add regression tests for overlapping spans

Author: lqd

tests/ui/span/auxiliary/overlapping_spans_helper.rs

@@ -0,0 +1,15 @@
+// Auxiliary lib for the issue 147973 regression test with ICEs due to overlapping spans.
+
+#[macro_export]
+macro_rules! identity {
+    ($x:ident) => {
+        $x
+    };
+}
+
+#[macro_export]
+macro_rules! do_loop {
+    ($x:ident) => {
+        for $crate::identity!($x) in $x {}
+    };
+}

tests/ui/span/overlapping-spans-in-suggestions.rs

@@ -0,0 +1,38 @@
+// These are regression tests for some diagnostics ICEs encountered in the wild with suggestions
+// having overlapping parts under https://github.com/rust-lang/rust/pull/146121.
+
+//@ aux-build: overlapping_spans_helper.rs
+extern crate overlapping_spans_helper;
+
+// MCVE from issue 146261
+enum U {
+    B(),
+}
+
+fn mcve_146261() {
+    A(U::C)
+    //~^ ERROR: cannot find function, tuple struct or tuple variant `A`
+    //~| ERROR: no variant or associated item named `C`
+}
+
+// MCVE from issue 146706
+
+type Alias<'a, T> = Foo<T>;
+
+enum Foo<T> {
+    Bar { t: T },
+}
+
+fn mcve_146706() {
+    Alias::Bar::<u32> { t: 0 };
+    //~^ ERROR: type arguments are not allowed on this type
+}
+
+// One MCVE from the beta crater run from issue 147973
+
+fn mcve_147973() {
+    let _name = Some(1);
+    overlapping_spans_helper::do_loop!(_name);
+}
+
+fn main() {}

tests/ui/span/overlapping-spans-in-suggestions.stderr

@@ -0,0 +1,45 @@
+error[E0425]: cannot find function, tuple struct or tuple variant `A` in this scope
+  --> $DIR/overlapping-spans-in-suggestions.rs:13:5
+   |
+LL |     A(U::C)
+   |     ^ not found in this scope
+   |
+help: you might be missing a const parameter
+   |
+LL | fn mcve_146261<const A: /* Type */>() {
+   |               +++++++++++++++++++++
+
+error[E0599]: no variant or associated item named `C` found for enum `U` in the current scope
+  --> $DIR/overlapping-spans-in-suggestions.rs:13:10
+   |
+LL | enum U {
+   | ------ variant or associated item `C` not found for this enum
+...
+LL |     A(U::C)
+   |          ^ variant or associated item not found in `U`
+   |
+help: there is a variant with a similar name
+   |
+LL -     A(U::C)
+LL +     A(B)
+   |
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/overlapping-spans-in-suggestions.rs:27:18
+   |
+LL |     Alias::Bar::<u32> { t: 0 };
+   |            ---   ^^^ type argument not allowed
+   |            |
+   |            not allowed on this type
+   |
+   = note: enum variants can't have type parameters
+help: you might have meant to specify type parameters on enum `Foo`
+   |
+LL -     Alias::Bar::<u32> { t: 0 };
+LL +     Alias::<u32> { t: 0 };
+   |
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0109, E0425, E0599.
+For more information about an error, try `rustc --explain E0109`.