Rollup merge of #154606 - cyrgani:misc-test-cleanups, r=Kivooeo

misc test cleanups

These are some mixed cleanups to `tests/ui` that individually seemed too small for a PR of their own. Some duplicated tests are removed, `issues-*` tests are renamed and more FIXMEs are added to `ui/README.md`.
Reasoning for the deleted tests:
* `tests/ui/associated-types/issue-47814.rs`: duplicate of `tests/ui/associated-consts/issue-47814.rs`
* rename `tests/ui/closures/2229_closure_analysis/migrations/issue-78720.rs` to `.../nested-copy-drops-83176.rs` since rust-lang/rust#78720 was not the correct issue, rust-lang/rust#83176 was.
* `tests/ui/specialization/defaultimpl/specialization-feature-gate-default.rs`: duplicate of `tests/ui/specialization/specialization-feature-gate-default.rs`
* `fn/issue-1900.rs`: duplicate of `error-codes/E0131.rs`

r? @Kivooeo

src/tools/tidy/src/issues.txt

@@ -117,7 +117,6 @@ ui/associated-types/issue-44153.rs
 ui/associated-types/issue-47139-1.rs
 ui/associated-types/issue-47139-2.rs
 ui/associated-types/issue-47385.rs
-ui/associated-types/issue-47814.rs
 ui/associated-types/issue-48010.rs
 ui/associated-types/issue-48551.rs
 ui/associated-types/issue-50301.rs
@@ -406,7 +405,6 @@ ui/closures/2229_closure_analysis/match/issue-87097.rs
 ui/closures/2229_closure_analysis/match/issue-87426.rs
 ui/closures/2229_closure_analysis/match/issue-87988.rs
 ui/closures/2229_closure_analysis/match/issue-88331.rs
-ui/closures/2229_closure_analysis/migrations/issue-78720.rs
 ui/closures/2229_closure_analysis/migrations/issue-86753.rs
 ui/closures/2229_closure_analysis/migrations/issue-90024-adt-correct-subst.rs
 ui/closures/2229_closure_analysis/run_pass/issue-87378.rs
@@ -1001,7 +999,6 @@ ui/fmt/issue-86085.rs
 ui/fmt/issue-89173.rs
 ui/fmt/issue-91556.rs
 ui/fn/issue-1451.rs
-ui/fn/issue-1900.rs
 ui/fn/issue-3044.rs
 ui/fn/issue-3099.rs
 ui/fn/issue-3904.rs

tests/ui/README.md

@@ -36,6 +36,8 @@ These tests exercise the [`annotate-snippets`]-based emitter implementation.
 
 [`annotate-snippets`]: https://github.com/rust-lang/annotate-snippets-rs
 
+**FIXME**: merge this with `error-emitter`
+
 ## `tests/ui/anon-params`
 
 These tests deal with anonymous parameters (no name, only type), a deprecated feature that becomes a hard error in Edition 2018.
@@ -141,6 +143,8 @@ However, only a single test was ever added to this category: <https://github.com
 
 Tests for pattern binding in match expressions, let statements, and other binding contexts. E.g. binding modes and refutability. See [Patterns | Reference](https://doc.rust-lang.org/reference/patterns.html).
 
+**FIXME**: quite some overlap with `tests/ui/pattern` and `tests/ui/match`.
+
 ## `tests/ui/binop/`: Binary operators
 
 Tests for binary operators (such as `==`, `&&` or `^`). E.g. overloading, type checking, and diagnostics for invalid operations.
@@ -272,7 +276,7 @@ This directory is actually for the standard library [`std::process::Command`](ht
 
 Some traits' implementation must be compared with their definition, checking for problems such as the implementation having stricter requirements (such as needing to implement `Copy`).
 
-This subdirectory is *not* intended comparison traits (`PartialEq`, `Eq`, `PartialOrd`, `Ord`).
+This subdirectory is *not* intended for comparison traits (`PartialEq`, `Eq`, `PartialOrd`, `Ord`).
 
 ## `tests/ui/compile-flags/`
 
@@ -448,6 +452,8 @@ Exercises diagnostics for when a code block attempts to gain ownership of a non-
 
 Exercises diagnostics for disallowed struct destructuring.
 
+**FIXME**: does this really need to be its own immediate subdirectory?
+
 ## `tests/ui/dist`
 
 Tests that require distribution artifacts.
@@ -508,7 +514,7 @@ These tests run in specific Rust editions, such as Rust 2015 or Rust 2018, and c
 
 ## `tests/ui/eii`: Externally Implementable Items
 
-Exercises `eii` keyword.
+Exercises the `#[eii]` attribute and related features.
 
 ## `tests/ui/entry-point/`: `main` function
 
@@ -611,8 +617,6 @@ Tests for `#![feature(fn_traits)]`. See [`fn_traits` | The Unstable book](https:
 
 Anything to do with loops and `for`, `loop` and `while` keywords to express them.
 
-**FIXME**: After `ui/for` is merged into this, also carry over its SUMMARY text.
-
 ## `tests/ui/force-inlining/`: `#[rustc_force_inline]`
 
 Tests for `#[rustc_force_inline]`, which will force a function to always be labelled as inline by the compiler (it will be inserted at the point of its call instead of being used as a normal function call.) If the compiler is unable to inline the function, an error will be reported. See <https://github.com/rust-lang/rust/pull/134082>.
@@ -730,6 +734,8 @@ Tests on type inference.
 
 Tests for diagnostics on infinitely recursive types without indirection.
 
+**FIXME**: check for overlap with `structs-enums/enum-rec` and `structs-enums/struct-rec`
+
 ## `tests/ui/inline-const/`
 
 These tests revolve around the inline `const` block that forces the compiler to const-eval its content.
@@ -853,7 +859,9 @@ Tests exercising analysis for unused variables, unreachable statements, function
 
 ## `tests/ui/loop-match`
 
-Tests for `loop` with `match` expressions.
+Tests for the `loop_match` feature to optimize `loop`s consisting of one big `match` expressions.
+
+See [Tracking issue for way to express intraprocedural finite state machines #132306](https://github.com/rust-lang/rust/issues/132306).
 
 ## `tests/ui/loops/`
 
@@ -891,6 +899,8 @@ See [Tracking issue for allowing overlapping implementations for marker trait #2
 
 Broad category of tests on `match` constructs.
 
+**FIXME**: many tests overlap with `tests/ui/bindings`, try to reduce duplication.
+
 ## `tests/ui/methods/`
 
 A broad category for anything related to methods and method resolution.
@@ -899,6 +909,8 @@ A broad category for anything related to methods and method resolution.
 
 Certain mir-opt regression tests.
 
+**FIXME**: many tests in this directory are not about MIR or optimizations, relocate these.
+
 ## `tests/ui/mir-dataflow`
 
 Tests for MIR dataflow analysis.
@@ -977,6 +989,8 @@ Tests that exercises edge cases, such as specific floats, large or very small nu
 
 Tests that checks numeric types and their interactions, such as casting among them with `as` or providing the wrong numeric suffix.
 
+**FIXME**: these tests could get moved to other directories, in particular `cast/` or `parser/`.
+
 ## `tests/ui/object-lifetime/`
 
 Tests on lifetimes on objects, such as a lifetime bound not being able to be deduced from context, or checking that lifetimes are inherited properly.
@@ -1308,7 +1322,7 @@ Some standard library tests which are too inconvenient or annoying to implement
 
 ## `tests/ui/str/`
 
-Exercise `str` keyword and string slices.
+Exercise `str` primitive and string slices.
 
