replace-dependent-typedef breaks on typedef in template struct

[emaxx-google]

The following error is generated:

pass_clang::replace-dependent-typedef has encountered a bug:
pass failed to modify the variant

when the input is:

template <typename T>
struct A {
  struct Inner;
  typedef A::Inner Bar;
};

[emaxx-google]

It seems that the problem is this check that gets misled by different string representations: A<T>::Inner vs. A::Inner:

creduce/clang_delta/ReplaceDependentTypedef.cpp

Line 148 in 31e855e

if (Str == TdefTyStr)

[emaxx-google]

Some possible directions:

• A: Do string comparison of the original text and the replacement - and exit with an error if it's the same.
  • => very simple to implement, but feels a bit wasteful (2 applications of the pass in the same location might be required before the idempotence gets discovered).
• B: Skip applying the pass to typedefs that don't actually refer, directly or indirectly, to another typedef.
  • => this corresponds better to the idea behind the pass (the word "dependent" in the pass' name), but might be a bit more fragile to implement.
• ...?

[eeide]

Thank you for your bug report!

[emaxx-google]

I'm happy to propose a PR as a starting point. (And probably basic unit tests for this pass.)