Rollup merge of #116428 - Alexendoo:note-duplicate-diagnostics, r=compiler-errors,estebank

Add a note to duplicate diagnostics

Helps explain why there may be a difference between manual testing and the test suite output and highlights them as something to potentially look into

For existing duplicate diagnostics I just blessed them other than a few files that had other `NOTE` annotations in

Author: matthiaskrgr

compiler/rustc_errors/src/lib.rs

@@ -1376,16 +1376,16 @@ impl HandlerInner {
                 self.emitted_diagnostic_codes.insert(code.clone());
             }
 
-            let already_emitted = |this: &mut Self| {
+            let already_emitted = {
                 let mut hasher = StableHasher::new();
                 diagnostic.hash(&mut hasher);
                 let diagnostic_hash = hasher.finish();
-                !this.emitted_diagnostics.insert(diagnostic_hash)
+                !self.emitted_diagnostics.insert(diagnostic_hash)
             };
 
             // Only emit the diagnostic if we've been asked to deduplicate or
             // haven't already emitted an equivalent diagnostic.
-            if !(self.flags.deduplicate_diagnostics && already_emitted(self)) {
+            if !(self.flags.deduplicate_diagnostics && already_emitted) {
                 debug!(?diagnostic);
                 debug!(?self.emitted_diagnostics);
                 let already_emitted_sub = |sub: &mut SubDiagnostic| {
@@ -1401,6 +1401,11 @@ impl HandlerInner {
                 };
 
                 diagnostic.children.extract_if(already_emitted_sub).for_each(|_| {});
+                if already_emitted {
+                    diagnostic.note(
+                        "duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`",
+                    );
+                }
 
                 self.emitter.emit_diagnostic(diagnostic);
                 if diagnostic.is_error() {

tests/rustdoc-ui/custom_code_classes_in_docs-warning3.stderr

@@ -28,6 +28,8 @@ LL | |
 LL | | /// main;
 LL | | /// ```
    | |_______^
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: aborting due to 2 previous errors
 

tests/rustdoc-ui/intra-doc/broken-link-in-unused-doc-string.stderr

@@ -22,6 +22,7 @@ LL | /// [1]
    |      ^ no item named `1` in scope
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: 3 warnings emitted
 

tests/rustdoc-ui/issues/issue-105742.stderr

@@ -169,6 +169,7 @@ note: associated type defined here, with 1 lifetime parameter: `'a`
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing lifetime argument
    |
 LL |     <Self as SVec>::Item<'a>,
@@ -185,6 +186,7 @@ note: associated type defined here, with 1 generic parameter: `T`
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing generic argument
    |
 LL |     <Self as SVec>::Item<T>,
@@ -201,6 +203,7 @@ note: associated type defined here, with 1 lifetime parameter: `'a`
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing lifetime argument
    |
 LL |     Output = <Index<<Self as SVec>::Item<'a>,
@@ -217,6 +220,7 @@ note: associated type defined here, with 1 generic parameter: `T`
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing generic argument
    |
 LL |     Output = <Index<<Self as SVec>::Item<T>,
@@ -233,6 +237,7 @@ note: associated type defined here, with 1 lifetime parameter: `'a`
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing lifetime argument
    |
 LL |     Output = <Self as SVec>::Item<'a>> as SVec>::Item,
@@ -249,6 +254,7 @@ note: associated type defined here, with 1 generic parameter: `T`
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing generic argument
    |
 LL |     Output = <Self as SVec>::Item<T>> as SVec>::Item,
@@ -265,6 +271,7 @@ note: associated type defined here, with 1 lifetime parameter: `'a`
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing lifetime argument
    |
 LL |     Output = <Self as SVec>::Item> as SVec>::Item<'a>,
@@ -281,6 +288,7 @@ note: associated type defined here, with 1 generic parameter: `T`
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing generic argument
    |
 LL |     Output = <Self as SVec>::Item> as SVec>::Item<T>,
@@ -327,6 +335,7 @@ note: associated type defined here, with 1 lifetime parameter: `'a`
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing lifetime argument
    |
 LL |     <Self as SVec>::Item<'a>,
@@ -343,6 +352,7 @@ note: associated type defined here, with 1 generic parameter: `T`
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing generic argument
    |
 LL |     <Self as SVec>::Item<T>,
@@ -359,6 +369,7 @@ note: associated type defined here, with 1 lifetime parameter: `'a`
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing lifetime argument
    |
 LL |     Output = <Index<<Self as SVec>::Item<'a>,
@@ -375,6 +386,7 @@ note: associated type defined here, with 1 generic parameter: `T`
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing generic argument
    |
 LL |     Output = <Index<<Self as SVec>::Item<T>,
@@ -391,6 +403,7 @@ note: associated type defined here, with 1 lifetime parameter: `'a`
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing lifetime argument
    |
 LL |     Output = <Self as SVec>::Item<'a>> as SVec>::Item,
@@ -407,6 +420,7 @@ note: associated type defined here, with 1 generic parameter: `T`
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing generic argument
    |
 LL |     Output = <Self as SVec>::Item<T>> as SVec>::Item,
@@ -423,6 +437,7 @@ note: associated type defined here, with 1 lifetime parameter: `'a`
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing lifetime argument
    |
 LL |     Output = <Self as SVec>::Item> as SVec>::Item<'a>,
@@ -439,6 +454,7 @@ note: associated type defined here, with 1 generic parameter: `T`
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: add missing generic argument
    |
 LL |     Output = <Self as SVec>::Item> as SVec>::Item<T>,

