Rollup merge of #87101 - FabianWolff:issue-87086, r=estebank

Suggest a path separator if a stray colon is found in a match arm

Attempts to fix #87086.

r? `@estebank`

2 files changed, 134 insertions, 0 deletions

diff --git a/src/test/ui/parser/issue-87086-colon-path-sep.rs b/src/test/ui/parser/issue-87086-colon-path-sep.rs
new file mode 100644
index 00000000000..4ee0b2054ff
--- /dev/null
+++ b/src/test/ui/parser/issue-87086-colon-path-sep.rs
@@ -0,0 +1,66 @@
+// Tests that a suggestion is issued if the user wrote a colon instead of
+// a path separator in a match arm.
+
+enum Foo {
+    Bar,
+    Baz,
+}
+
+fn f() -> Foo { Foo::Bar }
+
+fn g1() {
+    match f() {
+        Foo:Bar => {}
+        //~^ ERROR: expected one of
+        //~| HELP: maybe write a path separator here
+        _ => {}
+    }
+    match f() {
+        Foo::Bar:Baz => {}
+        //~^ ERROR: expected one of
+        //~| HELP: maybe write a path separator here
+        _ => {}
+    }
+    match f() {
+        Foo:Bar::Baz => {}
+        //~^ ERROR: expected one of
+        //~| HELP: maybe write a path separator here
+        _ => {}
+    }
+    match f() {
+        Foo: Bar::Baz if true => {}
+        //~^ ERROR: expected one of
+        //~| HELP: maybe write a path separator here
+        _ => {}
+    }
+    if let Bar:Baz = f() {
+    //~^ ERROR: expected one of
+    //~| HELP: maybe write a path separator here
+    }
+}
+
+fn g1_neg() {
+    match f() {
+        ref Foo: Bar::Baz => {}
+        //~^ ERROR: expected one of
+        _ => {}
+    }
+}
+
+fn g2_neg() {
+    match f() {
+        mut Foo: Bar::Baz => {}
+        //~^ ERROR: expected one of
+        _ => {}
+    }
+}
+
+fn main() {
+    let myfoo = Foo::Bar;
+    match myfoo {
+        Foo::Bar => {}
+        Foo:Bar::Baz => {}
+        //~^ ERROR: expected one of
+        //~| HELP: maybe write a path separator here
+    }
+}
diff --git a/src/test/ui/parser/issue-87086-colon-path-sep.stderr b/src/test/ui/parser/issue-87086-colon-path-sep.stderr
new file mode 100644
index 00000000000..8f93661a626
--- /dev/null
+++ b/src/test/ui/parser/issue-87086-colon-path-sep.stderr
@@ -0,0 +1,68 @@
+error: expected one of `@` or `|`, found `:`
+  --> $DIR/issue-87086-colon-path-sep.rs:13:12
+   |
+LL |         Foo:Bar => {}
+   |            ^
+   |            |
+   |            expected one of `@` or `|`
+   |            help: maybe write a path separator here: `::`
+
+error: expected one of `!`, `(`, `...`, `..=`, `..`, `::`, `{`, or `|`, found `:`
+  --> $DIR/issue-87086-colon-path-sep.rs:19:17
+   |
+LL |         Foo::Bar:Baz => {}
+   |                 ^
+   |                 |
+   |                 expected one of 8 possible tokens
+   |                 help: maybe write a path separator here: `::`
+
+error: expected one of `@` or `|`, found `:`
+  --> $DIR/issue-87086-colon-path-sep.rs:25:12
+   |
+LL |         Foo:Bar::Baz => {}
+   |            ^
+   |            |
+   |            expected one of `@` or `|`
+   |            help: maybe write a path separator here: `::`
+
+error: expected one of `@` or `|`, found `:`
+  --> $DIR/issue-87086-colon-path-sep.rs:31:12
+   |
+LL |         Foo: Bar::Baz if true => {}
+   |            ^
+   |            |
+   |            expected one of `@` or `|`
+   |            help: maybe write a path separator here: `::`
+
+error: expected one of `@` or `|`, found `:`
+  --> $DIR/issue-87086-colon-path-sep.rs:36:15
+   |
+LL |     if let Bar:Baz = f() {
+   |               ^
+   |               |
+   |               expected one of `@` or `|`
+   |               help: maybe write a path separator here: `::`
+
+error: expected one of `=>`, `@`, `if`, or `|`, found `:`
+  --> $DIR/issue-87086-colon-path-sep.rs:44:16
+   |
+LL |         ref Foo: Bar::Baz => {}
+   |                ^ expected one of `=>`, `@`, `if`, or `|`
+
+error: expected one of `=>`, `@`, `if`, or `|`, found `:`
+  --> $DIR/issue-87086-colon-path-sep.rs:52:16
+   |
+LL |         mut Foo: Bar::Baz => {}
+   |                ^ expected one of `=>`, `@`, `if`, or `|`
+
+error: expected one of `@` or `|`, found `:`
+  --> $DIR/issue-87086-colon-path-sep.rs:62:12
+   |
+LL |         Foo:Bar::Baz => {}
+   |            ^
+   |            |
+   |            expected one of `@` or `|`
+   |            help: maybe write a path separator here: `::`
+
+error: aborting due to 8 previous errors
+