Could you summarize how you handle this in redo? Also what about the case where a header file does exist but is out-of-date and because of that triggers an error (e.g., version compatibility check with #error) -- how do you handle that?
JdeBP %cat test.cpp
#include <cstddef>
void f() {}
JdeBP %/package/prog/cc/command/cpp test.cpp --iapplication . --icompiler-high /usr/local/lib/gcc5/include/c++ --icompiler-low /usr/local/lib/gcc5/include/c++/x86_64-portbld-freebsd10.3 --iplatform /usr/local/include --iplatform /usr/include -MD -MF /dev/stderr 2>&1 > /dev/null|fgrep redo
redo-ifcreate ./cstddef ./bits/c++config.h /usr/local/lib/gcc5/include/c++/bits/c++config.h /usr/local/include/bits/c++config.h /usr/include/bits/c++config.h ./bits/os_defines.h /usr/local/lib/gcc5/include/c++/bits/os_defines.h /usr/local/include/bits/os_defines.h /usr/include/bits/os_defines.h ./bits/cpu_defines.h /usr/local/lib/gcc5/include/c++/bits/cpu_defines.h /usr/local/include/bits/cpu_defines.h /usr/include/bits/cpu_defines.h ./stddef.h /usr/local/lib/gcc5/include/c++/stddef.h /usr/local/include/stddef.h ./sys/cdefs.h /usr/local/lib/gcc5/include/c++/sys/cdefs.h /usr/local/include/sys/cdefs.h ./sys/_null.h /usr/local/lib/gcc5/include/c++/sys/_null.h /usr/local/include/sys/_null.h ./sys/_types.h /usr/local/lib/gcc5/include/c++/sys/_types.h /usr/local/include/sys/_types.h ./machine/_types.h /usr/local/lib/gcc5/include/c++/machine/_types.h /usr/local/include/machine/_types.h ./x86/_types.h /usr/local/lib/gcc5/include/c++/x86/_types.h /usr/local/include/x86/_types.h
redo-ifchange /usr/local/lib/gcc5/include/c++/cstddef /usr/local/lib/gcc5/include/c++/x86_64-portbld-freebsd10.3/bits/c++config.h /usr/local/lib/gcc5/include/c++/x86_64-portbld-freebsd10.3/bits/os_defines.h /usr/local/lib/gcc5/include/c++/x86_64-portbld-freebsd10.3/bits/cpu_defines.h /usr/include/stddef.h /usr/include/sys/cdefs.h /usr/include/sys/_null.h /usr/include/sys/_types.h /usr/include/machine/_types.h /usr/include/x86/_types.h
JdeBP %/package/prog/cc/command/cpp test.cpp --iapplication . --icompiler-high /usr/local/lib/gcc5/include/c++ --icompiler-low /usr/local/lib/gcc5/include/c++/x86_64-portbld-freebsd10.3 --iplatform /usr/local/include --iplatform /usr/include -MMD -MF /dev/stderr 2>&1 > /dev/null|fgrep redo
redo-ifcreate ./cstddef ./bits/c++config.h ./bits/os_defines.h ./bits/cpu_defines.h ./stddef.h ./sys/cdefs.h ./sys/_null.h ./sys/_types.h ./machine/_types.h ./x86/_types.h
redo-ifchange
JdeBP %
It's then a simple matter of invoking these redo-ifchange and redo-ifcreate commands from within the redo script that is invoking the compiler.
You can see this plumbed into redo in a real system in the source archives for the nosh toolset and djbwares.
* http://jdebp.eu./FGA/introduction-to-redo.html#CompilerDefic...
#!/bin/sh
redo-ifchange $2.c
strace -e stat,stat64,fstat,fstat64,lstat,lstat64 -f 2>&1 >/dev/null\
gcc $2.c -o $3 -MD -MF $2.deps\
|grep '1 ENOENT'\
|grep '\.h'\
|cut -d'"' -f2 2>/dev/null\
>$2.deps_ne
read d <$2.deps
redo-ifchange ${d#*:}
while read -r d_ne; do
redo-ifcreate $d_ne
done <$2.deps_ne
chmod a+x $3
I think the compiler should output the necessary information. To quote Jonathan de Boyne Pollard [3]:
> As noted earlier, no C or C++ compiler currently generates any redo-ifcreate dependency information, only the redo-ifchange dependency information. This is a deficiency of the compilers rather than a deficiency of redo, though. That the introduction of a new higher-precedence header earlier on the include path will affect recompilation is a fact that almost all C/C++ build systems fail to account for.
> I have written, but not yet released, a C++ tool that is capable of generating both redo-ifchange information for included files and redo-ifcreate information for the places where included files were searched for but didn't exist, and thus where adding new (different) included files would change the output.
JdeBP, could you please release your tool under a free software license? I suspect it has fewer errors than the similar CMake approach [4].
[1] http://news.dieweltistgarnichtso.net/posts/redo-gcc-automati...
[2] https://github.com/linleyh/liberation-circuit/blob/master/sr...
[3] http://jdebp.eu./FGA/introduction-to-redo.html#CompilerDefic...
[4] https://github.com/Kitware/CMake/blob/master/Source/cmDepend...