Tweak handling of "struct like start" where a struct isn't supported

This improves the case where someone tries to write a `match` expr where the patterns have type ascription syntax. Makes them less verbose, by giving up on the first encounter in the block, and makes them more accurate by only treating them as a struct literal if successfuly parsed as such.

4 files changed, 37 insertions, 83 deletions

diff --git a/tests/ui/parser/issues/issue-87086-colon-path-sep.rs b/tests/ui/parser/issues/issue-87086-colon-path-sep.rs
index d081c06044f..e1ea38f2795 100644
--- a/tests/ui/parser/issues/issue-87086-colon-path-sep.rs
+++ b/tests/ui/parser/issues/issue-87086-colon-path-sep.rs
@@ -37,10 +37,9 @@ fn g1() {
         //~| HELP: maybe write a path separator here
         _ => {}
     }
-    if let Foo:Bar = f() { //~ WARN: irrefutable `if let` pattern
+    if let Foo:Bar = f() {
     //~^ ERROR: expected one of
     //~| HELP: maybe write a path separator here
-    //~| HELP: consider replacing the `if let` with a `let`
     }
 }
 
diff --git a/tests/ui/parser/issues/issue-87086-colon-path-sep.stderr b/tests/ui/parser/issues/issue-87086-colon-path-sep.stderr
index a9bad96f9af..061586882e0 100644
--- a/tests/ui/parser/issues/issue-87086-colon-path-sep.stderr
+++ b/tests/ui/parser/issues/issue-87086-colon-path-sep.stderr
@@ -64,7 +64,7 @@ LL |     if let Foo::Bar = f() {
    |                +
 
 error: expected one of `@` or `|`, found `:`
-  --> $DIR/issue-87086-colon-path-sep.rs:49:16
+  --> $DIR/issue-87086-colon-path-sep.rs:48:16
    |
 LL |         ref qux: Foo::Baz => {}
    |                ^ -------- specifying the type of a pattern isn't supported
@@ -77,7 +77,7 @@ LL |         ref qux::Foo::Baz => {}
    |                ~~
 
 error: expected one of `@` or `|`, found `:`
-  --> $DIR/issue-87086-colon-path-sep.rs:58:16
+  --> $DIR/issue-87086-colon-path-sep.rs:57:16
    |
 LL |         mut qux: Foo::Baz => {}
    |                ^ -------- specifying the type of a pattern isn't supported
@@ -90,7 +90,7 @@ LL |         mut qux::Foo::Baz => {}
    |                ~~
 
 error: expected one of `@` or `|`, found `:`
-  --> $DIR/issue-87086-colon-path-sep.rs:69:12
+  --> $DIR/issue-87086-colon-path-sep.rs:68:12
    |
 LL |         Foo:Bar::Baz => {}
    |            ^-------- specifying the type of a pattern isn't supported
@@ -103,7 +103,7 @@ LL |         Foo::Bar::Baz => {}
    |             +
 
 error: expected one of `@` or `|`, found `:`
-  --> $DIR/issue-87086-colon-path-sep.rs:75:12
+  --> $DIR/issue-87086-colon-path-sep.rs:74:12
    |
 LL |         Foo:Bar => {}
    |            ^--- specifying the type of a pattern isn't supported
@@ -115,15 +115,5 @@ help: maybe write a path separator here
 LL |         Foo::Bar => {}
    |             +
 
