Support msg({...}) descriptor form and add auto-fix

- Allow msg() function call form: _(msg({message: 'Hello'}))
- Add auto-fix for string literals: _('Bad') -> _(msg`Bad`)
- Add auto-fix for untagged templates: _(`Bad`) -> _(msg`Bad`)
- No auto-fix for variables/function calls (not safely fixable)

https://claude.ai/code/session_01JMXXPUgAHiSBGmfGwUojKy

eslint/__tests__/lingui-msg-rule.test.js

@@ -57,79 +57,128 @@ const position = 1
 const x = _(selectOrdinal(position, {one: '#st', two: '#nd', few: '#rd', other: '#th'}))
         `,
       },
-      // Different function named _ (not from useLingui context, but rule doesn't track that)
-      // This is fine - the rule just checks the pattern
+      // msg function call with object (descriptor form)
       {
         code: `
-const _ = (x) => x
-const x = _(someValue)
+const {_} = useLingui()
+const x = _(msg({message: 'Hello'}))
+        `,
+      },
+      // msg function call with object and context
+      {
+        code: `
+const {_} = useLingui()
+const x = _(msg({message: 'Hello', context: 'greeting'}))
         `,
       },
     ],
     invalid: [
-      // Plain string literal (single quotes)
+      // Plain string literal (single quotes) - with auto-fix
       {
         code: `
 const {_} = useLingui()
 const x = _('Bad')
+        `,
+        output: `
+const {_} = useLingui()
+const x = _(msg\`Bad\`)
         `,
         errors: [{messageId: 'missingMsg'}],
       },
-      // Plain string literal (double quotes)
+      // Plain string literal (double quotes) - with auto-fix
       {
         code: `
 const {_} = useLingui()
 const x = _("Bad")
+        `,
+        output: `
+const {_} = useLingui()
+const x = _(msg\`Bad\`)
         `,
         errors: [{messageId: 'missingMsg'}],
       },
-      // Template literal without msg tag
+      // Template literal without msg tag - with auto-fix
       {
         code: `
 const {_} = useLingui()
 const x = _(\`Bad\`)
+        `,
+        output: `
+const {_} = useLingui()
+const x = _(msg\`Bad\`)
         `,
         errors: [{messageId: 'missingMsg'}],
       },
-      // Variable/identifier
+      // Template literal with interpolation - with auto-fix
+      {
+        code: `
+const {_} = useLingui()
+const name = 'World'
+const x = _(\`Hello \${name}\`)
+        `,
+        output: `
+const {_} = useLingui()
+const name = 'World'
+const x = _(msg\`Hello \${name}\`)
+        `,
+        errors: [{messageId: 'missingMsg'}],
+      },
+      // String with backticks that need escaping
+      {
+        code: `
+const {_} = useLingui()
+const x = _('Use \\\`code\\\` here')
+        `,
+        output: `
+const {_} = useLingui()
+const x = _(msg\`Use \\\`code\\\` here\`)
+        `,
+        errors: [{messageId: 'missingMsg'}],
+      },
+      // Variable/identifier - no auto-fix possible
       {
         code: `
 const {_} = useLingui()
 const message = 'Hello'
 const x = _(message)
         `,
+        output: null,
         errors: [{messageId: 'missingMsg'}],
       },
-      // Arbitrary function call
+      // Arbitrary function call - no auto-fix possible
       {
         code: `
 const {_} = useLingui()
 const x = _(getMessage())
         `,
+        output: null,
         errors: [{messageId: 'missingMsg'}],
       },
-      // Empty call
+      // Empty call - no auto-fix possible
       {
         code: `
 const {_} = useLingui()
 const x = _()
         `,
+        output: null,
         errors: [{messageId: 'missingMsg'}],
       },
-      // Tagged template with wrong tag
+      // Tagged template with wrong tag - no auto-fix (would need to replace tag)
       {
         code: `
 const {_} = useLingui()
 const x = _(html\`Hello\`)
         `,
+        output: null,
         errors: [{messageId: 'missingMsg'}],
       },
-      // Number literal
+      // Number literal - no auto-fix possible
       {
         code: `
 const {_} = useLingui()
 const x = _(123)
         `,
+        output: null,
         errors: [{messageId: 'missingMsg'}],
       },
     ],

eslint/lingui-msg-rule.js

@@ -11,9 +11,10 @@ module.exports = {
         'Enforce that Lingui _() function is called with msg`` template literal or plural/select macros',
       recommended: true,
     },
+    fixable: 'code',
     messages: {
       missingMsg:
-        'Lingui _() must be called with msg`...` template literal or plural/select/selectOrdinal. Example: _(msg`Hello`)',
+        'Lingui _() must be called with msg`...` or msg({...}) or plural/select/selectOrdinal. Example: _(msg`Hello`)',
     },
     schema: [],
   },
@@ -21,11 +22,45 @@ module.exports = {
   create(context) {
     // Valid Lingui macro functions that can be passed to _()
     const VALID_MACRO_FUNCTIONS = new Set([
+      'msg',
       'plural',
       'select',
       'selectOrdinal',
     ])
 
+    /**
+     * Escape backticks and backslashes for template literal
+     */
+    function escapeForTemplateLiteral(str) {
+      return str.replace(/\\`/g, '`').replace(/`/g, '\\`')
+    }
+
+    /**
+     * Try to get a fixer for the given argument
+     * Returns null if we can't safely fix it
+     */
+    function getFixer(firstArg) {
+      const sourceCode = context.sourceCode ?? context.getSourceCode()
+
+      // Fix string literals: _('foo') -> _(msg`foo`)
+      if (firstArg.type === 'Literal' && typeof firstArg.value === 'string') {
+        const escaped = escapeForTemplateLiteral(firstArg.value)
+        return function (fixer) {
+          return fixer.replaceText(firstArg, 'msg`' + escaped + '`')
+        }
+      }
+
+      // Fix untagged template literals: _(`foo`) -> _(msg`foo`)
+      if (firstArg.type === 'TemplateLiteral') {
+        const text = sourceCode.getText(firstArg)
+        return function (fixer) {
+          return fixer.replaceText(firstArg, 'msg' + text)
+        }
+      }
+
+      return null
+    }
+
     return {
       CallExpression(node) {
         // Check if this is a call to _()
@@ -53,7 +88,7 @@ module.exports = {
           return
         }
 
-        // Valid: _(plural(...)), _(select(...)), _(selectOrdinal(...))
+        // Valid: _(msg(...)), _(plural(...)), _(select(...)), _(selectOrdinal(...))
         if (
           firstArg.type === 'CallExpression' &&
           firstArg.callee.type === 'Identifier' &&
@@ -63,9 +98,11 @@ module.exports = {
         }
 
         // Everything else is invalid
+        const fix = getFixer(firstArg)
         context.report({
           node,
           messageId: 'missingMsg',
+          fix,
         })
       },
     }