When finding item gated behind a cfg flag, point at it

compiler/rustc_resolve/messages.ftl

@@ -232,6 +232,8 @@ resolve_is_private =
 resolve_item_was_behind_feature =
     the item is gated behind the `{$feature}` feature
 
+resolve_item_was_cfg_out = the item is gated here
+
 resolve_items_in_traits_are_not_importable =
     items in traits are not importable
 

compiler/rustc_resolve/src/diagnostics.rs

@@ -2530,7 +2530,13 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                 && let NestedMetaItem::MetaItem(meta_item) = &nested[0]
                 && let MetaItemKind::NameValue(feature_name) = &meta_item.kind
             {
-                let note = errors::ItemWasBehindFeature { feature: feature_name.symbol };
+                let note = errors::ItemWasBehindFeature {
+                    feature: feature_name.symbol,
+                    span: meta_item.span,
+                };
+                err.subdiagnostic(note);
+            } else {
+                let note = errors::ItemWasCfgOut { span: cfg.span };
                 err.subdiagnostic(note);
             }
         }

compiler/rustc_resolve/src/errors.rs

@@ -1228,6 +1228,15 @@ pub(crate) struct FoundItemConfigureOut {
 #[note(resolve_item_was_behind_feature)]
 pub(crate) struct ItemWasBehindFeature {
     pub(crate) feature: Symbol,
+    #[primary_span]
+    pub(crate) span: Span,
+}
+
+#[derive(Subdiagnostic)]
+#[note(resolve_item_was_cfg_out)]
+pub(crate) struct ItemWasCfgOut {
+    #[primary_span]
+    pub(crate) span: Span,
 }
 
 #[derive(Diagnostic)]

tests/ui/cfg/diagnostics-cross-crate.rs

@@ -11,12 +11,14 @@ fn main() {
     cfged_out::inner::uwu(); //~ ERROR cannot find function
     //~^ NOTE found an item that was configured out
     //~| NOTE not found in `cfged_out::inner`
+    //~| NOTE the item is gated here
 
     // The module isn't found - we would like to get a diagnostic, but currently don't due to
     // the awkward way the resolver diagnostics are currently implemented.
     cfged_out::inner::doesnt_exist::hello(); //~ ERROR failed to resolve
     //~^ NOTE could not find `doesnt_exist` in `inner`
     //~| NOTE found an item that was configured out
+    //~| NOTE the item is gated here
 
     // It should find the one in the right module, not the wrong one.
     cfged_out::inner::right::meow(); //~ ERROR cannot find function
@@ -28,4 +30,5 @@ fn main() {
     cfged_out::vanished(); //~ ERROR cannot find function
     //~^ NOTE found an item that was configured out
     //~| NOTE not found in `cfged_out`
+    //~| NOTE the item is gated here
 }

tests/ui/cfg/diagnostics-cross-crate.stderr

@@ -1,5 +1,5 @@
 error[E0433]: failed to resolve: could not find `doesnt_exist` in `inner`
-  --> $DIR/diagnostics-cross-crate.rs:17:23
+  --> $DIR/diagnostics-cross-crate.rs:18:23
    |
 LL |     cfged_out::inner::doesnt_exist::hello();
    |                       ^^^^^^^^^^^^ could not find `doesnt_exist` in `inner`
@@ -9,6 +9,11 @@ note: found an item that was configured out
    |
 LL |     pub mod doesnt_exist {
    |             ^^^^^^^^^^^^
+note: the item is gated here
+  --> $DIR/auxiliary/cfged_out.rs:5:5
+   |
+LL |     #[cfg(FALSE)]
+   |     ^^^^^^^^^^^^^
 
