Add context to E0084, E00517, E0518

Show both the attribute and the item

src/librustc/hir/check_attr.rs

@@ -47,27 +47,27 @@ struct CheckAttrVisitor<'a> {
 
 impl<'a> CheckAttrVisitor<'a> {
     /// Check any attribute.
-    fn check_attribute(&self, attr: &ast::Attribute, target: Target) {
+    fn check_attribute(&self, attr: &ast::Attribute, item: &ast::Item, target: Target) {
         if let Some(name) = attr.name() {
             match &*name.as_str() {
-                "inline" => self.check_inline(attr, target),
-                "repr" => self.check_repr(attr, target),
+                "inline" => self.check_inline(attr, item, target),
+                "repr" => self.check_repr(attr, item, target),
                 _ => (),
             }
         }
     }
 
     /// Check if an `#[inline]` is applied to a function.
-    fn check_inline(&self, attr: &ast::Attribute, target: Target) {
+    fn check_inline(&self, attr: &ast::Attribute, item: &ast::Item, target: Target) {
         if target != Target::Fn {
             struct_span_err!(self.sess, attr.span, E0518, "attribute should be applied to function")
-                .span_label(attr.span, "requires a function")
+                .span_label(item.span, "not a function")
                 .emit();
         }
     }
 
     /// Check if an `#[repr]` attr is valid.
-    fn check_repr(&self, attr: &ast::Attribute, target: Target) {
+    fn check_repr(&self, attr: &ast::Attribute, item: &ast::Item, target: Target) {
         let words = match attr.meta_item_list() {
             Some(words) => words,
             None => {
@@ -139,7 +139,7 @@ impl<'a> CheckAttrVisitor<'a> {
                 _ => continue,
             };
             struct_span_err!(self.sess, attr.span, E0517, "{}", message)
-                .span_label(attr.span, format!("requires {}", label))
+                .span_label(item.span, format!("not {}", label))
                 .emit();
         }
         if conflicting_reprs > 1 {
@@ -153,7 +153,7 @@ impl<'a> Visitor<'a> for CheckAttrVisitor<'a> {
     fn visit_item(&mut self, item: &'a ast::Item) {
         let target = Target::from_item(item);
         for attr in &item.attrs {
-            self.check_attribute(attr, target);
+            self.check_attribute(attr, item, target);
         }
         visit::walk_item(self, item);
     }

src/librustc_typeck/check/mod.rs

@@ -117,6 +117,7 @@ use std::mem::replace;
 use std::ops::{self, Deref};
 use syntax::abi::Abi;
 use syntax::ast;
+use syntax::attr;
 use syntax::codemap::{self, original_sp, Spanned};
 use syntax::feature_gate::{GateIssue, emit_feature_err};
 use syntax::ptr::P;
@@ -1561,12 +1562,15 @@ pub fn check_enum<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     let def = tcx.adt_def(def_id);
     def.destructor(tcx); // force the destructor to be evaluated
 
-    if vs.is_empty() && tcx.has_attr(def_id, "repr") {
-        struct_span_err!(
-            tcx.sess, sp, E0084,
-            "unsupported representation for zero-variant enum")
-            .span_label(sp, "unsupported enum representation")
-            .emit();
+    if vs.is_empty() {
+        let attributes = tcx.get_attrs(def_id);
+        if let Some(attr) = attr::find_by_name(&attributes, "repr") {
+            struct_span_err!(
+                tcx.sess, attr.span, E0084,
+                "unsupported representation for zero-variant enum")
+                .span_label(sp, "zero-variant enum")
+                .emit();
+        }
     }
 
     let repr_type_ty = def.repr.discr_type().to_ty(tcx);

src/test/compile-fail/E0084.rs

@@ -8,10 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#[repr(i32)]
-enum Foo {}
-//~^ ERROR E0084
-//~| unsupported enum representation
+#[repr(i32)] //~ ERROR E0084
+enum Foo {} //~ zero-variant enum
 
 fn main() {
 }

src/test/compile-fail/E0517.rs

@@ -9,20 +9,16 @@
 // except according to those terms.
 
