Emit warnings for misplaced attributes used by some crates

compiler/rustc_passes/src/check_attr.rs

@@ -66,22 +66,24 @@ impl CheckAttrVisitor<'tcx> {
             } else if self.tcx.sess.check_name(attr, sym::marker) {
                 self.check_marker(attr, span, target)
             } else if self.tcx.sess.check_name(attr, sym::target_feature) {
-                self.check_target_feature(attr, span, target)
+                self.check_target_feature(hir_id, attr, span, target)
             } else if self.tcx.sess.check_name(attr, sym::track_caller) {
                 self.check_track_caller(&attr.span, attrs, span, target)
             } else if self.tcx.sess.check_name(attr, sym::doc) {
                 self.check_doc_alias(attr, hir_id, target)
-            } else if self.tcx.sess.check_name(attr, sym::cold) {
-                self.check_cold(&attr, span, target)
-            } else if self.tcx.sess.check_name(attr, sym::link_name) {
-                self.check_link_name(&attr, span, target)
             } else if self.tcx.sess.check_name(attr, sym::no_link) {
                 self.check_no_link(&attr, span, target)
             } else if self.tcx.sess.check_name(attr, sym::export_name) {
                 self.check_export_name(&attr, span, target)
-            } else if self.tcx.sess.check_name(attr, sym::link_section) {
-                self.check_link_section(&attr, span, target)
             } else {
+                // lint-only checks
+                if self.tcx.sess.check_name(attr, sym::cold) {
+                    self.check_cold(hir_id, attr, span, target);
+                } else if self.tcx.sess.check_name(attr, sym::link_name) {
+                    self.check_link_name(hir_id, attr, span, target);
+                } else if self.tcx.sess.check_name(attr, sym::link_section) {
+                    self.check_link_section(hir_id, attr, span, target);
+                }
                 true
             };
         }
@@ -212,10 +214,31 @@ impl CheckAttrVisitor<'tcx> {
     }
 
     /// Checks if the `#[target_feature]` attribute on `item` is valid. Returns `true` if valid.
-    fn check_target_feature(&self, attr: &Attribute, span: &Span, target: Target) -> bool {
+    fn check_target_feature(
+        &self,
+        hir_id: HirId,
+        attr: &Attribute,
+        span: &Span,
+        target: Target,
+    ) -> bool {
         match target {
             Target::Fn
             | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
+            // FIXME: #[target_feature] was previously erroneously allowed on statements and some
+            // crates used this, so only emit a warning.
+            Target::Statement => {
+                self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
+                    lint.build("attribute should be applied to a function")
+                        .warn(
+                            "this was previously accepted by the compiler but is \
+                               being phased out; it will become a hard error in \
+                               a future release!",
+                        )
+                        .span_label(*span, "not a function")
+                        .emit();
+                });
+                true
+            }
             _ => {
                 self.tcx
                     .sess
@@ -288,45 +311,58 @@ impl CheckAttrVisitor<'tcx> {
     }
 
     /// Checks if `#[cold]` is applied to a non-function. Returns `true` if valid.
-    fn check_cold(&self, attr: &Attribute, span: &Span, target: Target) -> bool {
+    fn check_cold(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) {
         match target {
-            Target::Fn | Target::Method(..) | Target::ForeignFn => true,
+            Target::Fn | Target::Method(..) | Target::ForeignFn => {}
             _ => {
-                self.tcx
+                // FIXME: #[cold] was previously allowed on non-functions and some crates used
-                    .sess
+                // this, so only emit a warning.
-                    .struct_span_err(attr.span, "attribute should be applied to a function")
+                self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
+                    lint.build("attribute should be applied to a function")
+                        .warn(
+                            "this was previously accepted by the compiler but is \
+                               being phased out; it will become a hard error in \
+                               a future release!",
+                        )
                         .span_label(*span, "not a function")
                         .emit();
-                false
+                });
             }
         }
     }
 