 error[E0425]: cannot find function `uwu` in crate `cfged_out`
   --> $DIR/diagnostics-cross-crate.rs:7:16
@@ -27,9 +32,14 @@ note: found an item that was configured out
    |
 LL |     pub fn uwu() {}
    |            ^^^
+note: the item is gated here
+  --> $DIR/auxiliary/cfged_out.rs:2:5
+   |
+LL |     #[cfg(FALSE)]
+   |     ^^^^^^^^^^^^^
 
 error[E0425]: cannot find function `meow` in module `cfged_out::inner::right`
-  --> $DIR/diagnostics-cross-crate.rs:22:30
+  --> $DIR/diagnostics-cross-crate.rs:24:30
    |
 LL |     cfged_out::inner::right::meow();
    |                              ^^^^ not found in `cfged_out::inner::right`
@@ -39,10 +49,14 @@ note: found an item that was configured out
    |
 LL |         pub fn meow() {}
    |                ^^^^
-   = note: the item is gated behind the `what-a-cool-feature` feature
+note: the item is gated behind the `what-a-cool-feature` feature
+  --> $DIR/auxiliary/cfged_out.rs:16:15
+   |
+LL |         #[cfg(feature = "what-a-cool-feature")]
+   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0425]: cannot find function `vanished` in crate `cfged_out`
-  --> $DIR/diagnostics-cross-crate.rs:28:16
+  --> $DIR/diagnostics-cross-crate.rs:30:16
    |
 LL |     cfged_out::vanished();
    |                ^^^^^^^^ not found in `cfged_out`
@@ -52,6 +66,11 @@ note: found an item that was configured out
    |
 LL | pub fn vanished() {}
    |        ^^^^^^^^
+note: the item is gated here
+  --> $DIR/auxiliary/cfged_out.rs:21:1
+   |
+LL | #[cfg(i_dont_exist_and_you_can_do_nothing_about_it)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 5 previous errors
 

tests/ui/cfg/diagnostics-reexport.rs

@@ -4,7 +4,7 @@ pub mod inner {
         pub fn uwu() {}
     }
 
-    #[cfg(FALSE)]
+    #[cfg(FALSE)] //~ NOTE the item is gated here
     pub use super::uwu;
     //~^ NOTE found an item that was configured out
 }
@@ -14,7 +14,7 @@ pub use a::x;
 //~| NOTE no `x` in `a`
 
 mod a {
-    #[cfg(FALSE)]
+    #[cfg(FALSE)] //~ NOTE the item is gated here
     pub fn x() {}
     //~^ NOTE found an item that was configured out
 }
@@ -25,10 +25,10 @@ pub use b::{x, y};
 //~| NOTE no `y` in `b`
 
 mod b {
-    #[cfg(FALSE)]
+    #[cfg(FALSE)] //~ NOTE the item is gated here
     pub fn x() {}
     //~^ NOTE found an item that was configured out
-    #[cfg(FALSE)]
+    #[cfg(FALSE)] //~ NOTE the item is gated here
     pub fn y() {}
     //~^ NOTE found an item that was configured out
 }

tests/ui/cfg/diagnostics-reexport.stderr

@@ -9,6 +9,11 @@ note: found an item that was configured out
    |
 LL |     pub fn x() {}
    |            ^
+note: the item is gated here
+  --> $DIR/diagnostics-reexport.rs:17:5
+   |
+LL |     #[cfg(FALSE)]
+   |     ^^^^^^^^^^^^^
 
 error[E0432]: unresolved imports `b::x`, `b::y`
   --> $DIR/diagnostics-reexport.rs:22:13
@@ -23,11 +28,21 @@ note: found an item that was configured out
    |
 LL |     pub fn x() {}
    |            ^
+note: the item is gated here
+  --> $DIR/diagnostics-reexport.rs:28:5
+   |
+LL |     #[cfg(FALSE)]
+   |     ^^^^^^^^^^^^^
 note: found an item that was configured out
   --> $DIR/diagnostics-reexport.rs:32:12
    |
 LL |     pub fn y() {}
    |            ^
+note: the item is gated here
+  --> $DIR/diagnostics-reexport.rs:31:5
+   |
+LL |     #[cfg(FALSE)]
+   |     ^^^^^^^^^^^^^
 
