refactor(linter): severity and recommendation of lint rules (#5133)

Co-authored-by: arendjr <[email protected]>
Co-authored-by: Conaclos <[email protected]>

.changeset/spotty-buckets-hang.md

@@ -0,0 +1,33 @@
+---
+"@biomejs/biome": major
+---
+
+Reworked some recommended rules recommended to be less pedantic and blocking. This is a **breaking change** if your project relied on those rules to block the CI in case of violations; if that's the case, you should raise their severity level to **error**.
+
+Some rules aren't recommended anymore, and some others return a different severity.
+
+The following rules return a **warning** diagnostic:
+- `noDelete`
+- `noForEach`
+- `noSuspiciousSemicolonInJsx`
+- `noThisInStatic`
+- `noUnusedLabels`
+
+The following rules return an **information** diagnostic:
+- `noUselessCatch`
+- `noUselessConstructor`
+- `noUselessEmptyExport`
+- `noUselessFragments`
+- `noUselessLabel`
+- `noUselessLoneBlockStatements`
+- `noUselessSwitchCase`
+- `noUselessTernary`
+- `noUselessThisAlias`
+- `noUselessTypeConstraint`
+- `noFlatMapIdentity`
+
+The following rules aren't recommended anymore:
+- `noDelete`
+- `noForEach`
+
+The rule `noRenderReturnValue` is only recommended when the `react` domain is enabled.

crates/biome_analyze/src/rule.rs

@@ -414,7 +414,7 @@ impl RuleSource {
 
     pub fn to_rule_url(&self) -> String {
         match self {
-            Self::Clippy(rule_name) => format!("https://rust-lang.github.io/rust-clippy/master/#/{rule_name}"),
+            Self::Clippy(rule_name) => format!("https://rust-lang.github.io/rust-clippy/master/#{rule_name}"),
             Self::Eslint(rule_name) => format!("https://eslint.org/docs/latest/rules/{rule_name}"),
             Self::EslintGraphql(rule_name) => format!("https://the-guild.dev/graphql/eslint/rules/{rule_name}"),
             Self::EslintGraphqlSchemaLinter(rule_name) => format!("https://github.com/cjoudrey/graphql-schema-linter?tab=readme-ov-file#{rule_name}"),

crates/biome_cli/tests/snapshots/main_cases_handle_vue_files/check_stdin_write_unsafe_successfully.snap

@@ -1,6 +1,7 @@
 ---
 source: crates/biome_cli/tests/snap_test.rs
-expression: content
+expression: redactor(content)
+snapshot_kind: text
 ---
 # Input messages
 
@@ -21,7 +22,7 @@ delete a.c;
 import * as vueUse from "vue-use";
 import { Button } from "./components/Button.vue";
 
-a.c = undefined;
+delete a.c;
 </script>
 <template></template>
 ```

crates/biome_cli/tests/snapshots/main_cases_handle_vue_files/lint_stdin_write_unsafe_successfully.snap

@@ -1,6 +1,6 @@
 ---
 source: crates/biome_cli/tests/snap_test.rs
-expression: content
+expression: redactor(content)
 snapshot_kind: text
 ---
 # Input messages
@@ -20,7 +20,7 @@ var foo: string = "";
 ```block
 <script setup lang="ts">
 a === b;
-a.c = undefined;
+delete a.c;
 
 var foo: string = "";
 </script>

crates/biome_cli/tests/snapshots/main_cases_handle_vue_files/lint_vue_js_files.snap