-    /// Checks if `#[link_name]` is applied to an item other than a foreign function or static. Returns `true` if valid.
+    /// Checks if `#[link_name]` is applied to an item other than a foreign function or static.
-    fn check_link_name(&self, attr: &Attribute, span: &Span, target: Target) -> bool {
+    fn check_link_name(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) {
-        if target == Target::ForeignFn || target == Target::ForeignStatic {
+        match target {
-            true
+            Target::ForeignFn | Target::ForeignStatic => {}
-        } else {
+            _ => {
-            let mut err = self.tcx.sess.struct_span_err(
+                // FIXME: #[cold] was previously allowed on non-functions/statics and some crates
-                attr.span,
+                // used this, so only emit a warning.
-                "attribute should be applied to a foreign function or static",
+                self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
+                    let mut diag =
+                        lint.build("attribute should be applied to a foreign function or static");
+                    diag.warn(
+                        "this was previously accepted by the compiler but is \
+                               being phased out; it will become a hard error in \
+                               a future release!",
                     );
-            err.span_label(*span, "not a foreign function or static");
 
                     // See issue #47725
-            if target == Target::ForeignMod {
+                    if let Target::ForeignMod = target {
                         if let Some(value) = attr.value_str() {
-                    err.span_help(
+                            diag.span_help(
                                 attr.span,
                                 &format!(r#"try `#[link(name = "{}")]` instead"#, value),
                             );
                         } else {
-                    err.span_help(attr.span, r#"try `#[link(name = "...")]` instead"#);
+                            diag.span_help(attr.span, r#"try `#[link(name = "...")]` instead"#);
                         }
                     }
 
-            err.emit();
+                    diag.span_label(*span, "not a foreign function or static");
-            false
+                    diag.emit();
+                });
+            }
         }
     }
 
@@ -362,20 +398,23 @@ impl CheckAttrVisitor<'tcx> {
         }
     }
 
-    /// Checks if `#[link_section]` is applied to a function or static. Returns `true` if valid.
+    /// Checks if `#[link_section]` is applied to a function or static.
-    fn check_link_section(&self, attr: &Attribute, span: &Span, target: Target) -> bool {
+    fn check_link_section(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) {
         match target {
-            Target::Static | Target::Fn | Target::Method(..) => true,
+            Target::Static | Target::Fn | Target::Method(..) => {}
             _ => {
-                self.tcx
+                // FIXME: #[link_section] was previously allowed on non-functions/statics and some
-                    .sess
+                // crates used this, so only emit a warning.
-                    .struct_span_err(
+                self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
-                        attr.span,
+                    lint.build("attribute should be applied to a function or static")
-                        "attribute should be applied to a function or static",
+                        .warn(
+                            "this was previously accepted by the compiler but is \
+                               being phased out; it will become a hard error in \
+                               a future release!",
                         )
                         .span_label(*span, "not a function or static")
                         .emit();
-                false
+                });
             }
         }
     }
@@ -424,7 +463,11 @@ impl CheckAttrVisitor<'tcx> {
                 }
                 sym::simd => {
                     is_simd = true;
-                    if target != Target::Struct { ("a", "struct") } else { continue }
+                    if target != Target::Struct {
+                        ("a", "struct")
+                    } else {
+                        continue;
+                    }
                 }
                 sym::transparent => {
                     is_transparent = true;
@@ -461,7 +504,11 @@ impl CheckAttrVisitor<'tcx> {
                 | sym::isize
                 | sym::usize => {
                     int_reprs += 1;
-                    if target != Target::Enum { ("an", "enum") } else { continue }
+                    if target != Target::Enum {
+                        ("an", "enum")
+                    } else {
+                        continue;
+                    }
                 }
                 _ => continue,
             };

src/test/ui/feature-gate/issue-43106-gating-of-builtin-attrs-error.rs

@@ -64,30 +64,6 @@ mod no_link {
     //~| NOTE not an `extern crate` item
 }
 
-#[cold]
-//~^ ERROR attribute should be applied to a function
-mod cold {
-    //~^ NOTE not a function
-
-    mod inner { #![cold] }
-    //~^ ERROR attribute should be applied to a function
-    //~| NOTE not a function
-
-    #[cold] fn f() { }
-
-    #[cold] struct S;
-    //~^ ERROR attribute should be applied to a function
-    //~| NOTE not a function
-
-    #[cold] type T = S;
-    //~^ ERROR attribute should be applied to a function
-    //~| NOTE not a function
-
-    #[cold] impl S { }
-    //~^ ERROR attribute should be applied to a function
-    //~| NOTE not a function
-}
-
 #[export_name = "2200"]
 //~^ ERROR attribute should be applied to a function or static
 mod export_name {
@@ -112,60 +88,4 @@ mod export_name {
     //~| NOTE not a function or static
 }
 
