Rollup merge of #36798 - gavinb:fix/36164, r=GuillaumeGomez

Improve error message and snippet for "did you mean `x`"

- Fixes #36164
- Part of #35233

Based on the standalone example https://is.gd/8STXMd posted by @nikomatsakis and using the third formatting option mentioned in #36164 and agreed by @jonathandturner.

Note however this does not address the question of [how to handle an empty or unknown suggestion](#36164 (comment)). @nikomatsakis any suggestions on how best to address that part?

Author: Manishearth

src/librustc_typeck/check/mod.rs

@@ -2959,18 +2959,20 @@ 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 \

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

@@ -11,6 +11,6 @@
 // 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; //~ no field `foo` on type `{integer}`
+    let _ = x.bar; //~ no field `bar` on type `{integer}`
 }

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

@@ -112,7 +112,7 @@ 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; //~ no field `f` on type `fn() {main}`
 
     let cf: *const Foo = &0;
     let _ = cf as *const [u16];

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

@@ -19,7 +19,7 @@ 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`
         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; //~ no field `x` on type `*mut A`
                        //~| 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; //~ no field `y` on type `*mut A`
                        //~| 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); //~ 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`
+    //~^ no field `nonexistent_field` on type `MyStruct`
 }

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

@@ -12,5 +12,5 @@ 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
+    //~^ no field `a` on type `Foo`
 }

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[ //~ no field `create_a_type_error` on type `{integer}`
         ()+() //~ ERROR binary operation `+` cannot be applied
               //   ^ ensure that we typeck the inner expression ^
     ];

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

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