcom WMake

但是没有任何针对cygwin的Makefile生成器。

如何使用cygwin构建Assimp？

Answer 1

在cygwin的基础上，strcasecmp上有一个问题

/pub/tmp/assimp-5.0.1/include/assimp/StringComparison.h:146:14: error: ‘::strcasecmp’ has not been declared; did you mean ‘strncmp’?
  146 |     return ::strcasecmp(s1,s2);
      |              ^~~~~~~~~~
      |              strncmp

https://pubs.opengroup.org/onlinepubs/9699919799/functions/strcasecmp.html

这是因为Cygwin仍然认为它是一个扩展

第二个问题来自复杂的C++模板

[ 37%] Building CXX object code/CMakeFiles/assimp.dir/Importer/IFC/IFCReaderGen1_2x3.cpp.o
/usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/as: CMakeFiles/assimp.dir/Importer/IFC/IFCReaderGen1_2x3.cpp.o: too many sections (88485)
/tmp/cc95KPdy.s: Assembler messages:
/tmp/cc95KPdy.s: Fatal error: can't write 180 bytes to section .text of CMakeFiles/assimp.dir/Importer/IFC/IFCReaderGen1_2x3.cpp.o: 'file too big'

我们可以从以下几个方面获取解决方案：

https://digitalkarabela.com/mingw-w64-how-to-fix-file-too-big-too-many-sections/

第三个问题是

/usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/as: CMakeFiles/assimp.dir/Importer/StepFile/StepFileGen1.cpp.o: section .xdata$_ZNSt11_Tuple_implILm1EJSt14default_deleteIN6Assimp8StepFile31draughting_callout_relationshipEEEE7_M_headERS5_: string table overflow at offset 10000005
/tmp/ccNl78l4.s: Assembler messages:
/tmp/ccNl78l4.s: Fatal error: can't close CMakeFiles/assimp.dir/Importer/StepFile/StepFileGen1.cpp.o: file too big

和使用-O1的建议

gcc string table overflow error during compilation

很管用。

通过所有这些，我们可以：

tar -xf assimp-5.0.1.tar.gz
cd assimp-5.0.1
cmake -DCMAKE_CXX_FLAGS="-D_GNU_SOURCE -Wa,-mbig-obj -O1" -DCMAKE_C_FLAGS="-D_GNU_SOURCE -Wa,-mbig-obj -O1" .
make

最后

....
[100%] Linking CXX executable ../bin/unit.exe
[100%] Built target unit