-#[link_name = "1900"]
-//~^ ERROR attribute should be applied to a foreign function or static
-mod link_name {
-    //~^ NOTE not a foreign function or static
-
-    #[link_name = "1900"]
-    //~^ ERROR attribute should be applied to a foreign function or static
-    //~| HELP try `#[link(name = "1900")]` instead
-    extern { }
-    //~^ NOTE not a foreign function or static
-
-    mod inner { #![link_name="1900"] }
-    //~^ ERROR attribute should be applied to a foreign function or static
-    //~| NOTE not a foreign function or static
-
-    #[link_name = "1900"] fn f() { }
-    //~^ ERROR attribute should be applied to a foreign function or static
-    //~| NOTE not a foreign function or static
-
-    #[link_name = "1900"] struct S;
-    //~^ ERROR attribute should be applied to a foreign function or static
-    //~| NOTE not a foreign function or static
-
-    #[link_name = "1900"] type T = S;
-    //~^ ERROR attribute should be applied to a foreign function or static
-    //~| NOTE not a foreign function or static
-
-    #[link_name = "1900"] impl S { }
-    //~^ ERROR attribute should be applied to a foreign function or static
-    //~| NOTE not a foreign function or static
-}
-
-#[link_section = "1800"]
-//~^ ERROR attribute should be applied to a function or static
-mod link_section {
-    //~^ NOTE not a function or static
-
-    mod inner { #![link_section="1800"] }
-    //~^ ERROR attribute should be applied to a function or static
-    //~| NOTE not a function or static
-
-    #[link_section = "1800"] fn f() { }
-
-    #[link_section = "1800"] struct S;
-    //~^ ERROR attribute should be applied to a function or static
-    //~| NOTE not a function or static
-
-    #[link_section = "1800"] type T = S;
-    //~^ ERROR attribute should be applied to a function or static
-    //~| NOTE not a function or static
-
-    #[link_section = "1800"] impl S { }
-    //~^ ERROR attribute should be applied to a function or static
-    //~| NOTE not a function or static
-}
-
 fn main() {}

src/test/ui/feature-gate/issue-43106-gating-of-builtin-attrs-error.stderr

@@ -38,23 +38,8 @@ LL | |
 LL | | }
    | |_- not an `extern crate` item
 
-error: attribute should be applied to a function
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:67:1
-   |
-LL |   #[cold]
-   |   ^^^^^^^
-LL |
-LL | / mod cold {
-LL | |
-LL | |
-LL | |     mod inner { #![cold] }
-...  |
-LL | |
-LL | | }
-   | |_- not a function
-
 error: attribute should be applied to a function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:91:1
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:67:1
    |
 LL |   #[export_name = "2200"]
    |   ^^^^^^^^^^^^^^^^^^^^^^^
@@ -68,36 +53,6 @@ LL | |
 LL | | }
    | |_- not a function or static
 
-error: attribute should be applied to a foreign function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:115:1
-   |
-LL |   #[link_name = "1900"]
-   |   ^^^^^^^^^^^^^^^^^^^^^
-LL |
-LL | / mod link_name {
-LL | |
-LL | |
-LL | |     #[link_name = "1900"]
-...  |
-LL | |
-LL | | }
-   | |_- not a foreign function or static
-
-error: attribute should be applied to a function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:147:1
-   |
-LL |   #[link_section = "1800"]
-   |   ^^^^^^^^^^^^^^^^^^^^^^^^
-LL |
-LL | / mod link_section {
-LL | |
-LL | |
-LL | |     mod inner { #![link_section="1800"] }
-...  |
-LL | |
-LL | | }
-   | |_- not a function or static
-
 error[E0518]: attribute should be applied to function or closure
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:18:17
    |
@@ -152,123 +107,30 @@ error: attribute should be applied to an `extern crate` item
 LL |     #[no_link] impl S { }
    |     ^^^^^^^^^^ ---------- not an `extern crate` item
 
