Question

I have a header in my project, called Core.h, that I use as a pre-compiled header:

$(CXX) $(CXX_CFLAGS) -x c++-header Core.h

Which creates a file named Core.h.gch

*#include "Core.h" is the first directive of every source file in the module.

On OS X, it works fine — my project compiles fine & it compiles pretty fast.

On Linux however, 7 of my 100+ files give the following warning:

warning: Core.h.gch: too short to be a PCH file

Just like every other source file, #include "Core.h" is the first line of these files.

Has anyone ever come across this? Possible causes? Why would it only be a few files that include the PCH that would give the warning ?

I use gcc version 4.1.2 on Linux, 4.2.1 on OSX

Thanks!

EDIT:

Here is basically how I build the library:

.PHONY: all 
all: $(MY_PCH) MYLIB.so MYLIB.a

MYLIB.so: $(MY_PCH) $(MY_OBJECTS)
  $(CXX) $(MY_OBJECTS) $(CXX_LDFLAGS) -o $@

MYLIB.a: $(MY_PCH) $(MY_OBJECTS)
  $(AR) $(ARFLAGS) $@ $(MY_OBJECTS)

$(MY_PCH):
  $(CXX) $(CXX_CFLAGS) -x c++-header Core.h

Answer 1

Are you using a parallel make? Possibly g++ is trying to read the .gch file while another instance is writing to it.