Make PlaceholderReplacer shallow_resolver and recur when infer vars

[spastorino]

This makes resolve type and const infer vars resolve.

Given:

#![feature(inherent_associated_types)]
#![allow(incomplete_features)]

struct Foo<T>(T);

impl<'a> Foo<fn(&'a ())> {
    type Assoc = &'a ();
}

fn bar(_: for<'a> fn(Foo<fn(Foo<fn(&'static ())>::Assoc)>::Assoc)) {}

fn main() {}

We should normalize for<'a> fn(Foo<fn(Foo<fn(&'static ())>::Assoc)>::Assoc) to for<'0> fn(&'1 ()) with '1 == '0 and '0 == 'static constraints. We have to resolve '1 to 'static in the infcx associated to PlaceholderReplacer.

This is part of #118118 but unrelated to that PR.

r? @compiler-errors @lcnr

[compiler-errors]

r=me with perf run

[spastorino]

@bors try @rust-timer queue

[bors]

⌛ Trying commit f57e184 with merge 5567761...

[bors]

☀️ Try build successful - checks-actions
Build commit: 5567761 (5567761f5b540b701b717b47271aadf924861f81)

[rust-timer]

Finished benchmarking commit (5567761): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	4.1%	[4.1%, 4.1%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.1%	[-1.1%, -1.1%]	1
Improvements ✅ (secondary)	-1.8%	[-2.8%, -0.8%]	2
All ❌✅ (primary)	1.5%	[-1.1%, 4.1%]	2

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 676.964s -> 673.318s (-0.54%)
Artifact size: 313.51 MiB -> 313.49 MiB (-0.01%)

[spastorino]

@bors r=compiler-errors

[bors]

📌 Commit f57e184 has been approved by compiler-errors

It is now in the queue for this repository.

[bors]

⌛ Testing commit f57e184 with merge b2e73e9...

[bors]

☀️ Test successful - checks-actions
Approved by: compiler-errors
Pushing b2e73e9 to master...

[rust-timer]

Finished benchmarking commit (b2e73e9): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.5%	[-3.9%, -1.1%]	4
All ❌✅ (primary)	-	-	0

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.2%	[-2.4%, -2.0%]	4
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 673.904s -> 673.908s (0.00%)
Artifact size: 313.23 MiB -> 313.32 MiB (0.03%)