-error: attribute should be applied to a function
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:72:17
-   |
-LL |     mod inner { #![cold] }
-   |     ------------^^^^^^^^-- not a function
-
-error: attribute should be applied to a function
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:78:5
-   |
-LL |     #[cold] struct S;
-   |     ^^^^^^^ --------- not a function
-
-error: attribute should be applied to a function
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:82:5
-   |
-LL |     #[cold] type T = S;
-   |     ^^^^^^^ ----------- not a function
-
-error: attribute should be applied to a function
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:86:5
-   |
-LL |     #[cold] impl S { }
-   |     ^^^^^^^ ---------- not a function
-
 error: attribute should be applied to a function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:96:17
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:72:17
    |
 LL |     mod inner { #![export_name="2200"] }
    |     ------------^^^^^^^^^^^^^^^^^^^^^^-- not a function or static
 
 error: attribute should be applied to a function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:102:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:78:5
    |
 LL |     #[export_name = "2200"] struct S;
    |     ^^^^^^^^^^^^^^^^^^^^^^^ --------- not a function or static
 
 error: attribute should be applied to a function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:106:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:82:5
    |
 LL |     #[export_name = "2200"] type T = S;
    |     ^^^^^^^^^^^^^^^^^^^^^^^ ----------- not a function or static
 
 error: attribute should be applied to a function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:110:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:86:5
    |
 LL |     #[export_name = "2200"] impl S { }
    |     ^^^^^^^^^^^^^^^^^^^^^^^ ---------- not a function or static
 
-error: attribute should be applied to a foreign function or static
+error: aborting due to 17 previous errors
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:120:5
-   |
-LL |     #[link_name = "1900"]
-   |     ^^^^^^^^^^^^^^^^^^^^^
-...
-LL |     extern { }
-   |     ---------- not a foreign function or static
-   |
-help: try `#[link(name = "1900")]` instead
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:120:5
-   |
-LL |     #[link_name = "1900"]
-   |     ^^^^^^^^^^^^^^^^^^^^^
-
-error: attribute should be applied to a foreign function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:126:17
-   |
-LL |     mod inner { #![link_name="1900"] }
-   |     ------------^^^^^^^^^^^^^^^^^^^^-- not a foreign function or static
-
-error: attribute should be applied to a foreign function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:130:5
-   |
-LL |     #[link_name = "1900"] fn f() { }
-   |     ^^^^^^^^^^^^^^^^^^^^^ ---------- not a foreign function or static
-
-error: attribute should be applied to a foreign function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:134:5
-   |
-LL |     #[link_name = "1900"] struct S;
-   |     ^^^^^^^^^^^^^^^^^^^^^ --------- not a foreign function or static
-
-error: attribute should be applied to a foreign function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:138:5
-   |
-LL |     #[link_name = "1900"] type T = S;
-   |     ^^^^^^^^^^^^^^^^^^^^^ ----------- not a foreign function or static
-
-error: attribute should be applied to a foreign function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:142:5
-   |
-LL |     #[link_name = "1900"] impl S { }
-   |     ^^^^^^^^^^^^^^^^^^^^^ ---------- not a foreign function or static
-
-error: attribute should be applied to a function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:152:17
-   |
-LL |     mod inner { #![link_section="1800"] }
-   |     ------------^^^^^^^^^^^^^^^^^^^^^^^-- not a function or static
-
-error: attribute should be applied to a function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:158:5
-   |
-LL |     #[link_section = "1800"] struct S;
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^ --------- not a function or static
-
-error: attribute should be applied to a function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:162:5
-   |
-LL |     #[link_section = "1800"] type T = S;
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^ ----------- not a function or static
-
-error: attribute should be applied to a function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:166:5
-   |
-LL |     #[link_section = "1800"] impl S { }
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^ ---------- not a function or static
-
-error: aborting due to 34 previous errors
 
 For more information about this error, try `rustc --explain E0518`.

src/test/ui/feature-gate/issue-43106-gating-of-builtin-attrs.rs

@@ -31,14 +31,19 @@
 // occurrences in the source text.
 
 // check-pass
+// ignore-tidy-linelength
 
 #![feature(test, plugin_registrar)]
 #![warn(unused_attributes, unknown_lints)]
+//~^ NOTE the lint level is defined here
+//~| NOTE the lint level is defined here
 
 // Exception, a gated and deprecated attribute.
 
