Add help to allow lint for the implied by suggestion

compiler/rustc_middle/src/lint.rs

@@ -225,6 +225,9 @@ pub fn explain_lint_level_source(
                 err.note_once(format!(
                     "`{flag} {hyphen_case_lint_name}` implied by `{flag} {hyphen_case_flag_val}`"
                 ));
+                err.help_once(format!(
+                    "to override `{flag} {hyphen_case_flag_val}` add `#[allow({name})]`"
+                ));
             }
         }
         LintLevelSource::Node { name: lint_attr_name, span, reason, .. } => {

tests/ui-fulldeps/plugin/lint-group-plugin-deny-cmdline.stderr

@@ -13,6 +13,7 @@ LL | fn lintme() { }
    | ^^^^^^^^^^^^^^^
    |
    = note: `-D test-lint` implied by `-D lint-me`
+   = help: to override `-D lint-me` add `#[allow(test_lint)]`
 
 error: item is named 'pleaselintme'
   --> $DIR/lint-group-plugin-deny-cmdline.rs:12:1
@@ -21,6 +22,7 @@ LL | fn pleaselintme() { }
    | ^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D please-lint` implied by `-D lint-me`
+   = help: to override `-D lint-me` add `#[allow(please_lint)]`
 
 error: aborting due to 2 previous errors; 1 warning emitted
 

tests/ui-fulldeps/session-diagnostic/diagnostic-derive-doc-comment-field.stderr

@@ -23,7 +23,7 @@ LL |     arg: NotIntoDiagnosticArg,
    |
    = help: normalized in stderr
 note: required by a bound in `Diagnostic::set_arg`
-  --> $COMPILER_DIR/rustc_errors/src/diagnostic.rs:960:5
+  --> $COMPILER_DIR/rustc_errors/src/diagnostic.rs:968:5
 
 error: aborting due to 2 previous errors
 

tests/ui/derive-uninhabited-enum-38885.stderr

@@ -9,6 +9,7 @@ LL |     Void(Void),
    |
    = note: `Foo` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
    = note: `-W dead-code` implied by `-W unused`
+   = help: to override `-W unused` add `#[allow(dead_code)]`
 
 warning: 1 warning emitted
 

tests/ui/lint-group-forbid-always-trumps-cli.stderr

@@ -5,6 +5,7 @@ LL |     let x = 1;
    |         ^ help: if this is intentional, prefix it with an underscore: `_x`
    |
    = note: `-F unused-variables` implied by `-F unused`
+   = help: to override `-F unused` add `#[allow(unused_variables)]`
 
 error: aborting due to previous error
 

tests/ui/lint/command-line-lint-group-deny.stderr

@@ -5,6 +5,7 @@ LL |     let _InappropriateCamelCasing = true;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^ help: convert the identifier to snake case: `_inappropriate_camel_casing`
    |
    = note: `-D non-snake-case` implied by `-D bad-style`
+   = help: to override `-D bad-style` add `#[allow(non_snake_case)]`
 
 error: aborting due to previous error
 

tests/ui/lint/command-line-lint-group-forbid.stderr

@@ -5,6 +5,7 @@ LL |     let _InappropriateCamelCasing = true;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^ help: convert the identifier to snake case: `_inappropriate_camel_casing`
    |
    = note: `-F non-snake-case` implied by `-F bad-style`
+   = help: to override `-F bad-style` add `#[allow(non_snake_case)]`
 
 error: aborting due to previous error
 

tests/ui/lint/command-line-lint-group-warn.stderr

@@ -5,6 +5,7 @@ LL |     let _InappropriateCamelCasing = true;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^ help: convert the identifier to snake case: `_inappropriate_camel_casing`
    |
    = note: `-W non-snake-case` implied by `-W bad-style`
+   = help: to override `-W bad-style` add `#[allow(non_snake_case)]`
 
 warning: 1 warning emitted
 

tests/ui/lint/force-warn/cap-lints-warn-allowed-warn-by-default-lint.stderr

@@ -7,6 +7,7 @@ LL |         0...100 => true,
    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
    = note: `--force-warn ellipsis-inclusive-range-patterns` implied by `--force-warn rust-2021-compatibility`
+   = help: to override `--force-warn rust-2021-compatibility` add `#[allow(ellipsis_inclusive_range_patterns)]`
 
 warning: 1 warning emitted
 

tests/ui/lint/force-warn/lint-group-allow-warnings.stderr

@@ -5,6 +5,7 @@ LL | pub fn FUNCTION() {}
    |        ^^^^^^^^ help: convert the identifier to snake case: `function`
    |
    = note: `--force-warn non-snake-case` implied by `--force-warn nonstandard-style`
+   = help: to override `--force-warn nonstandard-style` add `#[allow(non_snake_case)]`
 
 warning: 1 warning emitted
 

tests/ui/lint/force-warn/lint-group-allowed-cli-warn-by-default-lint.stderr

@@ -7,6 +7,7 @@ LL | pub fn function(_x: Box<SomeTrait>) {}
    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
    = note: `--force-warn bare-trait-objects` implied by `--force-warn rust-2018-idioms`
+   = help: to override `--force-warn rust-2018-idioms` add `#[allow(bare_trait_objects)]`
 help: use `dyn`
    |
 LL | pub fn function(_x: Box<dyn SomeTrait>) {}

tests/ui/lint/force-warn/lint-group-allowed-lint-group.stderr

@@ -7,6 +7,7 @@ LL | pub fn function(_x: Box<SomeTrait>) {}
    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
    = note: `--force-warn bare-trait-objects` implied by `--force-warn rust-2018-idioms`
+   = help: to override `--force-warn rust-2018-idioms` add `#[allow(bare_trait_objects)]`
 help: use `dyn`
    |
 LL | pub fn function(_x: Box<dyn SomeTrait>) {}

tests/ui/lint/force-warn/lint-group-allowed-warn-by-default-lint.stderr

@@ -7,6 +7,7 @@ LL | pub fn function(_x: Box<SomeTrait>) {}
    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
    = note: `--force-warn bare-trait-objects` implied by `--force-warn rust-2018-idioms`
+   = help: to override `--force-warn rust-2018-idioms` add `#[allow(bare_trait_objects)]`
 help: use `dyn`
    |
 LL | pub fn function(_x: Box<dyn SomeTrait>) {}

tests/ui/lint/future-incompat-test.stderr

@@ -6,4 +6,5 @@ LL |     let x = 1;
    |         ^ help: if this is intentional, prefix it with an underscore: `_x`
    |
    = note: `-A unused-variables` implied by `-A unused`
+   = help: to override `-A unused` add `#[allow(unused_variables)]`
 

tests/ui/lint/lint-pre-expansion-extern-module.stderr

@@ -7,6 +7,7 @@ LL | pub fn try() {}
    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2018!
    = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
    = note: `-W keyword-idents` implied by `-W rust-2018-compatibility`
+   = help: to override `-W rust-2018-compatibility` add `#[allow(keyword_idents)]`
 
 warning: 1 warning emitted
 

tests/ui/macros/must-use-in-macro-55516.stderr

@@ -6,6 +6,7 @@ LL |     write!(&mut example, "{}", 42);
    |
    = note: this `Result` may be an `Err` variant, which should be handled
    = note: `-W unused-must-use` implied by `-W unused`
+   = help: to override `-W unused` add `#[allow(unused_must_use)]`
    = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 warning: 1 warning emitted