Make output more specific

Author: estebank

compiler/rustc_typeck/src/astconv/mod.rs

@@ -2108,6 +2108,46 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         extend: impl Fn(&mut DiagnosticBuilder<'tcx, ErrorGuaranteed>),
     ) -> bool {
         let args = segments.clone().flat_map(|segment| segment.args().args);
+        let types_and_spans: Vec<_> = segments
+            .clone()
+            .flat_map(|segment| {
+                segment.res.and_then(|res| {
+                    if segment.args().args.is_empty() {
+                        None
+                    } else {
+                        let mut desc = res.descr();
+                        if desc == "unresolved item" {
+                            desc = "this type";
+                        };
+
+                        let name = match res {
+                            Res::PrimTy(ty) => Some(ty.name()),
+                            Res::Def(_, def_id) => self.tcx().opt_item_name(def_id),
+                            _ => None,
+                        };
+                        Some((
+                            match name {
+                                Some(ty) => format!("{desc} `{ty}`"),
+                                None => desc.to_string(),
+                            },
+                            segment.ident.span,
+                        ))
+                    }
+                })
+            })
+            .collect();
+        let this_type = match &types_and_spans[..] {
+            [.., _, (last, _)] => format!(
+                "{} and {last}",
+                types_and_spans[..types_and_spans.len() - 1]
+                    .iter()
+                    .map(|(x, _)| x.as_str())
+                    .intersperse(&", ")
+                    .collect::<String>()
+            ),
+            [(only, _)] => only.to_string(),
+            [] => "this type".to_string(),
+        };
 
         let (lt, ty, ct, inf) =
             args.clone().fold((false, false, false, false), |(lt, ty, ct, inf), arg| match arg {
@@ -2143,7 +2183,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
             let (kind, s) = match types[..] {
                 [.., _, last] => (
                     format!(
-                        "{} and `{last}`",
+                        "{} and {last}",
                         types[..types.len() - 1]
                             .iter()
                             .map(|&x| x)
@@ -2161,9 +2201,12 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 self.tcx().sess,
                 span,
                 E0109,
-                "{kind} arguments are not allowed for this type",
+                "{kind} arguments are not allowed on {this_type}",
             );
             err.span_label(last_span, format!("{kind} argument{s} not allowed"));
+            for (_, span) in types_and_spans {
+                err.span_label(span, "not allowed on this");
+            }
             extend(&mut err);
             err.emit();
             emitted = true;

src/test/ui/derives/issue-97343.rs

@@ -1,7 +1,7 @@
 use std::fmt::Debug;
 
 #[derive(Debug)]
-pub struct Irrelevant<Irrelevant> { //~ ERROR type arguments are not allowed for this type
+pub struct Irrelevant<Irrelevant> { //~ ERROR type arguments are not allowed on type parameter
     irrelevant: Irrelevant,
 }
 

src/test/ui/derives/issue-97343.stderr

@@ -1,8 +1,11 @@
-error[E0109]: type arguments are not allowed for this type
+error[E0109]: type arguments are not allowed on type parameter `Irrelevant`
   --> $DIR/issue-97343.rs:4:23
    |
 LL | #[derive(Debug)]
-   |          ----- in this derive macro expansion
+   |          -----
+   |          |
+   |          not allowed on this
+   |          in this derive macro expansion
 LL | pub struct Irrelevant<Irrelevant> {
    |                       ^^^^^^^^^^ type argument not allowed
    |

src/test/ui/error-codes/E0109.stderr

@@ -1,8 +1,10 @@
-error[E0109]: type arguments are not allowed for this type
+error[E0109]: type arguments are not allowed on this type
   --> $DIR/E0109.rs:1:14
    |
 LL | type X = u32<i32>;
-   |              ^^^ type argument not allowed
+   |          --- ^^^ type argument not allowed
+   |          |
+   |          not allowed on this
    |
 help: primitive type `u32` doesn't have type parameters
    |

src/test/ui/error-codes/E0110.stderr

@@ -1,8 +1,10 @@
-error[E0109]: lifetime arguments are not allowed for this type
+error[E0109]: lifetime arguments are not allowed on this type
   --> $DIR/E0110.rs:1:14
    |
 LL | type X = u32<'static>;
-   |              ^^^^^^^ lifetime argument not allowed
+   |          --- ^^^^^^^ lifetime argument not allowed
+   |          |
+   |          not allowed on this
    |
 help: primitive type `u32` doesn't have type parameters
    |

src/test/ui/issues/issue-22706.rs

@@ -1,3 +1,3 @@
 fn is_copy<T: ::std::marker<i32>::Copy>() {}
-//~^ ERROR type arguments are not allowed for this type [E0109]
+//~^ ERROR type arguments are not allowed on module `marker` [E0109]
 fn main() {}

src/test/ui/issues/issue-22706.stderr

@@ -1,8 +1,10 @@
-error[E0109]: type arguments are not allowed for this type
+error[E0109]: type arguments are not allowed on module `marker`
   --> $DIR/issue-22706.rs:1:29
    |
 LL | fn is_copy<T: ::std::marker<i32>::Copy>() {}
-   |                             ^^^ type argument not allowed
+   |                      ------ ^^^ type argument not allowed
+   |                      |
+   |                      not allowed on this
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-57924.rs

@@ -3,7 +3,7 @@ pub struct Gcm<E>(E);
 impl<E> Gcm<E> {
     pub fn crash(e: E) -> Self {
         Self::<E>(e)
-        //~^ ERROR type arguments are not allowed for this type
+        //~^ ERROR type arguments are not allowed on self constructor
     }
 }
 

src/test/ui/issues/issue-57924.stderr

@@ -1,8 +1,10 @@
-error[E0109]: type arguments are not allowed for this type
+error[E0109]: type arguments are not allowed on self constructor
   --> $DIR/issue-57924.rs:5:16
    |
 LL |         Self::<E>(e)
-   |                ^ type argument not allowed
+   |         ----   ^ type argument not allowed
+   |         |
+   |         not allowed on this
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-60989.rs

@@ -10,9 +10,9 @@ impl From<A> for B {
 fn main() {
     let c1 = ();
     c1::<()>;
-    //~^ ERROR type arguments are not allowed for this type
+    //~^ ERROR type arguments are not allowed on local variable
 
     let c1 = A {};
     c1::<dyn Into<B>>;
-    //~^ ERROR type arguments are not allowed for this type
+    //~^ ERROR type arguments are not allowed on local variable
 }