Re: symbol database for C++ compiler

"Joachim Durchholz" <joachim_d@gmx.de> wrote in message
> The MSVC++ compiler does something like this (it uses a "program
> database"). However, this is generally difficult to do in C++:
> changing a preprocessor symbol may change the syntax of large parts of
> source, making it difficult for the compiler to decide what to
> invalidate after a change. This means either more recompilation than
> strictly necessary, or a large and complex (and thus more buggy)
> dependency tracker.


By way of illustration:


I recently used MSVC++ 6.0 on a medium sized project. A
complete build took 10 minutes before the "program database" was
built, and less than 2 minutes after. Incremental builds were
almost instantaneous if only one or two object files were involved.


However, incremental changes to some of the template-based code
caused the compiler to choke reporting an internal error(!) The
workaround for this feature is a complete rebuild.


Lest I provoke an anti-MS flame war, I should also mention that I
have encountered oddly similar behaviour with template-based code
and gcc (Linux x86); under certain circumstances (which I have not
been able to fathom) making incremental changes to template code in
a project with a large number of interdependent modules causes
internal errors or mysterious symbol naming problems at link
time - even when all dependencies have apparently been rebuilt.
Again, the solution is a complete rebuild.


Regards


Jonathan

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