-#![plugin_registrar] //~ WARN unused attribute
+#![plugin_registrar]
+//~^ WARN unused attribute
 //~| WARN use of deprecated attribute
+//~| HELP may be removed in a future compiler version
 
 // UNGATED WHITE-LISTED BUILT-IN ATTRIBUTES
 
@@ -88,12 +93,18 @@
 #![crate_name = "0900"]
 #![crate_type = "bin"] // cannot pass "0800" here
 
-#![crate_id = "10"] //~ WARN use of deprecated attribute
+#![crate_id = "10"]
+//~^ WARN use of deprecated attribute
+//~| HELP remove this attribute
 
 // FIXME(#44232) we should warn that this isn't used.
-#![feature(rust1)] //~ WARN no longer requires an attribute to enable
+#![feature(rust1)]
+//~^ WARN no longer requires an attribute to enable
+//~| NOTE `#[warn(stable_features)]` on by default
 
-#![no_start] //~ WARN use of deprecated attribute
+#![no_start]
+//~^ WARN use of deprecated attribute
+//~| HELP remove this attribute
 
 // (cannot easily gating state of crate-level #[no_main]; but non crate-level is below at "0400")
 #![no_builtins]
@@ -217,24 +228,30 @@ mod macro_export {
 #[plugin_registrar]
 //~^ WARN unused attribute
 //~| WARN use of deprecated attribute
+//~| HELP may be removed in a future compiler version
 mod plugin_registrar {
     mod inner { #![plugin_registrar] }
     //~^ WARN unused attribute
     //~| WARN use of deprecated attribute
+    //~| HELP may be removed in a future compiler version
+    //~| NOTE `#[warn(deprecated)]` on by default
 
     // for `fn f()` case, see gated-plugin_registrar.rs
 
     #[plugin_registrar] struct S;
     //~^ WARN unused attribute
     //~| WARN use of deprecated attribute
+    //~| HELP may be removed in a future compiler version
 
     #[plugin_registrar] type T = S;
     //~^ WARN unused attribute
     //~| WARN use of deprecated attribute
+    //~| HELP may be removed in a future compiler version
 
     #[plugin_registrar] impl S { }
     //~^ WARN unused attribute
     //~| WARN use of deprecated attribute
+    //~| HELP may be removed in a future compiler version
 }
 
 #[main]
@@ -449,6 +466,7 @@ mod reexport_test_harness_main {
 mod macro_escape {
     mod inner { #![macro_escape] }
     //~^ WARN `#[macro_escape]` is a deprecated synonym for `#[macro_use]`
+    //~| HELP try an outer attribute: `#[macro_use]`
 
     #[macro_escape] fn f() { }
     //~^ WARN unused attribute
@@ -505,6 +523,104 @@ mod doc {
     #[doc = "2400"] impl S { }
 }
 
+#[cold]
+//~^ WARN attribute should be applied to a function
+//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+mod cold {
+    //~^ NOTE not a function
+
+    mod inner { #![cold] }
+    //~^ WARN attribute should be applied to a function
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function
+
+    #[cold] fn f() { }
+
+    #[cold] struct S;
+    //~^ WARN attribute should be applied to a function
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function
+
+    #[cold] type T = S;
+    //~^ WARN attribute should be applied to a function
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function
+
+    #[cold] impl S { }
+    //~^ WARN attribute should be applied to a function
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function
+}
+
+#[link_name = "1900"]
+//~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+mod link_name {
+    //~^ NOTE not a foreign function or static
+
+    #[link_name = "1900"]
+    //~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| HELP try `#[link(name = "1900")]` instead
+    extern { }
+    //~^ NOTE not a foreign function or static
+
+    mod inner { #![link_name="1900"] }
+    //~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a foreign function or static
+
+    #[link_name = "1900"] fn f() { }
+    //~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a foreign function or static
+
+    #[link_name = "1900"] struct S;
+    //~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a foreign function or static
+
+    #[link_name = "1900"] type T = S;
+    //~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a foreign function or static
+
+    #[link_name = "1900"] impl S { }
+    //~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a foreign function or static
+}
+
+#[link_section = "1800"]
+//~^ WARN attribute should be applied to a function or static [unused_attributes]
+//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+mod link_section {
+    //~^ NOTE not a function or static
+
+    mod inner { #![link_section="1800"] }
+    //~^ WARN attribute should be applied to a function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function or static
+
+    #[link_section = "1800"] fn f() { }
+
+    #[link_section = "1800"] struct S;
+    //~^ WARN attribute should be applied to a function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function or static
+
+    #[link_section = "1800"] type T = S;
+    //~^ WARN attribute should be applied to a function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function or static
+
+    #[link_section = "1800"] impl S { }
+    //~^ WARN attribute should be applied to a function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function or static
+}
+
+
 // Note that this is a `check-pass` test, so it
 // will never invoke the linker. These are here nonetheless to point
 // out that we allow them at non-crate-level (though I do not know