-warning: irrefutable `if let` pattern
-  --> $DIR/issue-87086-colon-path-sep.rs:40:8
-   |
-LL |     if let Foo:Bar = f() {
-   |        ^^^^^^^^^^^^^^^^^
-   |
-   = note: this pattern will always match, so the `if let` is useless
-   = help: consider replacing the `if let` with a `let`
-   = note: `#[warn(irrefutable_let_patterns)]` on by default
-
-error: aborting due to 9 previous errors; 1 warning emitted
+error: aborting due to 9 previous errors
 
diff --git a/tests/ui/parser/type-ascription-in-pattern.rs b/tests/ui/parser/type-ascription-in-pattern.rs
index 18d7061d69c..75059d33db6 100644
--- a/tests/ui/parser/type-ascription-in-pattern.rs
+++ b/tests/ui/parser/type-ascription-in-pattern.rs
@@ -1,15 +1,16 @@
 fn foo(x: bool) -> i32 {
-    match x { //~ ERROR struct literals are not allowed here
-        x: i32 => x, //~ ERROR expected
-        true => 42., //~ ERROR expected identifier
-        false => 0.333, //~ ERROR expected identifier
+    match x {
+        x: i32 => x, //~ ERROR: expected
+        //~^ ERROR: mismatched types
+        true => 42.,
+        false => 0.333,
     }
-} //~ ERROR expected one of
+}
 
 fn main() {
     match foo(true) {
-        42: i32 => (), //~ ERROR expected
-        _: f64 => (), //~ ERROR expected
-        x: i32 => (), //~ ERROR expected
+        42: i32 => (), //~ ERROR: expected
+        _: f64 => (), //~ ERROR: expected
+        x: i32 => (), //~ ERROR: expected
     }
 }
diff --git a/tests/ui/parser/type-ascription-in-pattern.stderr b/tests/ui/parser/type-ascription-in-pattern.stderr
index 135879f208b..09190754993 100644
--- a/tests/ui/parser/type-ascription-in-pattern.stderr
+++ b/tests/ui/parser/type-ascription-in-pattern.stderr
@@ -1,64 +1,18 @@
-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,
-   |               -^^ 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
-   |
-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 |     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
+error: expected one of `@` or `|`, found `:`
+  --> $DIR/type-ascription-in-pattern.rs:3:10
    |
-LL ~     match (x {
 LL |         x: i32 => x,
-LL |         true => 42.,
-LL |         false => 0.333,
-LL ~     })
+   |          ^ --- specifying the type of a pattern isn't supported
+   |          |
+   |          expected one of `@` or `|`
    |
-
-error: expected one of `.`, `?`, `{`, or an operator, found `}`
-  --> $DIR/type-ascription-in-pattern.rs:7:1
+help: maybe write a path separator here
    |
-LL |     match x {
-   |     ----- while parsing this `match` expression
-...
-LL |     }
-   |      - expected one of `.`, `?`, `{`, or an operator
-LL | }
-   | ^ unexpected token
+LL |         x::i32 => x,
+   |          ~~
 
 error: expected one of `...`, `..=`, `..`, or `|`, found `:`
-  --> $DIR/type-ascription-in-pattern.rs:11:11
+  --> $DIR/type-ascription-in-pattern.rs:12:11
    |
 LL |         42: i32 => (),
    |           ^ --- specifying the type of a pattern isn't supported
@@ -66,7 +20,7 @@ LL |         42: i32 => (),
    |           expected one of `...`, `..=`, `..`, or `|`
 
 error: expected `|`, found `:`
-  --> $DIR/type-ascription-in-pattern.rs:12:10
+  --> $DIR/type-ascription-in-pattern.rs:13:10
    |
 LL |         _: f64 => (),
    |          ^ --- specifying the type of a pattern isn't supported
@@ -74,7 +28,7 @@ LL |         _: f64 => (),
    |          expected `|`
 
 error: expected one of `@` or `|`, found `:`
-  --> $DIR/type-ascription-in-pattern.rs:13:10
+  --> $DIR/type-ascription-in-pattern.rs:14:10
    |
 LL |         x: i32 => (),
    |          ^ --- specifying the type of a pattern isn't supported
@@ -86,5 +40,15 @@ help: maybe write a path separator here
 LL |         x::i32 => (),
    |          ~~
 
-error: aborting due to 8 previous errors
+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
 
+For more information about this error, try `rustc --explain E0308`.