bors bd53aa3bf7 Auto merge of #129317 - compiler-errors:expectation-subtyping, r=lcnr ... Use equality when relating formal and expected type in arg checking #129059 uncovered an interesting issue in argument checking. When we check arguments, we create three sets of types: * Formals * Expected * Actuals The **actuals** are the types of the argument expressions themselves. The **formals** are the types from the signature that we're checking. The **expected** types are the formal types, but passed through `expected_inputs_for_expected_outputs`: a971212545/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs (L691-L725) This method attempts to constrain the formal inputs by relating the [expectation](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_hir_typeck/expectation/enum.Expectation.html) of the call expression and the formal output. When we check an argument, we get the expression's actual type, and then we first attempt to coerce it to the expected type: a971212545/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs (L280-L293) Then we subtype the expected type and the formal type: a971212545/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs (L299-L305) However, since we are now recording the right coercion target (since #129059), we now end up recording the expected type to the typeck results, rather than the actual. Since that expected type was [fudged](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_infer/infer/struct.InferCtxt.html#method.fudge_inference_if_ok), it has fresh variables. And since the expected type is only subtyped against the formal type, if that expected type has a bivariant parameter, it will likely remain unconstrained since `Covariant * Bivariant = Bivariant` according to [xform](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/enum.Variance.html#method.xform). This leads to an unconstrained type variable in writeback. AFAICT, there's no reason for us to be using subtyping here, though. The expected output is already related to the expectation by subtyping: a971212545/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs (L713) So the formals don't need "another" indirection of subtyping in the argument checking... So I've changed it to use equality here. We could alternatively fix this by requiring WF for all the expected types to constrain their bivariant parameters, but this seems a bit overkill. Fixes #129286		2024-09-02 16:08:50 +00:00
..
assembly	Revert "Auto merge of #127537 - veluca93:struct_tf, r=BoxyUwU"	2024-09-01 16:35:53 +02:00
auxiliary
codegen	Rollup merge of #129316 - dingxiangfei2009:riscv64-imac-scs, r=nnethercote	2024-08-29 16:21:47 +02:00
codegen-units
coverage
coverage-run-rustdoc
crashes	Rollup merge of #129780 - cyrgani:master, r=compiler-errors	2024-09-01 03:58:05 +02:00
debuginfo	Make option-like-enum.rs UB-free and portable	2024-08-27 19:12:14 -04:00
incremental	Rollup merge of #127279 - bvanjoi:fix-112680, r=petrochenkov	2024-08-21 19:35:10 +02:00
mir-opt	Rollup merge of #129493 - cjgillot:early-opaque-def, r=petrochenkov	2024-09-01 03:58:04 +02:00
pretty	stabilize raw_ref_op	2024-08-18 19:46:53 +02:00
run-make	Rollup merge of #129837 - aDotInTheVoid:test-better-json, r=jieyouxu	2024-09-02 04:19:30 +02:00
run-pass-valgrind
rustdoc	Rollup merge of #129560 - GuillaumeGomez:impl-assoc-type-source-link, r=notriddle	2024-08-27 00:42:01 +02:00
rustdoc-gui	Rollup merge of #127474 - tesuji:foldable-inline-derefs, r=t-rustdoc	2024-09-02 04:19:27 +02:00
rustdoc-js
rustdoc-js-std	rustdoc: show exact case-sensitive matches first	2024-08-23 13:05:24 -04:00
rustdoc-json	Rollup merge of #129123 - aDotInTheVoid:rustdoc-json-self, r=fmease	2024-08-31 10:08:52 +02:00
rustdoc-ui	Adjust expected errors for a rustdoc test	2024-08-18 22:52:54 -05:00
ui	Auto merge of #129317 - compiler-errors:expectation-subtyping, r=lcnr	2024-09-02 16:08:50 +00:00
ui-fulldeps	Deny imports of rustc_type_ir::inherent outside of type ir + new trait solver	2024-09-01 12:16:18 -04:00
COMPILER_TESTS.md