[cfe-dev] PCH without original files

[Argyrios Kyrtzidis]

On Jan 25, 2011, at 5:07 AM, Axel Naumann wrote:

> Hi,
> 
> Attached patch allows the ASTReader to use a PCH even if the original
> files (which are store as absolute file names or relative to sysroot)
> have been removed. Drawback: without these original files, diagnostics
> referring to source locations in the original files cannot show the
> source code:
> 
> $ cat test.h
> void f(){}
> $ cat test.cxx
> int f(){}
> $ clang -cc1 -x c++ -emit-pch test.h -o test.h.pch
> $ clang -cc1 -include-pch test.h.pch -emit-obj test.cxx
> test.cxx:1:5: error: functions that differ only in their return type
> cannot be overloaded
> int f(){}
>    ^
> /build/llvm/tmp/relopch/email/test.h:1:6: note: previous definition is here
> void f(){}
>     ^
> 1 error generated.
> $ rm test.h
> $ clang -cc1 -include-pch test.h.pch -emit-obj test.cxx
> test.cxx:1:5: error: functions that differ only in their return type
> cannot be overloaded
> int f(){}
>    ^
> 1 error generated.

Shouldn't we show the messages that occured, just not the source, e.g:

test.cxx:1:5: error: functions that differ only in their return type
cannot be overloaded
int f(){}
   ^
/build/llvm/tmp/relopch/email/test.h:1:6: note: previous definition is here
1 error generated.

This what gcc does, and I think notes are generally informative enough to show.
You also squash some warnings, e.g:

$ cat test.h
struct S {
	char x;
	int y;
};
$ cat test.cxx
void qq(S*) {}
$ clang -cc1 -x c++ -emit-pch test.h -o test.h.pch
$ clang -cc1 -include-pch test.h.pch -emit-obj test.cxx -Wpadded
/Users/argiris/proj/llvm/src/tools/clang/test.h:3:6: warning: padding struct 'S' with 3 bytes to align 'y'
        int y;
            ^
1 warning generated.
$ rm test.h
$ clang -cc1 -include-pch test.h.pch -emit-obj test.cxx -Wpadded
1 warning generated.


-Argiris

> 
> make test is happy. Please let me know whether this is okay to commit.
> 
> As a next step, I want to implement header search in the ASTReader if
> the relocatable flag is set, and if the original file cannot be found.
> 
> Cheers, Axel.
> <ASTReader_FileNotFound.diff>_______________________________________________
> cfe-dev mailing list
> cfe-dev at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev