Rollup merge of #138898 - fmease:decrustify-parser-post-ty-ascr, r=compiler-errors

Mostly parser: Eliminate code that's been dead / semi-dead since the removal of type ascription syntax

**Disclaimer**: This PR is intended to mostly clean up code as opposed to bringing about behavioral changes. Therefore it doesn't aim to address any of the 'FIXME: remove after a month [dated: 2023-05-02]: "type ascription syntax has been removed, see issue [#]101728"'.

---

By commit:

1. Removes truly dead code:
   * Since 1.71 (#109128) `let _ = { f: x };` is a syntax error as opposed to a semantic error which allows the parse-time diagnostic (suggestion) "*struct literal body without path // you might have forgotten […]*" to kick in.
   * The analysis-time diagnostic (suggestion) from <=1.70 "*cannot find value \`f\` in this scope // you might have forgotten […]*" is therefore no longer reachable.
2. Updates `is_certainly_not_a_block` to be in line with the current grammar:
   * The seq. `{ ident:` is definitely not the start of a block. Before the removal of ty ascr, `{ ident: ty_start` would begin a block expr.
   * This shouldn't make more code compile IINM, it should *ultimately* only affect diagnostics.
   * For example, `if T { f: () } {}` will now be interpreted as an `if` with struct lit `T { f: () }` as its *condition* (which is banned in the parser anyway) as opposed to just `T` (with the *consequent* being `f : ()` which is also invalid (since 1.71)). The diagnostics are almost the same because we have two separate parse recovery procedures + diagnostics: `StructLiteralNeedingParens` (*invalid struct lit*) before and `StructLiteralNotAllowedHere` (*struct lits aren't allowed here*) now, as you can see from the diff.
   * (As an aside, even before this PR, fn `maybe_suggest_struct_literal` should've just used the much older & clearer `StructLiteralNotAllowedHere`)
   * NB: This does sadly regress the compiler output for `tests/ui/parser/type-ascription-in-pattern.rs` but that can be fixed in follow-up PRs. It's not super important IMO and a natural consequence.
3. Removes code that's become dead due to the prior commit.
   * Basically reverts #106620 + #112475 (without regressing rustc's output!).
   * Now the older & more robust parse recovery procedure (cc `StructLiteralNotAllowedHere`) takes care of the cases the removed code used to handle.
   * This automatically fixes the suggestions for \[[playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=7e2030163b11ee96d17adc3325b01780)\]:
     * `if Ty::<i32> { f: K }.m() {}`: `if Ty::<i32> { SomeStruct { f: K } }.m() {}` (broken) → ` if (Ty::<i32> { f: K }).m() {}`
     * `if <T as Trait>::Out { f: K::<> }.m() {}`: `if <T as Trait>(::Out { f: K::<> }).m() {}` (broken) → `if (<T as Trait>::Out { f: K::<> }).m() {}`
4. Merge and simplify UI tests pertaining to this issue, so it's easier to add more regression tests like for the two cases mentioned above.
5. Merge UI tests and add the two regression tests.

Best reviewed commit by commit (on request I'll partially squash after approval).

20 files changed, 388 insertions, 477 deletions

diff --git a/tests/ui/parser/issues/issue-111692.rs b/tests/ui/parser/issues/issue-111692.rs
deleted file mode 100644
index 56096f706a8..00000000000
--- a/tests/ui/parser/issues/issue-111692.rs
+++ /dev/null
@@ -1,32 +0,0 @@
-mod module {
-    #[derive(Eq, PartialEq)]
-    pub struct Type {
-        pub x: u8,
-        pub y: u8,
-    }
-
-    pub const C: u8 = 32u8;
-}
-
-fn test(x: module::Type) {
-    if x == module::Type { x: module::C, y: 1 } { //~ ERROR invalid struct literal
-    }
-}
-
-fn test2(x: module::Type) {
-    if x ==module::Type { x: module::C, y: 1 } { //~ ERROR invalid struct literal
-    }
-}
-
-
-fn test3(x: module::Type) {
-    if x == Type { x: module::C, y: 1 } { //~ ERROR invalid struct literal
-    }
-}
-
-fn test4(x: module::Type) {
-    if x == demo_module::Type { x: module::C, y: 1 } { //~ ERROR invalid struct literal
-    }
-}
-
-fn main() { }
diff --git a/tests/ui/parser/issues/issue-111692.stderr b/tests/ui/parser/issues/issue-111692.stderr
deleted file mode 100644
index 068b0483b0f..00000000000
--- a/tests/ui/parser/issues/issue-111692.stderr
+++ /dev/null
@@ -1,46 +0,0 @@
-error: invalid struct literal
-  --> $DIR/issue-111692.rs:12:21
-   |
-LL |     if x == module::Type { x: module::C, y: 1 } {
-   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: you might need to surround the struct literal with parentheses
-   |
-LL |     if x == (module::Type { x: module::C, y: 1 }) {
-   |             +                                   +
-
-error: invalid struct literal
-  --> $DIR/issue-111692.rs:17:20
-   |
-LL |     if x ==module::Type { x: module::C, y: 1 } {
-   |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: you might need to surround the struct literal with parentheses
-   |
-LL |     if x ==(module::Type { x: module::C, y: 1 }) {
-   |            +                                   +
-
-error: invalid struct literal
-  --> $DIR/issue-111692.rs:23:13
-   |
-LL |     if x == Type { x: module::C, y: 1 } {
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: you might need to surround the struct literal with parentheses
-   |
-LL |     if x == (Type { x: module::C, y: 1 }) {
-   |             +                           +
-
-error: invalid struct literal
-  --> $DIR/issue-111692.rs:28:26
-   |
-LL |     if x == demo_module::Type { x: module::C, y: 1 } {
-   |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: you might need to surround the struct literal with parentheses
-   |
-LL |     if x == (demo_module::Type { x: module::C, y: 1 }) {
-   |             +                                        +
-
-error: aborting due to 4 previous errors
-
diff --git a/tests/ui/parser/method-call-on-struct-literal-in-if-condition.rs b/tests/ui/parser/method-call-on-struct-literal-in-if-condition.rs
deleted file mode 100644
index 8be7c9ee8ac..00000000000
--- a/tests/ui/parser/method-call-on-struct-literal-in-if-condition.rs
+++ /dev/null
@@ -1,13 +0,0 @@
-pub struct Example { a: i32 }
-
-impl Example {
-    fn is_pos(&self) -> bool { self.a > 0 }
-}
-
-fn one() -> i32 { 1 }
-
-fn main() {
-    if Example { a: one(), }.is_pos() { //~ ERROR invalid struct literal
-        println!("Positive!");
-    }
-}
diff --git a/tests/ui/parser/method-call-on-struct-literal-in-if-condition.stderr b/tests/ui/parser/method-call-on-struct-literal-in-if-condition.stderr
deleted file mode 100644
index f7822ba1124..00000000000
--- a/tests/ui/parser/method-call-on-struct-literal-in-if-condition.stderr
+++ /dev/null
@@ -1,13 +0,0 @@
-error: invalid struct literal
-  --> $DIR/method-call-on-struct-literal-in-if-condition.rs:10:8
-   |
-LL |     if Example { a: one(), }.is_pos() {
-   |        ^^^^^^^^^^^^^^^^^^^^^
-   |
-help: you might need to surround the struct literal with parentheses
-   |
-LL |     if (Example { a: one(), }).is_pos() {
-   |        +                     +
-
-error: aborting due to 1 previous error
-
diff --git a/tests/ui/parser/struct-literal-in-for.rs b/tests/ui/parser/struct-literal-in-for.rs
deleted file mode 100644
index 3227ae37bfd..00000000000
--- a/tests/ui/parser/struct-literal-in-for.rs
+++ /dev/null
@@ -1,17 +0,0 @@
-struct Foo {
-    x: isize,
-}
-
-impl Foo {
-    fn hi(&self) -> bool {
-        true
-    }
-}
-
-fn main() {
-    for x in Foo { //~ ERROR struct literals are not allowed here
-        x: 3       //~^ ERROR `bool` is not an iterator
-    }.hi() {
-        println!("yo");
-    }
-}
diff --git a/tests/ui/parser/struct-literal-in-for.stderr b/tests/ui/parser/struct-literal-in-for.stderr
deleted file mode 100644
index 1c91eba68e3..00000000000
--- a/tests/ui/parser/struct-literal-in-for.stderr
+++ /dev/null
@@ -1,31 +0,0 @@
-error: struct literals are not allowed here
-  --> $DIR/struct-literal-in-for.rs:12:14
-   |
-LL |       for x in Foo {
-   |  ______________^
-LL | |         x: 3
-LL | |     }.hi() {
-   | |_____^
-   |
-help: surround the struct literal with parentheses
-   |
-LL ~     for x in (Foo {
-LL |         x: 3
-LL ~     }).hi() {
-   |
-
-error[E0277]: `bool` is not an iterator
-  --> $DIR/struct-literal-in-for.rs:12:14
-   |
-LL |       for x in Foo {
-   |  ______________^
-LL | |         x: 3
-LL | |     }.hi() {
-   | |__________^ `bool` is not an iterator
-   |
-   = help: the trait `Iterator` is not implemented for `bool`
-   = note: required for `bool` to implement `IntoIterator`
-
-error: aborting due to 2 previous errors
-
-For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/parser/struct-literal-in-if.rs b/tests/ui/parser/struct-literal-in-if.rs
deleted file mode 100644
index c4a253c3da2..00000000000
--- a/tests/ui/parser/struct-literal-in-if.rs
+++ /dev/null
@@ -1,22 +0,0 @@
-struct Foo {
-    x: isize,
-}
-
-impl Foo {
-    fn hi(&self) -> bool {
-        true
-    }
-}
-
-fn main() {
-    if Foo { //~ ERROR struct literals are not allowed here
-        x: 3
-    }.hi() {
-        println!("yo");
-    }
-    if let true = Foo { //~ ERROR struct literals are not allowed here
-        x: 3
-    }.hi() {
-        println!("yo");
-    }
-}
diff --git a/tests/ui/parser/struct-literal-in-if.stderr b/tests/ui/parser/struct-literal-in-if.stderr
deleted file mode 100644
index 8b72469fcf5..00000000000
--- a/tests/ui/parser/struct-literal-in-if.stderr
+++ /dev/null
@@ -1,34 +0,0 @@
-error: struct literals are not allowed here
-  --> $DIR/struct-literal-in-if.rs:12:8
-   |
-LL |       if Foo {
-   |  ________^
-LL | |         x: 3
-LL | |     }.hi() {
-   | |_____^
-   |
-help: surround the struct literal with parentheses
-   |
-LL ~     if (Foo {
-LL |         x: 3
-LL ~     }).hi() {
-   |
-
-error: struct literals are not allowed here
-  --> $DIR/struct-literal-in-if.rs:17:19
-   |
-LL |       if let true = Foo {
-   |  ___________________^
-LL | |         x: 3
-LL | |     }.hi() {
-   | |_____^
-   |
-help: surround the struct literal with parentheses
-   |
-LL ~     if let true = (Foo {
-LL |         x: 3
-LL ~     }).hi() {
-   |
-
-error: aborting due to 2 previous errors
-
diff --git a/tests/ui/parser/struct-literal-in-match-discriminant.rs b/tests/ui/parser/struct-literal-in-match-discriminant.rs
deleted file mode 100644
index ce132df5a88..00000000000
--- a/tests/ui/parser/struct-literal-in-match-discriminant.rs
+++ /dev/null
@@ -1,13 +0,0 @@
-struct Foo {
-    x: isize,
-}
-
-fn main() {
-    match Foo { //~ ERROR struct literals are not allowed here
-        x: 3
-    } {
-        Foo {
-            x: x
-        } => {}
-    }
-}
diff --git a/tests/ui/parser/struct-literal-in-match-discriminant.stderr b/tests/ui/parser/struct-literal-in-match-discriminant.stderr
deleted file mode 100644
index 5177f5f126e..00000000000
--- a/tests/ui/parser/struct-literal-in-match-discriminant.stderr
+++ /dev/null
@@ -1,18 +0,0 @@
-error: struct literals are not allowed here
-  --> $DIR/struct-literal-in-match-discriminant.rs:6:11
-   |
-LL |       match Foo {
-   |  ___________^
-LL | |         x: 3
-LL | |     } {
-   | |_____^
-   |
-help: surround the struct literal with parentheses
-   |
-LL ~     match (Foo {
-LL |         x: 3
-LL ~     }) {
-   |
-
-error: aborting due to 1 previous error
-
diff --git a/tests/ui/parser/struct-literal-in-while.rs b/tests/ui/parser/struct-literal-in-while.rs
deleted file mode 100644
index 86931f7888d..00000000000
--- a/tests/ui/parser/struct-literal-in-while.rs
+++ /dev/null
@@ -1,22 +0,0 @@
-struct Foo {
-    x: isize,
-}
-
-impl Foo {
-    fn hi(&self) -> bool {
-        true
-    }
-}
-
-fn main() {
-    while Foo { //~ ERROR struct literals are not allowed here
-        x: 3
-    }.hi() {
-        println!("yo");
-    }
-    while let true = Foo { //~ ERROR struct literals are not allowed here
-        x: 3
-    }.hi() {
-        println!("yo");
-    }
-}
diff --git a/tests/ui/parser/struct-literal-in-while.stderr b/tests/ui/parser/struct-literal-in-while.stderr
deleted file mode 100644
index 13d003608a1..00000000000
--- a/tests/ui/parser/struct-literal-in-while.stderr
+++ /dev/null
@@ -1,34 +0,0 @@
-error: struct literals are not allowed here
-  --> $DIR/struct-literal-in-while.rs:12:11
-   |
-LL |       while Foo {
-   |  ___________^
-LL | |         x: 3
-LL | |     }.hi() {
-   | |_____^
-   |
-help: surround the struct literal with parentheses
-   |
-LL ~     while (Foo {
-LL |         x: 3
-LL ~     }).hi() {
-   |
-
-error: struct literals are not allowed here
-  --> $DIR/struct-literal-in-while.rs:17:22
-   |
-LL |       while let true = Foo {
-   |  ______________________^
-LL | |         x: 3
-LL | |     }.hi() {
-   | |_____^
-   |
-help: surround the struct literal with parentheses
-   |
-LL ~     while let true = (Foo {
-LL |         x: 3
-LL ~     }).hi() {
-   |
-
-error: aborting due to 2 previous errors
-
diff --git a/tests/ui/parser/struct-literal-restrictions-in-lamda.rs b/tests/ui/parser/struct-literal-restrictions-in-lamda.rs
deleted file mode 100644
index e185153dcf6..00000000000
--- a/tests/ui/parser/struct-literal-restrictions-in-lamda.rs
+++ /dev/null
@@ -1,17 +0,0 @@
-struct Foo {
-    x: isize,
-}
-
-impl Foo {
-    fn hi(&self) -> bool {
-        true
-    }
-}
-
-fn main() {
-    while || Foo { //~ ERROR struct literals are not allowed here
-        x: 3       //~^ ERROR mismatched types
-    }.hi() {
-        println!("yo");
-    }
-}
diff --git a/tests/ui/parser/struct-literal-restrictions-in-lamda.stderr b/tests/ui/parser/struct-literal-restrictions-in-lamda.stderr
deleted file mode 100644
index c715486e2da..00000000000
--- a/tests/ui/parser/struct-literal-restrictions-in-lamda.stderr
+++ /dev/null
@@ -1,37 +0,0 @@
-error: struct literals are not allowed here
-  --> $DIR/struct-literal-restrictions-in-lamda.rs:12:14
-   |
-LL |       while || Foo {
-   |  ______________^
-LL | |         x: 3
-LL | |     }.hi() {
-   | |_____^
-   |
-help: surround the struct literal with parentheses
-   |
-LL ~     while || (Foo {
-LL |         x: 3
-LL ~     }).hi() {
-   |
-
-error[E0308]: mismatched types
-  --> $DIR/struct-literal-restrictions-in-lamda.rs:12:11
-   |
-LL |       while || Foo {
-   |  ___________^
-LL | |         x: 3
-LL | |     }.hi() {
-   | |__________^ expected `bool`, found closure
-   |
-   = note: expected type `bool`
-           found closure `{closure@$DIR/struct-literal-restrictions-in-lamda.rs:12:11: 12:13}`
-help: use parentheses to call this closure
-   |
-LL ~     while (|| Foo {
-LL |         x: 3
-LL ~     }.hi())() {
-   |
-
-error: aborting due to 2 previous errors
-
-For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/parser/struct-literal-variant-in-if.rs b/tests/ui/parser/struct-literal-variant-in-if.rs
deleted file mode 100644
index 4ef8effaf1f..00000000000
--- a/tests/ui/parser/struct-literal-variant-in-if.rs
+++ /dev/null
@@ -1,25 +0,0 @@
-#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
-enum E {
-    V { field: bool },
-    I { field1: bool, field2: usize },
-    J { field: isize },
-    K { field: &'static str},
-}
-fn test_E(x: E) {
-    let field = true;
-    if x == E::V { field } {}
-    //~^ ERROR expected value, found struct variant `E::V`
-    //~| ERROR mismatched types
-    if x == E::I { field1: true, field2: 42 } {}
-    //~^ ERROR struct literals are not allowed here
-    if x == E::V { field: false } {}
-    //~^ ERROR struct literals are not allowed here
-    if x == E::J { field: -42 } {}
-    //~^ ERROR struct literals are not allowed here
-    if x == E::K { field: "" } {}
-    //~^ ERROR struct literals are not allowed here
-    let y: usize = ();
-    //~^ ERROR mismatched types
-}
-
-fn main() {}
diff --git a/tests/ui/parser/struct-literal-variant-in-if.stderr b/tests/ui/parser/struct-literal-variant-in-if.stderr
deleted file mode 100644
index 15f059f145b..00000000000
--- a/tests/ui/parser/struct-literal-variant-in-if.stderr
+++ /dev/null
@@ -1,76 +0,0 @@
-error: struct literals are not allowed here
-  --> $DIR/struct-literal-variant-in-if.rs:13:13
-   |
