[ECOS] -isystem and 'Template with C Linkage'

[John Carter]

I have the answer now, so this is just for the next poor sod who gets
bitten by this fairly unlikely scenario...

So I wanted to extend "kapi.h" under ecos-2.0.

I wrote my .h I wrote my .cxx and pulled in "thread.hxx" to access
a certain C++ only method on threads. (stack_check)

Compiled and gcc spits a warning "Template with C linkage" in clist.hxx

Wah!? After a days worth of Googling and deep forensics of the
preprocessor output (Did you know the...
      # LINENUM FILENAME FLAGS
... linemarkers encode the C linkage in the FLAGS field?

Anyhoo, after a days worth of hunting inappropriate 'extern "C" {}'
behaviour I stumble on this brief paragraph in the info docs...

    "On very old systems, some of the pre-defined system header
     directories get even more special treatment.  GNU C++ considers
     code in headers found in those directories to be surrounded by an
     `extern "C"' block.  There is no way to request this behavior with
     a `#pragma', or from the command line."

Oh dear, the build system I'm using marks the ecos <cyg/kernel/...>
paths as -isystem. Stop doing that and use -I paths to the ecos stuff
and the problem went away.

Sigh! A wasted day.




John Carter                             Phone : (64)(3) 358 6639
Tait Electronics                        Fax   : (64)(3) 359 4632
PO Box 1645 Christchurch                Email : john.carter@tait.co.nz
New Zealand


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