On 9 Dec 2016 at 13:48, Andrew Donnellan wrote:

quoted

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as for the solutions, the general advice should enable the use of otherwise
failing gcc versions instead of forcing updating to new ones (though the
latter is advisable for other reasons but not everyone's in the position to
do so easily). in my experience all one needs to do is manually install the
missing files from the gcc sources (ideally distros would take care of it).

If someone else is willing to write up that advice, then great.

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the specific problem addressed here can (and IMHO should) be solved in
another way: remove the inclusion of the offending headers in gcc-common.h
as neither tm.h nor c-common.h are needed by existing plugins. for background,

We can't build without tm.h: http://pastebin.com/W0azfCr0

you'll need to repeat the removal of dependent headers. based on a quick
test here across gcc 4.5-6.2, if you remove rtl.h, tm_p.h, hard-reg-set.h
and emit-rtl.h in addition to tm.h, the plugins should build fine.

And we get warnings without c-common.h: http://pastebin.com/Aw8CAj10

that's not due to c-common.h. gcc versions 4.5-4.6 are compiled as a C program
and gcc 4.7 can be compiled both as a C and a C++ program (IIRC, distros opted
for the latter, i forget what manually built versions default to but i guess you
went with the C compilation for your gcc anyway). couple that with -Wmissing-prototypes
and you get that warning regardless of c-common.h being included. something like
this should fix it:

--- a/scripts/gcc-plugins/gcc-generate-gimple-pass.h 2016-12-06 01:01:54.521724573 +0100
+++ b/scripts/gcc-plugins/gcc-generate-gimple-pass.h      2016-12-09 11:43:32.225226164 +0100

@@ -136,6 +136,7 @@
        return new _PASS_NAME_PASS();
 }
 #else
+struct opt_pass *_MAKE_PASS_NAME_PASS(void);
 struct opt_pass *_MAKE_PASS_NAME_PASS(void)
 {
        return &_PASS_NAME_PASS.pass;

These were all manually built using a script running on a Debian box. 
Installing precompiled distro versions of rather old gccs would have 
been somewhat challenging. I've just rebuilt 4.6.4 to double check that 
I wasn't just seeing things, but it seems that it definitely is still 
putting c-common.h in the old location.

for reference, this is the git commit that did the move:

commit 7bedc3a05d34cd81e4835a2d3ff8c0ec7108eeb5
Author: steven <steven@138bc75d-0d04-0410-961f-82ee72b054a4>
Date:   Sat Jun 5 20:33:22 2010 +0000

    gcc/ChangeLog:
            * c-common.c: Move to c-family/.
            * c-common.def: Likewise.
            * c-common.h: Likewise.