 error[E0425]: cannot find function `uwu` in module `inner`
   --> $DIR/diagnostics-reexport.rs:38:12
@@ -40,6 +55,11 @@ note: found an item that was configured out
    |
 LL |     pub use super::uwu;
    |                    ^^^
+note: the item is gated here
+  --> $DIR/diagnostics-reexport.rs:7:5
+   |
+LL |     #[cfg(FALSE)]
+   |     ^^^^^^^^^^^^^
 
 error: aborting due to 3 previous errors
 

tests/ui/cfg/diagnostics-same-crate.rs

@@ -1,11 +1,13 @@
 #![allow(unexpected_cfgs)] // since we want to recognize them as unexpected
 
 pub mod inner {
-    #[cfg(FALSE)]
+    #[cfg(FALSE)] //~ NOTE the item is gated here
     pub fn uwu() {}
     //~^ NOTE found an item that was configured out
 
-    #[cfg(FALSE)]
+    #[cfg(FALSE)] //~ NOTE the item is gated here
+    //~^ NOTE the item is gated here
+    //~| NOTE the item is gated here
     pub mod doesnt_exist {
         //~^ NOTE found an item that was configured out
         //~| NOTE found an item that was configured out
@@ -20,7 +22,7 @@ pub mod inner {
     }
 
     pub mod right {
-        #[cfg(feature = "what-a-cool-feature")]
+        #[cfg(feature = "what-a-cool-feature")] //~ NOTE the item is gated behind the `what-a-cool-feature` feature
         pub fn meow() {}
         //~^ NOTE found an item that was configured out
     }
@@ -55,7 +57,6 @@ fn main() {
     // It should find the one in the right module, not the wrong one.
     inner::right::meow(); //~ ERROR cannot find function
     //~| NOTE not found in `inner::right
-    //~| NOTE the item is gated behind the `what-a-cool-feature` feature
 
     // Exists in the crate root - we would generally want a diagnostic,
     // but currently don't have one.

tests/ui/cfg/diagnostics-same-crate.stderr

@@ -1,41 +1,56 @@
 error[E0432]: unresolved import `super::inner::doesnt_exist`
-  --> $DIR/diagnostics-same-crate.rs:30:9
+  --> $DIR/diagnostics-same-crate.rs:32:9
    |
 LL |     use super::inner::doesnt_exist;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ no `doesnt_exist` in `inner`
    |
 note: found an item that was configured out
-  --> $DIR/diagnostics-same-crate.rs:9:13
+  --> $DIR/diagnostics-same-crate.rs:11:13
    |
 LL |     pub mod doesnt_exist {
    |             ^^^^^^^^^^^^
+note: the item is gated here
+  --> $DIR/diagnostics-same-crate.rs:8:5
+   |
+LL |     #[cfg(FALSE)]
+   |     ^^^^^^^^^^^^^
 
 error[E0432]: unresolved import `super::inner::doesnt_exist`
-  --> $DIR/diagnostics-same-crate.rs:33:23
+  --> $DIR/diagnostics-same-crate.rs:35:23
    |
 LL |     use super::inner::doesnt_exist::hi;
    |                       ^^^^^^^^^^^^ could not find `doesnt_exist` in `inner`
    |
 note: found an item that was configured out
-  --> $DIR/diagnostics-same-crate.rs:9:13
+  --> $DIR/diagnostics-same-crate.rs:11:13
    |
 LL |     pub mod doesnt_exist {
    |             ^^^^^^^^^^^^
+note: the item is gated here
+  --> $DIR/diagnostics-same-crate.rs:8:5
+   |
+LL |     #[cfg(FALSE)]
+   |     ^^^^^^^^^^^^^
 