@@ -1,6 +1,6 @@
 ---
 source: crates/biome_cli/tests/snap_test.rs
-expression: content
+expression: redactor(content)
 snapshot_kind: text
 ---
 ## `file.vue`
@@ -55,30 +55,7 @@ file.vue:2:3 lint/suspicious/noDoubleEquals  FIXABLE  ━━━━━━━━
 
 ```
 
-```block
-file.vue:3:1 lint/performance/noDelete  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
-
-  × Avoid the delete operator which can impact performance.
-  
-    1 │ <script setup lang="js">
-    2 │ a == b;
-  > 3 │ delete a.c;
-      │ ^^^^^^^^^^
-    4 │ 
-    5 │ var foo = "";
-  
-  i Unsafe fix: Use an undefined assignment instead.
-  
-    1 1 │   a == b;
-    2   │ - delete·a.c;
-      2 │ + a.c·=·undefined;
-    3 3 │   
-    4 4 │   var foo = "";
-  
-
-```
-
 ```block
 Checked 1 file in <TIME>. No fixes applied.
-Found 2 errors.
+Found 1 error.
 ```

crates/biome_cli/tests/snapshots/main_cases_handle_vue_files/lint_vue_ts_files.snap

@@ -1,6 +1,6 @@
 ---
 source: crates/biome_cli/tests/snap_test.rs
-expression: content
+expression: redactor(content)
 snapshot_kind: text
 ---
 ## `file.vue`
@@ -55,30 +55,7 @@ file.vue:2:3 lint/suspicious/noDoubleEquals  FIXABLE  ━━━━━━━━
 
 ```
 
-```block
-file.vue:3:1 lint/performance/noDelete  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
-
-  × Avoid the delete operator which can impact performance.
-  
-    1 │ <script setup lang="ts">
-    2 │ a == b;
-  > 3 │ delete a.c;
-      │ ^^^^^^^^^^
-    4 │ 
-    5 │ var foo: string = "";
-  
-  i Unsafe fix: Use an undefined assignment instead.
-  
-    1 1 │   a == b;
-    2   │ - delete·a.c;
-      2 │ + a.c·=·undefined;
-    3 3 │   
-    4 4 │   var foo: string = "";
-  
-
-```
-
 ```block
 Checked 1 file in <TIME>. No fixes applied.
-Found 2 errors.
+Found 1 error.
 ```

crates/biome_cli/tests/snapshots/main_commands_lint/lint_only_multiple_rules.snap

@@ -1,6 +1,7 @@
 ---
 source: crates/biome_cli/tests/snap_test.rs
-expression: content
+expression: redactor(content)
+snapshot_kind: text
 ---
 ## `check.js`
 
@@ -39,7 +40,7 @@ check.js:1:1 lint/suspicious/noDebugger  FIXABLE  ━━━━━━━━━━
 ```block
 check.js:1:11 lint/performance/noDelete  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
-  × Avoid the delete operator which can impact performance.
+  ! Avoid the delete operator which can impact performance.
   
   > 1 │ debugger; delete obj.prop; a === -0;
       │           ^^^^^^^^^^^^^^^
@@ -54,5 +55,6 @@ check.js:1:11 lint/performance/noDelete  FIXABLE  ━━━━━━━━━━
 
 ```block
 Checked 1 file in <TIME>. No fixes applied.
-Found 2 errors.
+Found 1 error.
+Found 1 warning.
 ```

crates/biome_cli/tests/snapshots/main_commands_lint/lint_only_rule_and_group.snap

@@ -1,6 +1,7 @@
 ---
 source: crates/biome_cli/tests/snap_test.rs
-expression: content
+expression: redactor(content)
+snapshot_kind: text
 ---
 ## `check.js`
 
@@ -39,7 +40,7 @@ check.js:1:1 lint/suspicious/noDebugger  FIXABLE  ━━━━━━━━━━
 ```block
 check.js:1:11 lint/performance/noDelete  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
-  × Avoid the delete operator which can impact performance.
+  ! Avoid the delete operator which can impact performance.
   
   > 1 │ debugger; delete obj.prop; a === -0;
       │           ^^^^^^^^^^^^^^^
@@ -54,5 +55,6 @@ check.js:1:11 lint/performance/noDelete  FIXABLE  ━━━━━━━━━━
 
 ```block
 Checked 1 file in <TIME>. No fixes applied.
-Found 2 errors.
+Found 1 error.
+Found 1 warning.
 ```

crates/biome_cli/tests/snapshots/main_commands_lint/lint_skip_group_with_enabled_rule.snap

@@ -1,6 +1,7 @@
 ---
 source: crates/biome_cli/tests/snap_test.rs
-expression: content
+expression: redactor(content)
+snapshot_kind: text
 ---
 ## `biome.json`
 
