improve snippet for "did you mean x"

r? @nikomatsakis
cc @jonathandturner

Fixes #36164

Author: 0xmohit

src/librustc_typeck/check/mod.rs

@@ -2959,24 +2959,27 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 .emit();
             self.tcx().types.err
         } else {
-            let mut err = self.type_error_struct(expr.span, |actual| {
-                format!("attempted access of field `{}` on type `{}`, \
-                         but no field with that name was found",
+            let mut err = self.type_error_struct(field.span, |actual| {
+                format!("no field `{}` on type `{}`",
                         field.node, actual)
             }, expr_t);
             match expr_t.sty {
                 ty::TyAdt(def, _) if !def.is_enum() => {
                     if let Some(suggested_field_name) =
                         Self::suggest_field_name(def.struct_variant(), field, vec![]) {
-                        err.span_help(field.span,
-                                      &format!("did you mean `{}`?", suggested_field_name));
-                    };
+                        err.span_label(field.span,
+                                       &format!("did you mean `{}`?", suggested_field_name));
+                    } else {
+                        err.span_label(field.span, &format!("unknown field"));
+                    }
                 }
                 ty::TyRawPtr(..) => {
                     err.note(&format!("`{0}` is a native pointer; perhaps you need to deref with \
                                       `(*{0}).{1}`", pprust::expr_to_string(base), field.node));
                 }
-                _ => {}
+                _ => {
+                    err.span_label(field.span, &format!("unknown field"));
+                }
             }
             err.emit();
             self.tcx().types.err

src/test/compile-fail/attempted-access-non-fatal.rs

@@ -11,6 +11,8 @@
 // Check that bogus field access is non-fatal
 fn main() {
     let x = 0;
-    let _ = x.foo; //~ ERROR attempted access of field
-    let _ = x.bar; //~ ERROR attempted access of field
+    let _ = x.foo; //~ ERROR no field `foo` on type
+                   //~| NOTE unknown field
+    let _ = x.bar; //~ ERROR no field `bar` on type
+                   //~| NOTE unknown field
 }

src/test/compile-fail/cast-rfc0401.rs

@@ -112,7 +112,8 @@ fn main()
     //~| NOTE required for the cast to the object type `Foo`
 
     // check no error cascade
-    let _ = main.f as *const u32; //~ ERROR attempted access of field
+    let _ = main.f as *const u32; //~ ERROR no field `f` on type `fn() {main}`
+                                  //~| NOTE unknown field
 
     let cf: *const Foo = &0;
     let _ = cf as *const [u16];

src/test/compile-fail/derived-errors/issue-30580.rs

@@ -19,7 +19,8 @@ impl<'a, 'tcx> Pass<'a, 'tcx>
     pub fn tcx(&self) -> &'a &'tcx () { self.1 }
     fn lol(&mut self, b: &Foo)
     {
-        b.c; //~ ERROR no field with that name was found
+        b.c; //~ ERROR no field `c` on type `&Foo`
+             //~| unknown field
         self.tcx();
     }
 }

src/test/compile-fail/issue-11004.rs

@@ -14,9 +14,9 @@ struct A { x: i32, y: f64 }
 
 #[cfg(not(works))]
 unsafe fn access(n:*mut A) -> (i32, f64) {
-    let x : i32 = n.x; //~ ERROR attempted access of field `x`
+    let x : i32 = n.x; //~ ERROR no field `x`
                        //~| NOTE `n` is a native pointer; perhaps you need to deref with `(*n).x`
-    let y : f64 = n.y; //~ ERROR attempted access of field `y`
+    let y : f64 = n.y; //~ ERROR no field `y`
                        //~| NOTE `n` is a native pointer; perhaps you need to deref with `(*n).y`
     (x, y)
 }

src/test/compile-fail/issue-14721.rs

@@ -10,6 +10,5 @@
 
 fn main() {
     let foo = "str";
-    println!("{}", foo.desc); //~ ERROR attempted access of field `desc` on type `&str`,
-                              //        but no field with that name was found
+    println!("{}", foo.desc); //~ ERROR no field `desc` on type `&str`
 }

src/test/compile-fail/issue-19244-2.rs

@@ -13,5 +13,5 @@ const STRUCT: MyStruct = MyStruct { field: 42 };
 
 fn main() {
     let a: [isize; STRUCT.nonexistent_field];
-    //~^ ERROR attempted access of field `nonexistent_field`
+    //~^ ERROR no field `nonexistent_field`
 }

src/test/compile-fail/issue-23253.rs

@@ -12,5 +12,6 @@ enum Foo { Bar }
 
 fn main() {
     Foo::Bar.a;
-    //~^ ERROR: attempted access of field `a` on type `Foo`, but no field with that name was found
+    //~^ ERROR: no field `a` on type `Foo`
+    //~| NOTE unknown field
 }

src/test/compile-fail/issue-24363.rs

@@ -9,7 +9,7 @@
 // except according to those terms.
 
 fn main() {
-    1.create_a_type_error[ //~ ERROR attempted access of field
+    1.create_a_type_error[ //~ ERROR no field `create_a_type_error`
         ()+() //~ ERROR binary operation `+` cannot be applied
               //   ^ ensure that we typeck the inner expression ^
     ];

src/test/compile-fail/issue-24365.rs

@@ -17,13 +17,17 @@ pub enum Foo {
 }
 
 fn test(a: Foo) {
-    println!("{}", a.b); //~ ERROR attempted access of field
+    println!("{}", a.b); //~ ERROR no field `b` on type `Foo`
+                         //~| NOTE unknown field
+                         //~| NOTE in this expansion
 }
 
 fn main() {
     let x = Attribute::Code {
         attr_name_idx: 42,
     };
-    let z = (&x).attr_name_idx; //~ ERROR attempted access of field
-    let y = x.attr_name_idx; //~ ERROR attempted access of field
+    let z = (&x).attr_name_idx; //~ ERROR no field `attr_name_idx` on type `&Attribute`
+                                //~| NOTE unknown field
+    let y = x.attr_name_idx; //~ ERROR no field `attr_name_idx` on type `Attribute`
+                             //~| NOTE unknown field
 }