[GCC][Windows] header file inclusion on windows

[David Brown]

On 28/01/2023 04:57, Mena Makary via Gcc-help wrote:
> Hello GCC Help Team,
> 
> Could you please support on the following C code example:
> 
> #include "header.h"   /* Proper file name like on windows file system, No
> error is expected */
> #include "Header.h"  /* Same file but H letter is camelcased by mistake,
> Error is expected */
> #include "header.h "  /* Same file but a space is added before end of file
> inclusion by mistake, Error is expected */
> 
> The problem here is that the above two issues are not detected by GCC
> on windows, while could be detected on Linux.
> Is there any compiler option/flag enables GCC to detect such issues on
> Windows?
> 

I think this is inevitable for Windows.  The compiler will ask for the 
header by trying to open a file called "header.h", "Header.h" or 
"header.h ", and the OS will give them file, because on Windows these 
all refer to the same file due to case-insensitive and space-striping 
names.  So the compiler has no way to report this as an issue - because 
on Windows, it is /not/ an error.  It is the expected behaviour of the 
system.

In theory, I suppose, the compiler could ask for a details of the file 
or a directory listing, and compare the stored name (as file names are 
case-preserving in Windows) to the name requested by the pre-processor. 
But that would be a lot of extra work for no purpose for a compiler, and 
would break code that currently compiles fine on Windows.

I don't know what you are aiming to do here.  But one possibility is to 
use one of the "-M" options for gcc to create a "make" dependency file 
that lists the headers included by the file.  A small Python script 
could parse that, read the true filename for the file on the Windows 
filesystem, and compare them.

Another possibility is to run the compilation using a Cygwin 
environment, rather than more common mingw gcc builds.  Under Cygwin, 
filenames are case sensitive.