-LL |     if x == E::I { field1: true, field2: 42 } {}
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: surround the struct literal with parentheses
-   |
-LL |     if x == (E::I { field1: true, field2: 42 }) {}
-   |             +                                 +
-
-error: struct literals are not allowed here
-  --> $DIR/struct-literal-variant-in-if.rs:15:13
-   |
-LL |     if x == E::V { field: false } {}
-   |             ^^^^^^^^^^^^^^^^^^^^^
-   |
-help: surround the struct literal with parentheses
-   |
-LL |     if x == (E::V { field: false }) {}
-   |             +                     +
-
-error: struct literals are not allowed here
-  --> $DIR/struct-literal-variant-in-if.rs:17:13
-   |
-LL |     if x == E::J { field: -42 } {}
-   |             ^^^^^^^^^^^^^^^^^^^
-   |
-help: surround the struct literal with parentheses
-   |
-LL |     if x == (E::J { field: -42 }) {}
-   |             +                   +
-
-error: struct literals are not allowed here
-  --> $DIR/struct-literal-variant-in-if.rs:19:13
-   |
-LL |     if x == E::K { field: "" } {}
-   |             ^^^^^^^^^^^^^^^^^^
-   |
-help: surround the struct literal with parentheses
-   |
-LL |     if x == (E::K { field: "" }) {}
-   |             +                  +
-
-error[E0533]: expected value, found struct variant `E::V`
-  --> $DIR/struct-literal-variant-in-if.rs:10:13
-   |
-LL |     if x == E::V { field } {}
-   |             ^^^^ not a value
-   |
-help: you might have meant to create a new value of the struct
-   |
-LL |     if x == (E::V { field }) {}
-   |             +              +
-
-error[E0308]: mismatched types
-  --> $DIR/struct-literal-variant-in-if.rs:10:20
-   |
-LL |     if x == E::V { field } {}
-   |     ---------------^^^^^--
-   |     |              |
-   |     |              expected `()`, found `bool`
-   |     expected this to be `()`
-
-error[E0308]: mismatched types
-  --> $DIR/struct-literal-variant-in-if.rs:21:20
-   |
-LL |     let y: usize = ();
-   |            -----   ^^ expected `usize`, found `()`
-   |            |
-   |            expected due to this
-
-error: aborting due to 7 previous errors
-
-Some errors have detailed explanations: E0308, E0533.
-For more information about an error, try `rustc --explain E0308`.
diff --git a/tests/ui/parser/struct-literals-in-invalid-places.rs b/tests/ui/parser/struct-literals-in-invalid-places.rs
new file mode 100644
index 00000000000..eed51b94583
--- /dev/null
+++ b/tests/ui/parser/struct-literals-in-invalid-places.rs
@@ -0,0 +1,92 @@
+fn main() {
+    if Foo { x: 3 }.hi() { //~ ERROR struct literals are not allowed here
+        println!("yo");
+    }
+    if let true = Foo { x: 3 }.hi() { //~ ERROR struct literals are not allowed here
+        println!("yo");
+    }
+
+    for x in Foo { x: 3 }.hi() { //~ ERROR struct literals are not allowed here
+        //~^ ERROR `bool` is not an iterator
+        println!("yo");
+    }
+
+    while Foo { x: 3 }.hi() { //~ ERROR struct literals are not allowed here
+        println!("yo");
+    }
+    while let true = Foo { x: 3 }.hi() { //~ ERROR struct literals are not allowed here
+        println!("yo");
+    }
+
+    match Foo { x: 3 } { //~ ERROR struct literals are not allowed here
+        Foo { x: x } => {}
+    }
+
+    let _ = |x: E| {
+        let field = true;
+        if x == E::V { field } {}
+        //~^ ERROR expected value, found struct variant `E::V`
+        //~| ERROR mismatched types
+        if x == E::I { field1: true, field2: 42 } {}
+        //~^ ERROR struct literals are not allowed here
+        if x == E::V { field: false } {}
+        //~^ ERROR struct literals are not allowed here
+        if x == E::J { field: -42 } {}
+        //~^ ERROR struct literals are not allowed here
+        if x == E::K { field: "" } {}
+        //~^ ERROR struct literals are not allowed here
+        let y: usize = ();
+        //~^ ERROR mismatched types
+    };
+
+    // Regression test for <https://github.com/rust-lang/rust/issues/43412>.
