Don't probe InferConst in fold_const if self.infcx is None, deeply_normalize tys in check_tys_might_be_eq

[ShE3py]

Fixes #119381, fixes #114456.

[rustbot]

r? @TaKO8Ki

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[rustbot]

changes to the core type system

cc @compiler-errors, @lcnr

[compiler-errors]

r? lcnr

[rustbot]

Some changes occurred in src/tools/compiletest

cc @jieyouxu

[ShE3py]

@rustbot label -A-testsuite -T-bootstrap
(typo fix)

[BoxyUwU]

Im not sure this fix is correct. Whether the paramenv has already been canonicalized or not has nothing to do with whether we can encounter consts with aliases as their type.

I would expect the correct fix to be to normalize both types in check_tys_might_be_eq . We probably have to be careful there with errors during normalization because if we're in a probe and have an non wf alias which doesn't cause an error then we don't want to ICE in this check.

Sooo we probably want that fn to call deeply_nornalize then select_all_or_error, but return Ok(()) in case of error. Though at this point this check is becoming a bit of a pain lol...

[ShE3py]

Ty for the pointers, though non-wf aliases ICEs even without deeply_nornalizeing the tys;

struct Sized<T>(T);
type NonWf = Sized<dyn ToString>;

struct Walk<const W: NonWf> {}
impl Walk<{ Sized("") }> {}

https://play.rust-lang.org/?gist=66eb4c5f0a126c73ba8734ef399b639d

@rustbot label -A-testsuite -T-bootstrap

[BoxyUwU]

Why the first commit? You didn't update the function that handles tys and also it shouldn't be required for this as in super_combine_tys we have an infcx available for canonicalization

[ShE3py]

It's for #119381, whose backtrack is as follow:

0. Canonicalizer::fold_const where self.infcx.unwrap() fails
1. InferCtxt::canonicalize_query::{closure#0} where infcx := None
2. CanonicalParamEnvCache::get_or_insert whose docstring says that it shouldn't resolve inference variables as to not invalidates its cache (PR cache param env canonicalization #117749)
3. InferCtxt::canonicalize_query
4. InferCtxt::super_combine_consts
5. InferCtxt::super_combine_tys

Though it may be preferable to (re-)canonicalize ParamEnv (bypassing the cache) in super_combine_consts as to have an infcx?