src/test/ui/issues/issue-47725.rs

@@ -1,8 +1,14 @@
-#[link_name = "foo"] //~ ERROR attribute should be applied to a foreign function or static
+// ignore-tidy-linelength
+#![warn(unused_attributes)] //~ NOTE lint level is defined here
+
+#[link_name = "foo"]
+//~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 struct Foo; //~ NOTE not a foreign function or static
 
 #[link_name = "foobar"]
-//~^ ERROR attribute should be applied to a foreign function or static
+//~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 //~| HELP try `#[link(name = "foobar")]` instead
 extern "C" {
     fn foo() -> u32;
@@ -12,7 +18,8 @@ extern "C" {
 #[link_name]
 //~^ ERROR malformed `link_name` attribute input
 //~| HELP must be of the form
-//~| ERROR attribute should be applied to a foreign function or static
+//~| WARN attribute should be applied to a foreign function or static [unused_attributes]
+//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 //~| HELP try `#[link(name = "...")]` instead
 extern "C" {
     fn bar() -> u32;

src/test/ui/issues/issue-47725.stderr

@@ -1,19 +1,27 @@
 error: malformed `link_name` attribute input
-  --> $DIR/issue-47725.rs:12:1
+  --> $DIR/issue-47725.rs:18:1
    |
 LL | #[link_name]
    | ^^^^^^^^^^^^ help: must be of the form: `#[link_name = "name"]`
 
-error: attribute should be applied to a foreign function or static
+warning: attribute should be applied to a foreign function or static
-  --> $DIR/issue-47725.rs:1:1
+  --> $DIR/issue-47725.rs:4:1
    |
 LL | #[link_name = "foo"]
    | ^^^^^^^^^^^^^^^^^^^^
+...
 LL | struct Foo;
    | ----------- not a foreign function or static
+   |
+note: the lint level is defined here
+  --> $DIR/issue-47725.rs:2:9
+   |
+LL | #![warn(unused_attributes)]
+   |         ^^^^^^^^^^^^^^^^^
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 
-error: attribute should be applied to a foreign function or static
+warning: attribute should be applied to a foreign function or static
-  --> $DIR/issue-47725.rs:4:1
+  --> $DIR/issue-47725.rs:9:1
    |
 LL |   #[link_name = "foobar"]
    |   ^^^^^^^^^^^^^^^^^^^^^^^
@@ -23,14 +31,15 @@ LL | |     fn foo() -> u32;
 LL | | }
    | |_- not a foreign function or static
    |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 help: try `#[link(name = "foobar")]` instead
-  --> $DIR/issue-47725.rs:4:1
+  --> $DIR/issue-47725.rs:9:1
    |
 LL | #[link_name = "foobar"]
    | ^^^^^^^^^^^^^^^^^^^^^^^
 
-error: attribute should be applied to a foreign function or static
+warning: attribute should be applied to a foreign function or static
-  --> $DIR/issue-47725.rs:12:1
+  --> $DIR/issue-47725.rs:18:1
    |
 LL |   #[link_name]
    |   ^^^^^^^^^^^^
@@ -40,11 +49,12 @@ LL | |     fn bar() -> u32;
 LL | | }
    | |_- not a foreign function or static
    |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 help: try `#[link(name = "...")]` instead
-  --> $DIR/issue-47725.rs:12:1
+  --> $DIR/issue-47725.rs:18:1
    |
 LL | #[link_name]
    | ^^^^^^^^^^^^
 