+    while || Foo { x: 3 }.hi() { //~ ERROR struct literals are not allowed here
+        //~^ ERROR mismatched types
+        println!("yo");
+    }
+
+    // This uses `one()` over `1` as token `one` may begin a type and thus back when type ascription
+    // `$expr : $ty` still existed, `{ x: one` could've been the start of a block expr which used to
+    // make the compiler take a different execution path. Now it no longer makes a difference tho.
+
+    // Regression test for <https://github.com/rust-lang/rust/issues/82051>.
+    if Foo { x: one(), }.hi() { //~ ERROR struct literals are not allowed here
+        println!("Positive!");
+    }
+
+    const FOO: Foo = Foo { x: 1 };
+    // Below, test that we correctly parenthesize the struct literals.
+
+    // Regression test for <https://github.com/rust-lang/rust/issues/112278>.
+    if FOO == self::Foo { x: one() } {} //~ ERROR struct literals are not allowed here
+
+    if FOO == Foo::<> { x: one() } {} //~ ERROR struct literals are not allowed here
+
+    fn env<T: Trait<Out = Foo>>() {
+        if FOO == <T as Trait>::Out { x: one() } {} //~ ERROR struct literals are not allowed here
+        //~^ ERROR usage of qualified paths in this context is experimental
+    }
+}
+
+#[derive(PartialEq, Eq)]
+struct Foo {
+    x: isize,
+}
+
+impl Foo {
+    fn hi(&self) -> bool {
+        true
+    }
+}
+
+#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
+enum E {
+    V { field: bool },
+    I { field1: bool, field2: usize },
+    J { field: isize },
+    K { field: &'static str},
+}
+
+fn one() -> isize { 1 }
+
+trait Trait { type Out; }
diff --git a/tests/ui/parser/struct-literals-in-invalid-places.stderr b/tests/ui/parser/struct-literals-in-invalid-places.stderr
new file mode 100644
index 00000000000..39dc2d2efb7
--- /dev/null
+++ b/tests/ui/parser/struct-literals-in-invalid-places.stderr
@@ -0,0 +1,234 @@
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:2:8
+   |
+LL |     if Foo { x: 3 }.hi() {
+   |        ^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |     if (Foo { x: 3 }).hi() {
+   |        +            +
+
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:5:19
+   |
+LL |     if let true = Foo { x: 3 }.hi() {
+   |                   ^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |     if let true = (Foo { x: 3 }).hi() {
+   |                   +            +
+
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:9:14
+   |
+LL |     for x in Foo { x: 3 }.hi() {
+   |              ^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |     for x in (Foo { x: 3 }).hi() {
+   |              +            +
+
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:14:11
+   |
+LL |     while Foo { x: 3 }.hi() {
+   |           ^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |     while (Foo { x: 3 }).hi() {
+   |           +            +
+
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:17:22
+   |
+LL |     while let true = Foo { x: 3 }.hi() {
+   |                      ^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |     while let true = (Foo { x: 3 }).hi() {
+   |                      +            +
+
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:21:11
+   |
+LL |     match Foo { x: 3 } {
+   |           ^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |     match (Foo { x: 3 }) {
+   |           +            +
+
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:30:17
+   |
+LL |         if x == E::I { field1: true, field2: 42 } {}
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |         if x == (E::I { field1: true, field2: 42 }) {}
+   |                 +                                 +
+
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:32:17
+   |
+LL |         if x == E::V { field: false } {}
+   |                 ^^^^^^^^^^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |         if x == (E::V { field: false }) {}
+   |                 +                     +
+
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:34:17
+   |
+LL |         if x == E::J { field: -42 } {}
+   |                 ^^^^^^^^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |         if x == (E::J { field: -42 }) {}
