Re: [ECOS] CDL define_proc: Unable to put "extern" in an include files

[Andrew Lunn <andrew at lunn dot ch>]

On Wed, May 30, 2007 at 10:58:29AM -0700, Jim Seymour wrote:
> I have a desire to inject an "extern" statement into an include file
> generated by one of our CDL files - so I added a "define_proc" block.
> 
> Worked like a champ - until the build got to the rule to create
> "heapgeninc.tcl" out of heapgen.cpp.
> 
> This file is run through the preprocessor and the output is then fed to
> Tcl.  My "extern" statement is passed through the preprocessor intact,
> so when it gets to Tcl, I get this error:
> 
>    invalid command name "extern"
> 
> The same problem exists when the target.ld file is built.  My "extern"
> statement gets stuffed into that file, so ld fails with a "parse error".
> 
> I fixed both problems with a horrible kludge: adding a #define to
> heapgen.cpp and then bracketing my extern with a #ifndef. 

Could you turn this around. I think cpp is used to generate the linker
file, heapgeninc.tcl and it is used when compiling C and C++
code. However each invocation is for different languages.

Take a  look at the output of:

gcc -v -E -dD empty.c
gcc -v -E -dD empty.cpp

and see if there is something defined when compiling real code which
is not defined when using CPP for building the .ld file etc. Then use
#ifdef so that the extern is only present for real code generation
compilation.

        Andrew

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