-error: aborting due to 4 previous errors
+error: aborting due to previous error; 3 warnings emitted
 

src/test/ui/issues/issue-54044.rs

@@ -1,7 +1,14 @@
-#[cold] //~ ERROR attribute should be applied to a function
+// ignore-tidy-linelength
+#![deny(unused_attributes)] //~ NOTE lint level is defined here
+
+#[cold]
+//~^ ERROR attribute should be applied to a function
+//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 struct Foo; //~ NOTE not a function
 
 fn main() {
-    #[cold] //~ ERROR attribute should be applied to a function
+    #[cold]
+    //~^ ERROR attribute should be applied to a function
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
     5; //~ NOTE not a function
 }

src/test/ui/issues/issue-54044.stderr

@@ -1,18 +1,29 @@
 error: attribute should be applied to a function
-  --> $DIR/issue-54044.rs:1:1
+  --> $DIR/issue-54044.rs:4:1
    |
 LL | #[cold]
    | ^^^^^^^
+...
 LL | struct Foo;
    | ----------- not a function
+   |
+note: the lint level is defined here
+  --> $DIR/issue-54044.rs:2:9
+   |
+LL | #![deny(unused_attributes)]
+   |         ^^^^^^^^^^^^^^^^^
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 
 error: attribute should be applied to a function
-  --> $DIR/issue-54044.rs:5:5
+  --> $DIR/issue-54044.rs:10:5
    |
 LL |     #[cold]
    |     ^^^^^^^
+...
 LL |     5;
    |     - not a function
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 
 error: aborting due to 2 previous errors
 

src/test/ui/macros/issue-68060.rs

@@ -4,10 +4,13 @@ fn main() {
             #[target_feature(enable = "")]
             //~^ ERROR: attribute should be applied to a function
             //~| ERROR: the feature named `` is not valid for this target
+            //~| NOTE: `` is not valid for this target
             #[track_caller]
             //~^ ERROR: attribute should be applied to function [E0739]
             //~| ERROR: `#[track_caller]` requires Rust ABI [E0737]
             |_| (),
+            //~^ NOTE: not a function
+            //~| NOTE: not a function
         )
         .next();
 }

src/test/ui/macros/issue-68060.stderr

@@ -8,7 +8,7 @@ LL |             |_| (),
    |             ------ not a function
 
 error[E0739]: attribute should be applied to function
-  --> $DIR/issue-68060.rs:7:13
+  --> $DIR/issue-68060.rs:8:13
    |
 LL |             #[track_caller]
    |             ^^^^^^^^^^^^^^^

src/test/ui/target-feature/invalid-attribute.rs

@@ -13,6 +13,7 @@
 // ignore-sparc64
 
 #![feature(target_feature)]
+#![warn(unused_attributes)]
 
 #[target_feature = "+sse2"]
 //~^ ERROR malformed `target_feature` attribute
@@ -48,17 +49,20 @@ struct Foo;
 
 #[target_feature(enable = "sse2")]
 //~^ ERROR attribute should be applied to a function
-enum Bar { }
+enum Bar {}
 //~^ NOTE not a function
 
 #[target_feature(enable = "sse2")]
 //~^ ERROR attribute should be applied to a function
-union Qux { f1: u16, f2: u16 }
+union Qux {
 //~^ NOTE not a function
+    f1: u16,
+    f2: u16,
+}
 
 #[target_feature(enable = "sse2")]
 //~^ ERROR attribute should be applied to a function
-trait Baz { }
+trait Baz {}
 //~^ NOTE not a function
 
 #[inline(always)]

src/test/ui/target-feature/invalid-attribute.stderr

@@ -1,29 +1,29 @@
 error: malformed `target_feature` attribute input
-  --> $DIR/invalid-attribute.rs:17:1
+  --> $DIR/invalid-attribute.rs:18:1
    |
 LL | #[target_feature = "+sse2"]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#[target_feature(enable = "name")]`
 
 error: the feature named `foo` is not valid for this target
-  --> $DIR/invalid-attribute.rs:19:18
+  --> $DIR/invalid-attribute.rs:20:18
    |
 LL | #[target_feature(enable = "foo")]
    |                  ^^^^^^^^^^^^^^ `foo` is not valid for this target
 
 error: malformed `target_feature` attribute input
-  --> $DIR/invalid-attribute.rs:22:18
+  --> $DIR/invalid-attribute.rs:23:18
    |
 LL | #[target_feature(bar)]
    |                  ^^^ help: must be of the form: `enable = ".."`
 