+   |                 +                   +
+
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:36:17
+   |
+LL |         if x == E::K { field: "" } {}
+   |                 ^^^^^^^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |         if x == (E::K { field: "" }) {}
+   |                 +                  +
+
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:43:14
+   |
+LL |     while || Foo { x: 3 }.hi() {
+   |              ^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |     while || (Foo { x: 3 }).hi() {
+   |              +            +
+
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:53:8
+   |
+LL |     if Foo { x: one(), }.hi() {
+   |        ^^^^^^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |     if (Foo { x: one(), }).hi() {
+   |        +                 +
+
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:61:15
+   |
+LL |     if FOO == self::Foo { x: one() } {}
+   |               ^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |     if FOO == (self::Foo { x: one() }) {}
+   |               +                      +
+
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:63:15
+   |
+LL |     if FOO == Foo::<> { x: one() } {}
+   |               ^^^^^^^^^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |     if FOO == (Foo::<> { x: one() }) {}
+   |               +                    +
+
+error: struct literals are not allowed here
+  --> $DIR/struct-literals-in-invalid-places.rs:66:19
+   |
+LL |         if FOO == <T as Trait>::Out { x: one() } {}
+   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: surround the struct literal with parentheses
+   |
+LL |         if FOO == (<T as Trait>::Out { x: one() }) {}
+   |                   +                              +
+
+error[E0658]: usage of qualified paths in this context is experimental
+  --> $DIR/struct-literals-in-invalid-places.rs:66:19
+   |
+LL |         if FOO == <T as Trait>::Out { x: one() } {}
+   |                   ^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #86935 <https://github.com/rust-lang/rust/issues/86935> for more information
+   = help: add `#![feature(more_qualified_paths)]` 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[E0277]: `bool` is not an iterator
+  --> $DIR/struct-literals-in-invalid-places.rs:9:14
+   |
+LL |     for x in Foo { x: 3 }.hi() {
+   |              ^^^^^^^^^^^^^^^^^ `bool` is not an iterator
+   |
+   = help: the trait `Iterator` is not implemented for `bool`
+   = note: required for `bool` to implement `IntoIterator`
+
+error[E0533]: expected value, found struct variant `E::V`
+  --> $DIR/struct-literals-in-invalid-places.rs:27:17
+   |
+LL |         if x == E::V { field } {}
+   |                 ^^^^ not a value
+   |
+help: you might have meant to create a new value of the struct
+   |
+LL |         if x == (E::V { field }) {}
+   |                 +              +
+
+error[E0308]: mismatched types
+  --> $DIR/struct-literals-in-invalid-places.rs:27:24
+   |
+LL |         if x == E::V { field } {}
+   |         ---------------^^^^^--
+   |         |              |
+   |         |              expected `()`, found `bool`
+   |         expected this to be `()`
+   |
+help: you might have meant to return this value
+   |
+LL |         if x == E::V { return field; } {}
+   |                        ++++++      +
+
+error[E0308]: mismatched types
+  --> $DIR/struct-literals-in-invalid-places.rs:38:24
+   |
+LL |         let y: usize = ();
+   |                -----   ^^ expected `usize`, found `()`
+   |                |
+   |                expected due to this
+
+error[E0308]: mismatched types
+  --> $DIR/struct-literals-in-invalid-places.rs:43:11
+   |
+LL |     while || Foo { x: 3 }.hi() {
+   |           ^^^^^^^^^^^^^^^^^^^^ expected `bool`, found closure
+   |
+   = note: expected type `bool`
+           found closure `{closure@$DIR/struct-literals-in-invalid-places.rs:43:11: 43:13}`
+help: use parentheses to call this closure
+   |
+LL |     while (|| Foo { x: 3 }.hi())() {
+   |           +                    +++
+
+error: aborting due to 21 previous errors
+
+Some errors have detailed explanations: E0277, E0308, E0533, E0658.