 #[repr(C)] //~ ERROR E0517
-           //~| requires a struct, enum or union
-type Foo = u8;
+type Foo = u8; //~ not a struct, enum or union
 
 #[repr(packed)] //~ ERROR E0517
-                //~| requires a struct
-enum Foo2 {Bar, Baz}
+enum Foo2 {Bar, Baz} //~ not a struct
 
 #[repr(u8)] //~ ERROR E0517
-            //~| requires an enum
-struct Foo3 {bar: bool, baz: bool}
+struct Foo3 {bar: bool, baz: bool} //~ not an enum
 
 #[repr(C)] //~ ERROR E0517
-           //~| requires a struct, enum or union
-impl Foo3 {
+impl Foo3 { //~ not a struct, enum or union
 }
 
 fn main() {

src/test/compile-fail/E0518.rs

@@ -9,12 +9,10 @@
 // except according to those terms.
 
 #[inline(always)] //~ ERROR E0518
-                  //~| requires a function
-struct Foo;
+struct Foo;       //~ not a function
 
 #[inline(never)] //~ ERROR E0518
-                 //~| requires a function
-impl Foo {
+impl Foo {       //~ not a function
 }
 
 fn main() {

src/test/compile-fail/attr-usage-inline.rs

@@ -14,6 +14,6 @@
 fn f() {}
 
 #[inline] //~ ERROR: attribute should be applied to function
-struct S;
+struct S; //~ not a function
 
 fn main() {}

src/test/compile-fail/attr-usage-repr.rs

@@ -13,7 +13,7 @@
 #![feature(repr_simd)]
 
 #[repr(C)] //~ ERROR: attribute should be applied to struct, enum or union
-fn f() {}
+fn f() {}  //~ not a struct, enum or union
 
 #[repr(C)]
 struct SExtern(f64, f64);
@@ -25,19 +25,19 @@ struct SPacked(f64, f64);
 struct SSimd(f64, f64);
 
 #[repr(i8)] //~ ERROR: attribute should be applied to enum
-struct SInt(f64, f64);
+struct SInt(f64, f64); //~ not an enum
 
 #[repr(C)]
 enum EExtern { A, B }
 
 #[repr(align(8))] //~ ERROR: attribute should be applied to struct
-enum EAlign { A, B }
+enum EAlign { A, B } // not a struct
 
 #[repr(packed)] //~ ERROR: attribute should be applied to struct
-enum EPacked { A, B }
+enum EPacked { A, B } // not a struct
 
 #[repr(simd)] //~ ERROR: attribute should be applied to struct
-enum ESimd { A, B }
+enum ESimd { A, B } // not a struct
 
 #[repr(i8)]
 enum EInt { A, B }

src/test/compile-fail/feature-gate/issue-43106-gating-of-inline.rs

@@ -21,17 +21,28 @@
 #[inline = "2100"]
 //~^ ERROR attribute should be applied to function
 mod inline {
-    mod inner { #![inline="2100"] }
-    //~^ ERROR attribute should be applied to function
+//~^ not a function
+    mod inner {
+    //~^ not a function
+        #![inline="2100"]
+        //~^ ERROR attribute should be applied to function
+    }
 
-    #[inline = "2100"] fn f() { }
+    #[inline = "2100"]
+    fn f() { }
 
-    #[inline = "2100"] struct S;
+    #[inline = "2100"]
     //~^ ERROR attribute should be applied to function
+    struct S;
+    //~^ not a function
 
-    #[inline = "2100"] type T = S;
+    #[inline = "2100"]
     //~^ ERROR attribute should be applied to function
+    type T = S;
+    //~^ not a function
 
-    #[inline = "2100"] impl S { }
+    #[inline = "2100"]
     //~^ ERROR attribute should be applied to function
+    impl S { }
+    //~^ not a function
 }