tests/rustdoc-ui/lints/feature-gate-rustdoc_missing_doc_code_examples.rs

@@ -1,12 +1,7 @@
+// compile-flags: -Zdeduplicate-diagnostics=yes
 #![deny(unknown_lints)]
 //~^ NOTE defined here
 #![allow(rustdoc::missing_doc_code_examples)]
 //~^ ERROR unknown lint
-//~| ERROR unknown lint
-//~| ERROR unknown lint
 //~| NOTE lint is unstable
-//~| NOTE lint is unstable
-//~| NOTE lint is unstable
-//~| NOTE see issue
-//~| NOTE see issue
 //~| NOTE see issue

tests/rustdoc-ui/lints/feature-gate-rustdoc_missing_doc_code_examples.stderr

@@ -1,5 +1,5 @@
 error: unknown lint: `rustdoc::missing_doc_code_examples`
-  --> $DIR/feature-gate-rustdoc_missing_doc_code_examples.rs:3:1
+  --> $DIR/feature-gate-rustdoc_missing_doc_code_examples.rs:4:1
    |
 LL | #![allow(rustdoc::missing_doc_code_examples)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -8,30 +8,10 @@ LL | #![allow(rustdoc::missing_doc_code_examples)]
    = note: see issue #101730 <https://github.com/rust-lang/rust/issues/101730> for more information
    = help: add `#![feature(rustdoc_missing_doc_code_examples)]` to the crate attributes to enable
 note: the lint level is defined here
-  --> $DIR/feature-gate-rustdoc_missing_doc_code_examples.rs:1:9
+  --> $DIR/feature-gate-rustdoc_missing_doc_code_examples.rs:2:9
    |
 LL | #![deny(unknown_lints)]
    |         ^^^^^^^^^^^^^
 
-error: unknown lint: `rustdoc::missing_doc_code_examples`
-  --> $DIR/feature-gate-rustdoc_missing_doc_code_examples.rs:3:1
-   |
-LL | #![allow(rustdoc::missing_doc_code_examples)]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: the `rustdoc::missing_doc_code_examples` lint is unstable
-   = note: see issue #101730 <https://github.com/rust-lang/rust/issues/101730> for more information
-   = help: add `#![feature(rustdoc_missing_doc_code_examples)]` to the crate attributes to enable
-
-error: unknown lint: `rustdoc::missing_doc_code_examples`
-  --> $DIR/feature-gate-rustdoc_missing_doc_code_examples.rs:3:1
-   |
-LL | #![allow(rustdoc::missing_doc_code_examples)]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: the `rustdoc::missing_doc_code_examples` lint is unstable
-   = note: see issue #101730 <https://github.com/rust-lang/rust/issues/101730> for more information
-   = help: add `#![feature(rustdoc_missing_doc_code_examples)]` to the crate attributes to enable
-
-error: aborting due to 3 previous errors
+error: aborting due to previous error
 

tests/rustdoc-ui/unescaped_backticks.stderr

@@ -302,6 +302,7 @@ LL | |     /// level changes.
    = help: if you meant to use a literal backtick, escape it
             change: or `None` if it isn't.
            to this: or `None\` if it isn't.
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: unescaped backtick
   --> $DIR/unescaped_backticks.rs:323:5
@@ -321,6 +322,7 @@ LL | |     /// level changes.
    = help: if you meant to use a literal backtick, escape it
             change: `on_event` should be called.
            to this: `on_event\` should be called.
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: unescaped backtick
   --> $DIR/unescaped_backticks.rs:323:5
@@ -340,6 +342,7 @@ LL | |     /// level changes.
    = help: if you meant to use a literal backtick, escape it
             change: [`rebuild_interest_cache`][rebuild] is called after the value of the max
            to this: [`rebuild_interest_cache\`][rebuild] is called after the value of the max
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: unescaped backtick
   --> $DIR/unescaped_backticks.rs:349:56

tests/ui-fulldeps/plugin/lint-plugin-forbid-attrs.stderr

@@ -27,6 +27,8 @@ LL | #![forbid(test_lint)]
 ...
 LL | #[allow(test_lint)]
    |         ^^^^^^^^^ overruled by previous forbid
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: use of deprecated attribute `plugin`: compiler plugins are deprecated. See https://github.com/rust-lang/rust/pull/64675
   --> $DIR/lint-plugin-forbid-attrs.rs:5:1

tests/ui-fulldeps/plugin/lint-plugin-forbid-cmdline.stderr

@@ -21,6 +21,7 @@ LL | #[allow(test_lint)]
    |         ^^^^^^^^^ overruled by previous forbid
    |
    = note: `forbid` lint level was set on command line
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: use of deprecated attribute `plugin`: compiler plugins are deprecated. See https://github.com/rust-lang/rust/pull/64675
   --> $DIR/lint-plugin-forbid-cmdline.rs:6:1

tests/ui-fulldeps/plugin/lint-tool-cmdline-allow.stderr

@@ -8,6 +8,7 @@ warning: lint name `test_lint` is deprecated and may not have an effect in the f
    |
    = help: change it to clippy::test_lint
    = note: requested on the command line with `-A test_lint`
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: item is named 'lintme'
   --> $DIR/lint-tool-cmdline-allow.rs:9:1
@@ -29,6 +30,7 @@ warning: lint name `test_lint` is deprecated and may not have an effect in the f
    |
    = help: change it to clippy::test_lint
    = note: requested on the command line with `-A test_lint`
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: 5 warnings emitted