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

[Jim Seymour <jim@cipher.com>]

Andrew Lunn wrote:
> 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.

If I'm understanding you here, it sounds like I want some way for the 
preprocessor to detect the presence of the -E option.

I'm not seeing any way to do this, though.  As far as I can see, the -E 
option behaves exactly like a normal compile - it just stops after the 
preprocessor.

I suppose a slightly less kludgy solution to my problem might be to add 
something like -DPREPROCESSOR_ONLY to the the "heapgeninc.tcl" and 
"target.ld" rules.

-- 
Jim Seymour, Cipher Systems, Inc., 503-617-7447, http://www.cipher.com

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