feat(linter): support --print-config to print config file for project

apps/oxlint/fixtures/print_config/ban_rules/eslintrc.json

@@ -0,0 +1,9 @@
+{
+  "rules": {
+    "no-debugger": "warn",
+    "eqeqeq": [
+      "warn",
+      "always"
+    ]
+  }
+}

apps/oxlint/fixtures/print_config/ban_rules/expect.json

@@ -0,0 +1,44 @@
+{
+  "plugins": [
+    "react",
+    "unicorn",
+    "typescript",
+    "oxc"
+  ],
+  "categories": {},
+  "rules": {
+    "eqeqeq": [
+      "deny",
+      [
+        "always"
+      ]
+    ]
+  },
+  "settings": {
+    "jsx-a11y": {
+      "polymorphicPropName": null,
+      "components": {}
+    },
+    "next": {
+      "rootDir": []
+    },
+    "react": {
+      "formComponents": [],
+      "linkComponents": []
+    },
+    "jsdoc": {
+      "ignorePrivate": false,
+      "ignoreInternal": false,
+      "ignoreReplacesDocs": true,
+      "overrideReplacesDocs": true,
+      "augmentsExtendsReplacesDocs": false,
+      "implementsReplacesDocs": false,
+      "exemptDestructuredRootsFromChecks": false,
+      "tagNamePreference": {}
+    }
+  },
+  "env": {
+    "builtin": true
+  },
+  "globals": {}
+}

apps/oxlint/fixtures/print_config/normal/expect.json

@@ -0,0 +1,37 @@
+{
+  "plugins": [
+    "react",
+    "unicorn",
+    "typescript",
+    "oxc"
+  ],
+  "categories": {},
+  "rules": {},
+  "settings": {
+    "jsx-a11y": {
+      "polymorphicPropName": null,
+      "components": {}
+    },
+    "next": {
+      "rootDir": []
+    },
+    "react": {
+      "formComponents": [],
+      "linkComponents": []
+    },
+    "jsdoc": {
+      "ignorePrivate": false,
+      "ignoreInternal": false,
+      "ignoreReplacesDocs": true,
+      "overrideReplacesDocs": true,
+      "augmentsExtendsReplacesDocs": false,
+      "implementsReplacesDocs": false,
+      "exemptDestructuredRootsFromChecks": false,
+      "tagNamePreference": {}
+    }
+  },
+  "env": {
+    "builtin": true
+  },
+  "globals": {}
+}

apps/oxlint/src/command/mod.rs

@@ -25,6 +25,11 @@ pub struct MiscOptions {
     /// Number of threads to use. Set to 1 for using only 1 CPU core
     #[bpaf(argument("INT"), hide_usage)]
     pub threads: Option<usize>,
+
+    /// This option outputs the configuration to be used.
+    /// When present, no linting is performed and only config-related options are valid.
+    #[bpaf(switch, hide_usage)]
+    pub print_config: bool,
 }
 
 #[allow(clippy::ptr_arg)]

apps/oxlint/src/lint.rs

@@ -116,10 +116,19 @@ impl Runner for LintRunner {
         };
 
         enable_plugins.apply_overrides(&mut oxlintrc.plugins);
+
+        let oxlintrc_for_print =
+            if misc_options.print_config { Some(oxlintrc.clone()) } else { None };
         let builder = LinterBuilder::from_oxlintrc(false, oxlintrc)
             .with_filters(filter)
             .with_fix(fix_options.fix_kind());
 
+        if let Some(basic_config_file) = oxlintrc_for_print {
+            return CliRunResult::PrintConfigResult {
+                config_file: builder.resolve_final_config_file(basic_config_file),
+            };
+        }
+
         let mut options =
             LintServiceOptions::new(cwd, paths).with_cross_module(builder.plugins().has_import());
         let linter = builder.build();
@@ -586,4 +595,40 @@ mod test {
         // Write the file back.
         fs::write(file, content).unwrap();
     }
+
+    #[test]
+    fn test_print_config_ban_all_rules() {
+        let args = &["-A", "all", "--print-config"];
+        let options = lint_command().run_inner(args).unwrap();
+        let ret = LintRunner::new(options).run();
+        let CliRunResult::PrintConfigResult { config_file: config } = ret else {
+            panic!("Expected PrintConfigResult, got {ret:?}")
+        };
+
+        let expect_json =
+            std::fs::read_to_string("fixtures/print_config/normal/expect.json").unwrap();
+        assert_eq!(config, expect_json.trim());
+    }
+
+    #[test]
+    fn test_print_config_ban_rules() {
+        let args = &[
+            "-c",
+            "fixtures/print_config/ban_rules/eslintrc.json",
+            "-A",
+            "all",
+            "-D",
+            "eqeqeq",
+            "--print-config",
+        ];
+        let options = lint_command().run_inner(args).unwrap();
+        let ret = LintRunner::new(options).run();
+        let CliRunResult::PrintConfigResult { config_file: config } = ret else {
+            panic!("Expected PrintConfigResult, got {ret:?}")
+        };
+
+        let expect_json =
+            std::fs::read_to_string("fixtures/print_config/ban_rules/expect.json").unwrap();
+        assert_eq!(config, expect_json.trim());
+    }
 }

