Feature request: Globalize symbol

[Fredrik Hugosson <fredrik dot hugosson at axis dot com>]

Hi!

When working with unit tests I frequently have the need to override a 
function or variable in a shared library. This works just as I want for 
global symbols, but if the symbol is local (declared static) I have to 
modify the source (remove the static using a STATIC preprocessor define) 
to make it work.

The setup is as follows:
app/Makefile
app/src.c
app/checktests/Makefile
app/checktests/tests.c

In the application Makefile I have a target to compile the application 
as a shared library. This target is invoked from the checktests Makefile 
and the lib is then linked with the tests. So I compile the application 
source under test from scratch and can control the flags. (To mess even 
less with the application under test I may change the setup in the 
future to include the application Makefile in a wrapper Makefile instead 
of adding a shared library target to it.)

All this makes it possible to override any global symbols in src.c by 
defining the symbol in the tests.c file. What I miss is the possibility 
to override local symbols in a similar manner, without touching the 
source. This problem could be fixed by adding some options to gcc to 
globalize symbols.


My proposal is the following new options:
-fglobalize-symbol=SYMBOLNAME
-fglobalize-symbols=FILENAME
-fglobalize-all-symbols

The first option makes the symbol SYMBOLNAME global.
The second option makes all symbols in FILENAME global.
The third option makes all symbols global.

The globalization should apply to all symbols that are visible on the 
file scope level but not globally visible. E.g. both functions declared 
'static' and variables declared 'static' (outside functions). The 
attribute '__attribute__ ((hidden))' may be overridden too, but for my 
purposes I don't have the need for this.


Waiting hopefully
/HUGO.