delegation: remove method call generation

[aerooneqq]

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This PR removes method call generation from delegations, now we always generate default call. Part of #118212.

We reuse methods probing engine for finding needed adjustments, thus extending number of supported cases. In this PR adjustments are applied to trait methods (was supported before) and static functions (new feature). Free functions can be supported later.

Finally this PR solves issues from parent generics propagation from #155906.

r? @petrochenkov

[petrochenkov]

Example of static trait functions reuses that are now working:

Is there specific motivation for this? I wouldn't expect this to work.

I actually think we need to change the design to ignore the target expression entirely if there's no self parameter.
In that case both static and non-static methods will be able to be delegated together.

reuseTrait::{method, static_fn}{self.field}

=>

fnmethod(&self,a:A,b:B){self.field.method(a, b)// behavior, not exact desugaring}fnstatic_fn(a:A,b:B){Trait::static_fn(a, b)// no self, so the target expr is ignored}

[petrochenkov]

ignore the target expression entirely if there's no self parameter

Or rather generate something like

fnstatic_fn(a:A,b:B){
target_expr;// usually dead code and noopTrait::static_fn(a, b)// no self, so the target expr is ignored}

to avoid issues like #154363 (comment).

[aerooneqq]

@rustbot ready

[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[petrochenkov]

Let's run benchmarks, get_scope_for_method_call_adjustments now accesses some HIR on a good path for all calls, which may potentially cause issues in incremental mode.
@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: 507e776 (507e776eb6c7dbce11a65799367ea71749babf4c, parent: 6083f7891b5088184968e050d0eaecc7bcfd2b3d)

[aerooneqq]

@rustbot ready

[petrochenkov]

@bors r+

[rust-bors]

📌 Commit 40a7821 has been approved by petrochenkov

It is now in the queue for this repository.

[rust-bors]

💔 Test for 9db232a failed: CI. Failed job:

• auto - x86_64-gnu-llvm-21-3 (web logs, enhanced plaintext logs)

[rust-log-analyzer]

A job failed! Check out the build log: (web)(plain enhanced)(plain)

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[JonathanBrouwer]

@bors retry