@@ -20,38 +21,10 @@ expression: content
 
 ```js
 debugger; delete obj.prop;
-```
-
-# Termination Message
-
-```block
-lint ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
-
-  × Some errors were emitted while running checks.
-  
-
-
 ```
 
 # Emitted Messages
 
-```block
-check.js:1:11 lint/performance/noDelete  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
-
-  × Avoid the delete operator which can impact performance.
-  
-  > 1 │ debugger; delete obj.prop;
-      │           ^^^^^^^^^^^^^^^
-  
-  i Unsafe fix: Use an undefined assignment instead.
-  
-  - debugger;·delete·obj.prop;
-  + debugger;·obj.prop·=·undefined;
-  
-
-```
-
 ```block
 Checked 1 file in <TIME>. No fixes applied.
-Found 1 error.
 ```

crates/biome_cli/tests/snapshots/main_commands_lint/lint_skip_rule.snap

@@ -1,6 +1,7 @@
 ---
 source: crates/biome_cli/tests/snap_test.rs
-expression: content
+expression: redactor(content)
+snapshot_kind: text
 ---
 ## `check.js`
 
@@ -21,22 +22,6 @@ lint ━━━━━━━━━━━━━━━━━━━━━━━━━
 
 # Emitted Messages
 
-```block
-check.js:1:11 lint/performance/noDelete  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
-
-  × Avoid the delete operator which can impact performance.
-  
-  > 1 │ debugger; delete obj.prop; a === -0;
-      │           ^^^^^^^^^^^^^^^
-  
-  i Unsafe fix: Use an undefined assignment instead.
-  
-  - debugger;·delete·obj.prop;·a·===·-0;
-  + debugger;·obj.prop·=·undefined;·a·===·-0;
-  
-
-```
-
 ```block
 check.js:1:28 lint/suspicious/noCompareNegZero  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
@@ -54,5 +39,5 @@ check.js:1:28 lint/suspicious/noCompareNegZero  FIXABLE  ━━━━━━━
 
 ```block
 Checked 1 file in <TIME>. No fixes applied.
-Found 2 errors.
+Found 1 error.
 ```

crates/biome_cli/tests/snapshots/main_commands_rage/with_linter_configuration.snap

@@ -69,7 +69,6 @@ Linter:
     complexity/noBannedTypes
     complexity/noEmptyTypeParameters
     complexity/noExtraBooleanCast
-    complexity/noForEach
     complexity/noMultipleSpacesInRegularExpressionLiterals
     complexity/noStaticOnlyClass
     complexity/noThisInStatic

crates/biome_css_analyze/tests/plugin/useLowercaseColors.grit.snap

@@ -1,6 +1,7 @@
 ---
 source: crates/biome_css_analyze/tests/spec_tests.rs
 expression: useLowercaseColors.grit
+snapshot_kind: text
 ---
 # Input
 ```css
@@ -16,7 +17,7 @@ div {
 ```
 useLowercaseColors.grit:3:12 plugin ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
-  ! Prefer lowercase colors
+  i Prefer lowercase colors
   
     1 │ div {
     2 │     color: red;

crates/biome_css_analyze/tests/spec_tests.rs

@@ -4,7 +4,6 @@ use biome_analyze::{
 use biome_css_parser::{parse_css, CssParserOptions};
 use biome_css_syntax::{CssFileSource, CssLanguage};
 use biome_diagnostics::advice::CodeSuggestionAdvice;
-use biome_diagnostics::{DiagnosticExt, Severity};
 use biome_fs::OsFileSystem;
 use biome_plugin_loader::AnalyzerGritPlugin;
 use biome_rowan::AstNode;
@@ -146,8 +145,7 @@ pub(crate) fn analyze_and_snap(
                 }
             }
 
-            let error = diag.with_severity(Severity::Warning);
-            diagnostics.push(diagnostic_to_string(file_name, input_code, error));
+            diagnostics.push(diagnostic_to_string(file_name, input_code, diag.into()));
             return ControlFlow::Continue(());
         }