+For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/parser/type-ascription-in-pattern.rs b/tests/ui/parser/type-ascription-in-pattern.rs
index fec168afba1..18d7061d69c 100644
--- a/tests/ui/parser/type-ascription-in-pattern.rs
+++ b/tests/ui/parser/type-ascription-in-pattern.rs
@@ -1,11 +1,10 @@
 fn foo(x: bool) -> i32 {
-    match x {
+    match x { //~ ERROR struct literals are not allowed here
         x: i32 => x, //~ ERROR expected
-        //~^ ERROR mismatched types
-        true => 42.,
-        false => 0.333,
+        true => 42., //~ ERROR expected identifier
+        false => 0.333, //~ ERROR expected identifier
     }
-}
+} //~ ERROR expected one of
 
 fn main() {
     match foo(true) {
diff --git a/tests/ui/parser/type-ascription-in-pattern.stderr b/tests/ui/parser/type-ascription-in-pattern.stderr
index 09190754993..135879f208b 100644
--- a/tests/ui/parser/type-ascription-in-pattern.stderr
+++ b/tests/ui/parser/type-ascription-in-pattern.stderr
@@ -1,18 +1,64 @@
-error: expected one of `@` or `|`, found `:`
-  --> $DIR/type-ascription-in-pattern.rs:3:10
+error: expected one of `!`, `,`, `.`, `::`, `?`, `{`, `}`, or an operator, found `=>`
+  --> $DIR/type-ascription-in-pattern.rs:3:16
    |
+LL |     match x {
+   |           - while parsing this struct
 LL |         x: i32 => x,
-   |          ^ --- specifying the type of a pattern isn't supported
-   |          |
-   |          expected one of `@` or `|`
+   |               -^^ expected one of 8 possible tokens
+   |               |
+   |               help: try adding a comma: `,`
+
+error: expected identifier, found keyword `true`
+  --> $DIR/type-ascription-in-pattern.rs:4:9
    |
-help: maybe write a path separator here
+LL |     match x {
+   |           - while parsing this struct
+LL |         x: i32 => x,
+LL |         true => 42.,
+   |         ^^^^ expected identifier, found keyword
+
+error: expected identifier, found keyword `false`
+  --> $DIR/type-ascription-in-pattern.rs:5:9
    |
-LL |         x::i32 => x,
-   |          ~~
+LL |     match x {
+   |           - while parsing this struct
+...
+LL |         false => 0.333,
+   |         ^^^^^ expected identifier, found keyword
+
+error: struct literals are not allowed here
+  --> $DIR/type-ascription-in-pattern.rs:2:11
+   |
+LL |       match x {
+   |  ___________^
+LL | |         x: i32 => x,
+LL | |         true => 42.,
+LL | |         false => 0.333,
+LL | |     }
+   | |_____^
+   |
+help: surround the struct literal with parentheses
+   |
+LL ~     match (x {
+LL |         x: i32 => x,
+LL |         true => 42.,
+LL |         false => 0.333,
+LL ~     })
+   |
+
+error: expected one of `.`, `?`, `{`, or an operator, found `}`
+  --> $DIR/type-ascription-in-pattern.rs:7:1
+   |
+LL |     match x {
+   |     ----- while parsing this `match` expression
+...
+LL |     }
+   |      - expected one of `.`, `?`, `{`, or an operator
+LL | }
+   | ^ unexpected token
 
 error: expected one of `...`, `..=`, `..`, or `|`, found `:`
-  --> $DIR/type-ascription-in-pattern.rs:12:11
+  --> $DIR/type-ascription-in-pattern.rs:11:11
    |
 LL |         42: i32 => (),
    |           ^ --- specifying the type of a pattern isn't supported
@@ -20,7 +66,7 @@ LL |         42: i32 => (),
    |           expected one of `...`, `..=`, `..`, or `|`
 
 error: expected `|`, found `:`
-  --> $DIR/type-ascription-in-pattern.rs:13:10
+  --> $DIR/type-ascription-in-pattern.rs:12:10
    |
 LL |         _: f64 => (),
    |          ^ --- specifying the type of a pattern isn't supported
@@ -28,7 +74,7 @@ LL |         _: f64 => (),
    |          expected `|`
 
 error: expected one of `@` or `|`, found `:`
-  --> $DIR/type-ascription-in-pattern.rs:14:10
+  --> $DIR/type-ascription-in-pattern.rs:13:10
    |
 LL |         x: i32 => (),
    |          ^ --- specifying the type of a pattern isn't supported
@@ -40,15 +86,5 @@ help: maybe write a path separator here
 LL |         x::i32 => (),
    |          ~~
 
-error[E0308]: mismatched types
-  --> $DIR/type-ascription-in-pattern.rs:3:19
-   |
-LL | fn foo(x: bool) -> i32 {
-   |                    --- expected `i32` because of return type
-LL |     match x {
-LL |         x: i32 => x,
-   |                   ^ expected `i32`, found `bool`
-
-error: aborting due to 5 previous errors
+error: aborting due to 8 previous errors
 
-For more information about this error, try `rustc --explain E0308`.