[Bug c++/70594] [6 Regression] -fcompare-debug failure

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70594

--- Comment #4 from Tobias Burnus <burnus at gcc dot gnu.org> ---
Created attachment 38225
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38225&action=edit
test.ii  test case (g++ -O1 -fcompare-debug)

(In reply to Jakub Jelinek from comment #1)
> Without the testcase it is hard to guess.

I now tried to compile LLVM with -fcompare-debug - and I guessed correctly, one
of the files also fails there (lib/Support/CommandLine.cpp).

I am not sure whether it is the same issue, but it is a debug miscompare.
Contrary to my original file, it also fails when a .ii is generated with "-E";
additionally, it also fails already with -O1 and it reduced more readily (for
my original example, it seemed to depend much more on the memory layout such
that comment lines were kept).

The somewhat reduced example is attached; it fails here (and hopefully
elsewhere) using "g++ -O1 -fcompare-debug" with: "g++: error: test.ii:
-fcompare-debug failure".