apps/oxlint/src/result.rs

@@ -12,6 +12,7 @@ pub enum CliRunResult {
     LintResult(LintResult),
     FormatResult(FormatResult),
     TypeCheckResult { duration: Duration, number_of_diagnostics: usize },
+    PrintConfigResult { config_file: String },
 }
 
 #[derive(Debug, Default)]
@@ -107,6 +108,10 @@ impl Termination for CliRunResult {
 
                 ExitCode::from(0)
             }
+            Self::PrintConfigResult { config_file } => {
+                println!("{config_file}");
+                ExitCode::from(0)
+            }
         }
     }
 }

crates/oxc_linter/src/builder.rs

@@ -3,12 +3,15 @@ use std::{
     fmt,
 };
 
+use oxc_span::CompactStr;
 use rustc_hash::FxHashSet;
 
 use crate::{
-    options::LintPlugins, rules::RULES, AllowWarnDeny, FixKind, FrameworkFlags, LintConfig,
-    LintFilter, LintFilterKind, LintOptions, Linter, Oxlintrc, RuleCategory, RuleEnum,
-    RuleWithSeverity,
+    config::{ESLintRule, OxlintRules},
+    options::LintPlugins,
+    rules::RULES,
+    AllowWarnDeny, FixKind, FrameworkFlags, LintConfig, LintFilter, LintFilterKind, LintOptions,
+    Linter, Oxlintrc, RuleCategory, RuleEnum, RuleWithSeverity,
 };
 
 #[must_use = "You dropped your builder without building a Linter! Did you mean to call .build()?"]
@@ -244,6 +247,44 @@ impl LinterBuilder {
             .map(|rule| RuleWithSeverity { rule: rule.clone(), severity: AllowWarnDeny::Warn })
             .collect()
     }
+
+    /// # Panics
+    /// This function will panic if the `oxlintrc` is not valid JSON.
+    pub fn resolve_final_config_file(&self, oxlintrc: Oxlintrc) -> String {
+        let mut oxlintrc = oxlintrc;
+        let previous_rules = std::mem::take(&mut oxlintrc.rules);
+
+        let rule_name_to_rule = previous_rules
+            .into_iter()
+            .map(|r| (get_name(&r.plugin_name, &r.rule_name), r))
+            .collect::<rustc_hash::FxHashMap<_, _>>();
+
+        let new_rules = self
+            .rules
+            .iter()
+            .map(|r: &RuleWithSeverity| {
+                return ESLintRule {
+                    plugin_name: r.plugin_name().to_string(),
+                    rule_name: r.rule.name().to_string(),
+                    severity: r.severity,
+                    config: rule_name_to_rule
+                        .get(&get_name(r.plugin_name(), r.rule.name()))
+                        .and_then(|r| r.config.clone()),
+                };
+            })
+            .collect();
+
+        oxlintrc.rules = OxlintRules::new(new_rules);
+        serde_json::to_string_pretty(&oxlintrc).unwrap()
+    }
+}
+
+fn get_name(plugin_name: &str, rule_name: &str) -> CompactStr {
+    if plugin_name == "eslint" {
+        CompactStr::from(rule_name)
+    } else {
+        CompactStr::from(format!("{plugin_name}/{rule_name}"))
+    }
 }
 
 impl From<Oxlintrc> for LinterBuilder {

crates/oxc_linter/src/config/globals.rs

@@ -29,7 +29,7 @@ use serde::{de::Visitor, Deserialize, Serialize};
 /// You may also use `"readable"` or `false` to represent `"readonly"`, and
 /// `"writeable"` or `true` to represent `"writable"`.
 // <https://eslint.org/docs/v8.x/use/configure/language-options#using-configuration-files-1>
-#[derive(Debug, Default, Deserialize, Serialize, JsonSchema)]
+#[derive(Debug, Default, Deserialize, Serialize, JsonSchema, Clone)]
 pub struct OxlintGlobals(FxHashMap<String, GlobalValue>);
 impl OxlintGlobals {
     pub fn is_enabled<Q>(&self, name: &Q) -> bool