 ## `tests/ui/structs/`
 
@@ -1464,6 +1478,8 @@ See [RFC 0132 Unified Function Call Syntax](https://github.com/rust-lang/rfcs/bl
 
 `#![feature(unboxed_closures)]`, `Fn`, `FnMut` and `FnOnce` traits
 
+**FIXME**: many tests have `unboxed-closure` in their name but only test normal closures, rename these.
+
 See [Tracking issue for Fn traits (`unboxed_closures` & `fn_traits` feature)](https://github.com/rust-lang/rust/issues/29625).
 
 ## `tests/ui/underscore-lifetime/`: `'_` elided lifetime

tests/ui/associated-types/issue-47814.rs

@@ -1,13 +0,0 @@
-struct ArpIPv4<'a> {
-    s: &'a u8
-}
-
-impl<'a> ArpIPv4<'a> {
-    const LENGTH: usize = 20;
-
-    pub fn to_buffer() -> [u8; Self::LENGTH] { //~ ERROR generic `Self` types are currently not permitted in anonymous constants
-        unimplemented!()
-    }
-}
-
-pub fn main() {}

tests/ui/associated-types/issue-47814.stderr

@@ -1,14 +0,0 @@
-error: generic `Self` types are currently not permitted in anonymous constants
-  --> $DIR/issue-47814.rs:8:32
-   |
-LL |     pub fn to_buffer() -> [u8; Self::LENGTH] {
-   |                                ^^^^
-   |
-note: not a concrete type
-  --> $DIR/issue-47814.rs:5:10
-   |
-LL | impl<'a> ArpIPv4<'a> {
-   |          ^^^^^^^^^^^
-
-error: aborting due to 1 previous error
-

tests/ui/closures/2229_closure_analysis/migrations/nested-copy-drops-83176.rs

@@ -1,3 +1,4 @@
+// Regression test for https://github.com/rust-lang/rust/issues/83176.
 //@ run-pass
 
 #![warn(rust_2021_incompatible_closure_captures)]

tests/ui/closures/2229_closure_analysis/migrations/nested-copy-drops-83176.stderr

@@ -1,5 +1,5 @@
 warning: irrefutable `if let` pattern
-  --> $DIR/issue-78720.rs:7:8
+  --> $DIR/nested-copy-drops-83176.rs:8:8
    |
 LL |     if let a = "" {
    |        ^^^^^^^^^^

tests/ui/fn/issue-1900.rs

@@ -1,2 +0,0 @@
-fn main<T>() { }
-//~^ ERROR `main` function is not allowed to have generic parameters

tests/ui/fn/issue-1900.stderr

@@ -1,9 +0,0 @@
-error[E0131]: `main` function is not allowed to have generic parameters
-  --> $DIR/issue-1900.rs:1:8
-   |
-LL | fn main<T>() { }
-   |        ^^^ `main` cannot have generic parameters
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0131`.

tests/ui/impl-trait/rpit/unit-impl-default-36379.rs

@@ -0,0 +1,6 @@
+//! Regression test for https://github.com/rust-lang/rust/issues/36379
+//@ check-pass
+
+fn _test() -> impl Default { }
+
+fn main() {}

tests/ui/issues/issue-36379.rs

@@ -1,5 +0,0 @@
-//@ check-pass
-
-fn _test() -> impl Default { }
-
-fn main() {}

tests/ui/specialization/defaultimpl/specialization-feature-gate-default.rs

@@ -1,11 +0,0 @@
-// Check that specialization must be ungated to use the `default` keyword
-
-trait Foo {
-    fn foo(&self);
-}
-
-default impl<T> Foo for T { //~ ERROR specialization is unstable
-    fn foo(&self) {}
-}
-
-fn main() {}

tests/ui/specialization/defaultimpl/specialization-feature-gate-default.stderr

@@ -1,15 +0,0 @@
-error[E0658]: specialization is unstable
-  --> $DIR/specialization-feature-gate-default.rs:7:1
-   |
-LL | / default impl<T> Foo for T {
-LL | |     fn foo(&self) {}
-LL | | }
-   | |_^
-   |
-   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
-   = help: add `#![feature(specialization)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0658`.