 error[E0433]: failed to resolve: could not find `doesnt_exist` in `inner`
-  --> $DIR/diagnostics-same-crate.rs:52:12
+  --> $DIR/diagnostics-same-crate.rs:54:12
    |
 LL |     inner::doesnt_exist::hello();
    |            ^^^^^^^^^^^^ could not find `doesnt_exist` in `inner`
    |
 note: found an item that was configured out
-  --> $DIR/diagnostics-same-crate.rs:9:13
+  --> $DIR/diagnostics-same-crate.rs:11:13
    |
 LL |     pub mod doesnt_exist {
    |             ^^^^^^^^^^^^
+note: the item is gated here
+  --> $DIR/diagnostics-same-crate.rs:8:5
+   |
+LL |     #[cfg(FALSE)]
+   |     ^^^^^^^^^^^^^
 
 error[E0425]: cannot find function `uwu` in module `inner`
-  --> $DIR/diagnostics-same-crate.rs:47:12
+  --> $DIR/diagnostics-same-crate.rs:49:12
    |
 LL |     inner::uwu();
    |            ^^^ not found in `inner`
@@ -45,28 +60,37 @@ note: found an item that was configured out
    |
 LL |     pub fn uwu() {}
    |            ^^^
+note: the item is gated here
+  --> $DIR/diagnostics-same-crate.rs:4:5
+   |
+LL |     #[cfg(FALSE)]
+   |     ^^^^^^^^^^^^^
 
 error[E0425]: cannot find function `meow` in module `inner::right`
-  --> $DIR/diagnostics-same-crate.rs:56:19
+  --> $DIR/diagnostics-same-crate.rs:58:19
    |
 LL |     inner::right::meow();
    |                   ^^^^ not found in `inner::right`
    |
 note: found an item that was configured out
-  --> $DIR/diagnostics-same-crate.rs:24:16
+  --> $DIR/diagnostics-same-crate.rs:26:16
    |
 LL |         pub fn meow() {}
    |                ^^^^
-   = note: the item is gated behind the `what-a-cool-feature` feature
+note: the item is gated behind the `what-a-cool-feature` feature
+  --> $DIR/diagnostics-same-crate.rs:25:15
+   |
+LL |         #[cfg(feature = "what-a-cool-feature")]
+   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0425]: cannot find function `uwu` in this scope
-  --> $DIR/diagnostics-same-crate.rs:43:5
+  --> $DIR/diagnostics-same-crate.rs:45:5
    |
 LL |     uwu();
    |     ^^^ not found in this scope
 
 error[E0425]: cannot find function `vanished` in this scope
-  --> $DIR/diagnostics-same-crate.rs:63:5
+  --> $DIR/diagnostics-same-crate.rs:64:5
    |
 LL |     vanished();
    |     ^^^^^^^^ not found in this scope

tests/ui/macros/builtin-std-paths-fail.stderr

@@ -104,6 +104,8 @@ LL | #[std::test]
    |
 note: found an item that was configured out
   --> $SRC_DIR/std/src/lib.rs:LL:COL
+note: the item is gated here
+  --> $SRC_DIR/std/src/lib.rs:LL:COL
 
 error: aborting due to 16 previous errors
 

tests/ui/macros/macro-outer-attributes.stderr

@@ -9,6 +9,17 @@ note: found an item that was configured out
    |
 LL |       pub fn bar() { });
    |              ^^^
+note: the item is gated here
+  --> $DIR/macro-outer-attributes.rs:5:45
+   |
+LL |                        $i:item) => (mod $nm { #[$a] $i }); }
+   |                                               ^^^^^
+LL |
+LL | / test!(a,
+LL | |       #[cfg(FALSE)],
+LL | |       pub fn bar() { });
+   | |_______________________- in this macro invocation
+   = note: this error originates in the macro `test` (in Nightly builds, run with -Z macro-backtrace for more info)
 help: consider importing this function
    |
 LL + use b::bar;