crates/oxc_linter/src/config/mod.rs

@@ -9,6 +9,8 @@ pub use self::{
     env::OxlintEnv,
     globals::OxlintGlobals,
     oxlintrc::Oxlintrc,
+    rules::ESLintRule,
+    rules::OxlintRules,
     settings::{jsdoc::JSDocPluginSettings, OxlintSettings},
 };
 

crates/oxc_linter/src/config/oxlintrc.rs

@@ -43,7 +43,7 @@ use crate::{options::LintPlugins, utils::read_to_string};
 ///   }
 ///  }
 /// ```
-#[derive(Debug, Default, Deserialize, Serialize, JsonSchema)]
+#[derive(Debug, Default, Clone, Deserialize, Serialize, JsonSchema)]
 #[serde(default)]
 #[non_exhaustive]
 pub struct Oxlintrc {

crates/oxc_linter/src/config/rules.rs

@@ -26,6 +26,12 @@ type RuleSet = FxHashSet<RuleWithSeverity>;
 #[cfg_attr(test, derive(PartialEq))]
 pub struct OxlintRules(Vec<ESLintRule>);
 
+impl OxlintRules {
+    pub fn new(rules: Vec<ESLintRule>) -> Self {
+        Self(rules)
+    }
+}
+
 #[derive(Debug, Clone)]
 #[cfg_attr(test, derive(PartialEq))]
 pub struct ESLintRule {

crates/oxc_linter/src/config/settings/jsdoc.rs

@@ -7,7 +7,7 @@ use serde::{Deserialize, Serialize};
 use crate::utils::default_true;
 
 // <https://github.com/gajus/eslint-plugin-jsdoc/blob/main/docs/settings.md>
-#[derive(Debug, Deserialize, Serialize, JsonSchema)]
+#[derive(Debug, Clone, Deserialize, Serialize, JsonSchema)]
 #[cfg_attr(test, derive(PartialEq))]
 pub struct JSDocPluginSettings {
     /// For all rules but NOT apply to `check-access` and `empty-tags` rule

crates/oxc_linter/src/config/settings/jsx_a11y.rs

@@ -4,7 +4,7 @@ use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
 
 // <https://github.com/jsx-eslint/eslint-plugin-jsx-a11y#configurations>
-#[derive(Debug, Deserialize, Default, Serialize, JsonSchema)]
+#[derive(Debug, Clone, Deserialize, Default, Serialize, JsonSchema)]
 #[cfg_attr(test, derive(PartialEq))]
 pub struct JSXA11yPluginSettings {
     #[serde(rename = "polymorphicPropName")]

crates/oxc_linter/src/config/settings/mod.rs

@@ -12,7 +12,7 @@ use self::{
 };
 
 /// Shared settings for plugins
-#[derive(Debug, Deserialize, Serialize, Default, JsonSchema)]
+#[derive(Debug, Clone, Deserialize, Serialize, Default, JsonSchema)]
 #[cfg_attr(test, derive(PartialEq))]
 pub struct OxlintSettings {
     #[serde(default)]

crates/oxc_linter/src/config/settings/next.rs

@@ -3,7 +3,7 @@ use std::borrow::Cow;
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize, Serializer};
 
-#[derive(Debug, Deserialize, Default, Serialize, JsonSchema)]
+#[derive(Debug, Clone, Deserialize, Default, Serialize, JsonSchema)]
 #[cfg_attr(test, derive(PartialEq))]
 pub struct NextPluginSettings {
     #[serde(default)]

crates/oxc_linter/src/config/settings/react.rs

@@ -5,7 +5,7 @@ use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
 
 // <https://github.com/jsx-eslint/eslint-plugin-react#configuration-legacy-eslintrc->
-#[derive(Debug, Deserialize, Default, Serialize, JsonSchema)]
+#[derive(Debug, Clone, Deserialize, Default, Serialize, JsonSchema)]
 #[cfg_attr(test, derive(PartialEq))]
 pub struct ReactPluginSettings {
     #[serde(default)]

tasks/website/src/linter/snapshots/cli.snap

@@ -117,6 +117,8 @@ Arguments:
   Do not display any diagnostics
 - **`    --threads`**=_`INT`_ — 
   Number of threads to use. Set to 1 for using only 1 CPU core
+- **`    --print-config`** — 
+  This option outputs the configuration to be used. When present, no linting is performed and only config-related options are valid.
 
 
 

tasks/website/src/linter/snapshots/cli_terminal.snap

@@ -72,6 +72,8 @@ Output
 Miscellaneous
         --silent              Do not display any diagnostics
         --threads=INT         Number of threads to use. Set to 1 for using only 1 CPU core
+        --print-config        This option outputs the configuration to be used. When present, no
+                              linting is performed and only config-related options are valid.
 
 Available positional items:
     PATH                      Single file, single path or list of paths