[cfe-dev] Feature proposal: Compile Configuration Disclosure

[James Widman]

On Mar 3, 2010, at 9:20 PM, James Widman wrote:

> On Mar 3, 2010, at 7:05 PM, Douglas Gregor wrote:
> 
>> 
>> On Mar 3, 2010, at 2:44 PM, James Widman wrote:
>> 
>>>  - The path name of the primary source file;
>>> 
>>>  - The working directory;
>>> 
>>>  - Environment variables;
>> 
>> How would these affect translation ???
> 
> Well, some compilers depend on environment variables.


Ack; forgot the other two bullets.  

 - The path name of the primary source file

Ho else would we know which .cpp file to parse?

Also, note that pre-defined macros, the #include search path (and generally, details about how the compiler is invoked) can vary from TU to TU.  So in:

  clang --disclose-config -DBAR -c x.cpp -o foo.o

... the file foo.o.config-disclosure would reveal not just that clang was once invoked with a predefined "#define BAR 1", but that this invocation was used on x.cpp.  Now, when a tool processes x.cpp, it's guaranteed to start with the same set of predefined macros that clang started with.  The set---er, sorry; the *sequence* of predefined macros may differ for y.cpp.

 - The working directory

You could easily have more than one "x.cpp" in a directory tree.  One might then suggest that x.cpp's full pathname be output instead.  And that's fine, but:

   - it could have an effect on how x.cpp is cited in diagnostics.

   - in the process of forming the full pathname, you first have to get the working directory anyway.

Also,-I options typically include things like -I. and -I../asdf.

James Widman  
-- 
Gimpel Software 
http://gimpel.com