[Bug c/30692] New: GCC automatically fails to preprocess files with the "hpp" file extension

[Bug c/30692] New: GCC automatically fails to preprocess files with the "hpp" file extension

[k04jg02 at kzoo dot edu]

I want to use gcc's -E option to just have the preprocessor run on one of my
header files, to see if some macros expand correctly. GCC will do this happily
if the file's extension is .h, but not if it is .hpp. You can see this
trivially by typing in at the console:

$ touch blah.hpp
$ gcc -E blah.hpp
gcc: blah.hpp: linker input file unused because linking not done

I think this is because gcc uses the file extension to determine that you
probably want to compile C++ and so tries to link the libstdc++. But if you use
-E you don't want to link anything! You're just trying to use the preprocessor
to see if your macros are working. Renaming the file to have a ".h" extension
fixes the problem. Using g++ instead of gcc gives the same error.

I'm using gcc on Ubuntu Edgy, here's the --version line:

gcc (GCC) 4.1.2 20060928 (prerelease) (Ubuntu 4.1.1-13ubuntu5)
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


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           Summary: GCC automatically fails to preprocess files with the
                    "hpp" file extension
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: k04jg02 at kzoo dot edu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30692

[Bug c/30692] GCC automatically fails to preprocess files with the "hpp" file extension

[schwab at suse dot de]

------- Comment #1 from schwab at suse dot de  2007-02-03 15:15 -------
.hpp is not a recognized extension.  If you want the file to be treated as a
C++ header precede it with `-xc++-header'.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30692

[Bug c/30692] GCC automatically fails to preprocess files with the "hpp" file extension

[k04jg02 at kzoo dot edu]

------- Comment #2 from k04jg02 at kzoo dot edu  2007-02-03 17:50 -------
Erm, why does it matter whether or not it's somehow officially recognized? If I
tell GCC to run the C preprocessor on it, it shouldn't matter if I decide to
make my file extension ".cow". Also, .hpp is a very common extension for C++
projects, it seems silly for it not to be recognized.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30692

[Bug c/30692] GCC automatically fails to preprocess files with the "hpp" file extension

[tromey at gcc dot gnu dot org]

------- Comment #3 from tromey at gcc dot gnu dot org  2007-02-03 19:44 -------
I think it matters because there are minor preprocessing differences
between languages.

I do agree that .hpp should be recognized.
That is PR 13676.  I'm going to close this as a duplicate.


*** This bug has been marked as a duplicate of 13676 ***


-- 

tromey at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |DUPLICATE


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30692