 error: malformed `target_feature` attribute input
-  --> $DIR/invalid-attribute.rs:24:18
+  --> $DIR/invalid-attribute.rs:25:18
    |
 LL | #[target_feature(disable = "baz")]
    |                  ^^^^^^^^^^^^^^^ help: must be of the form: `enable = ".."`
 
 error[E0658]: `#[target_feature(..)]` can only be applied to `unsafe` functions
-  --> $DIR/invalid-attribute.rs:28:1
+  --> $DIR/invalid-attribute.rs:29:1
    |
 LL | #[target_feature(enable = "sse2")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -35,7 +35,7 @@ LL | fn bar() {}
    = help: add `#![feature(target_feature_11)]` to the crate attributes to enable
 
 error: attribute should be applied to a function
-  --> $DIR/invalid-attribute.rs:34:1
+  --> $DIR/invalid-attribute.rs:35:1
    |
 LL | #[target_feature(enable = "sse2")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -44,7 +44,7 @@ LL | mod another {}
    | -------------- not a function
 
 error: attribute should be applied to a function
-  --> $DIR/invalid-attribute.rs:39:1
+  --> $DIR/invalid-attribute.rs:40:1
    |
 LL | #[target_feature(enable = "sse2")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -53,7 +53,7 @@ LL | const FOO: usize = 7;
    | --------------------- not a function
 
 error: attribute should be applied to a function
-  --> $DIR/invalid-attribute.rs:44:1
+  --> $DIR/invalid-attribute.rs:45:1
    |
 LL | #[target_feature(enable = "sse2")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -62,40 +62,44 @@ LL | struct Foo;
    | ----------- not a function
 
 error: attribute should be applied to a function
-  --> $DIR/invalid-attribute.rs:49:1
+  --> $DIR/invalid-attribute.rs:50:1
    |
 LL | #[target_feature(enable = "sse2")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 LL |
-LL | enum Bar { }
+LL | enum Bar {}
+   | ----------- not a function
+
+error: attribute should be applied to a function
+  --> $DIR/invalid-attribute.rs:55:1
+   |
+LL |   #[target_feature(enable = "sse2")]
+   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |
+LL | / union Qux {
+LL | |
+LL | |     f1: u16,
+LL | |     f2: u16,
+LL | | }
+   | |_- not a function
+
+error: attribute should be applied to a function
+  --> $DIR/invalid-attribute.rs:63:1
+   |
+LL | #[target_feature(enable = "sse2")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |
+LL | trait Baz {}
    | ------------ not a function
 
-error: attribute should be applied to a function
-  --> $DIR/invalid-attribute.rs:54:1
-   |
-LL | #[target_feature(enable = "sse2")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-LL |
-LL | union Qux { f1: u16, f2: u16 }
-   | ------------------------------ not a function
-
-error: attribute should be applied to a function
-  --> $DIR/invalid-attribute.rs:59:1
-   |
-LL | #[target_feature(enable = "sse2")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-LL |
-LL | trait Baz { }
-   | ------------- not a function
-
 error: cannot use `#[inline(always)]` with `#[target_feature]`
-  --> $DIR/invalid-attribute.rs:64:1
+  --> $DIR/invalid-attribute.rs:68:1
    |
 LL | #[inline(always)]
    | ^^^^^^^^^^^^^^^^^
 
 error: attribute should be applied to a function
-  --> $DIR/invalid-attribute.rs:82:5
+  --> $DIR/invalid-attribute.rs:86:5
    |
 LL |       #[target_feature(enable = "sse2")]
    |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -107,7 +111,7 @@ LL | |     }
    | |_____- not a function
 
 error: attribute should be applied to a function
-  --> $DIR/invalid-attribute.rs:90:5
+  --> $DIR/invalid-attribute.rs:94:5
    |
 LL |     #[target_feature(enable = "sse2")]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -116,7 +120,7 @@ LL |     || {};
    |     ----- not a function
 
 error[E0658]: `#[target_feature(..)]` can only be applied to `unsafe` functions
-  --> $DIR/invalid-attribute.rs:74:5
+  --> $DIR/invalid-attribute.rs:78:5
    |
 LL |     #[target_feature(enable = "sse2")]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^