While debugging a self comparison error, I realized that some types
where comparing different during IR type canonicalization for no good
reason. Looking deeper, I realized it's due to an anonymous enum
comparing different to the same anonymous enum defined elsewhere.
Both anonymous enums have naming typedefs. The discrepancy is due to
the fact that one of these enums didn't have its naming typedef
applied, by the DWARF reader. This is because the DWARF reader
"re-uses" typedef types whenever it can, and thus re-uses naming
typedefs too. Thinking deeply about this, I think naming typedefs
should not be re-used, otherwise, some anonymous types would lack
their naming typedefs. Oops.
So the patch avoids typedefs to be re-used altogether. There doesn't
seem to be any performance hit.
With that fixed, another problem came up: Some typedefs of type foo
are compared to said type foo and the comparison yields "false",
wrongly. This is in the context of a type 'foo' used by type 'bar'
defined in a translation unit, and the same type 'bar' uses a typedef
of 'foo' in another translation unit. Both types 'bar' should compare
equal, but don't, today. This is true especially for function types.
The patch strips typedefs off of the types of function parameters when
comparing function types. To make things consistent, typedefs are
stripped off of function parameters when function types (and decls)
are pretty printed for internal purposes, especially for type
canonicalization.
git://sourceware.org / libabigail.git / commit