Rollup merge of rust-lang#36128 - gavinb:error_msgs_p2, r=jonathandturner

Update Error format for E0516, E0517, E0518

- E0518 Update error format rust-lang#36111
- E0517 Update error format rust-lang#36109
- E0516 Update error format rust-lang#36108
- Part of rust-lang#35233

r? @jonathandturner

Author: Jonathan Turner

src/librustc/hir/check_attr.rs

@@ -42,7 +42,9 @@ struct CheckAttrVisitor<'a> {
 impl<'a> CheckAttrVisitor<'a> {
     fn check_inline(&self, attr: &ast::Attribute, target: Target) {
         if target != Target::Fn {
-            span_err!(self.sess, attr.span, E0518, "attribute should be applied to function");
+            struct_span_err!(self.sess, attr.span, E0518, "attribute should be applied to function")
+                .span_label(attr.span, &format!("requires a function"))
+                .emit();
         }
     }
 
@@ -56,18 +58,20 @@ impl<'a> CheckAttrVisitor<'a> {
 
         let mut conflicting_reprs = 0;
         for word in words {
+
             let name = match word.name() {
                 Some(word) => word,
                 None => continue,
             };
 
-            let message = match &*name {
+            let (message, label) = match &*name {
                 "C" => {
                     conflicting_reprs += 1;
                     if target != Target::Struct &&
                             target != Target::Union &&
                             target != Target::Enum {
-                        "attribute should be applied to struct, enum or union"
+                                ("attribute should be applied to struct, enum or union",
+                                 "a struct, enum or union")
                     } else {
                         continue
                     }
@@ -77,15 +81,17 @@ impl<'a> CheckAttrVisitor<'a> {
                     // can be used to modify another repr hint
                     if target != Target::Struct &&
                             target != Target::Union {
-                        "attribute should be applied to struct or union"
+                                ("attribute should be applied to struct or union",
+                                 "a struct or union")
                     } else {
                         continue
                     }
                 }
                 "simd" => {
                     conflicting_reprs += 1;
                     if target != Target::Struct {
-                        "attribute should be applied to struct"
+                        ("attribute should be applied to struct",
+                         "a struct")
                     } else {
                         continue
                     }
@@ -95,15 +101,17 @@ impl<'a> CheckAttrVisitor<'a> {
                 "isize" | "usize" => {
                     conflicting_reprs += 1;
                     if target != Target::Enum {
-                        "attribute should be applied to enum"
+                        ("attribute should be applied to enum",
+                         "an enum")
                     } else {
                         continue
                     }
                 }
                 _ => continue,
             };
-
-            span_err!(self.sess, attr.span, E0517, "{}", message);
+            struct_span_err!(self.sess, attr.span, E0517, "{}", message)
+                .span_label(attr.span, &format!("requires {}", label))
+                .emit();
         }
         if conflicting_reprs > 1 {
             span_warn!(self.sess, attr.span, E0566,

src/librustc_typeck/astconv.rs

@@ -1769,8 +1769,11 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
                 }
             }
             hir::TyTypeof(ref _e) => {
-                span_err!(tcx.sess, ast_ty.span, E0516,
-                      "`typeof` is a reserved keyword but unimplemented");
+                struct_span_err!(tcx.sess, ast_ty.span, E0516,
+                                 "`typeof` is a reserved keyword but unimplemented")
+                    .span_label(ast_ty.span, &format!("reserved keyword"))
+                    .emit();
+
                 tcx.types.err
             }
             hir::TyInfer => {

src/test/compile-fail/E0516.rs

@@ -10,4 +10,5 @@
 
 fn main() {
     let x: typeof(92) = 92; //~ ERROR E0516
+                            //~| reserved keyword
 }

src/test/compile-fail/E0517.rs

@@ -9,15 +9,19 @@
 // except according to those terms.
 
 #[repr(C)] //~ ERROR E0517
+           //~| requires a struct, enum or union
 type Foo = u8;
 
 #[repr(packed)] //~ ERROR E0517
+                //~| requires a struct
 enum Foo2 {Bar, Baz}
 
 #[repr(u8)] //~ ERROR E0517
+            //~| requires an enum
 struct Foo3 {bar: bool, baz: bool}
 
 #[repr(C)] //~ ERROR E0517
+           //~| requires a struct, enum or union
 impl Foo3 {
 }
 

src/test/compile-fail/E0518.rs

@@ -9,9 +9,11 @@
 // except according to those terms.
 
 #[inline(always)] //~ ERROR E0518
+                  //~| requires a function
 struct Foo;
 
 #[inline(never)] //~ ERROR E0518
+                 //~| requires a function
 impl Foo {
 }