From 2dafe2d288d1e0d353bb938d12a5da888091cfdb Mon Sep 17 00:00:00 2001
From: Milos Djermanovic <milos.djermanovic@gmail.com>
Date: Wed, 17 Jul 2019 07:04:51 +0200
Subject: [PATCH] Fix: prefer-const produces invalid autofix (fixes #11699)
 (#11827)

---
 lib/rules/prefer-const.js       | 12 +++++++++---
 tests/lib/rules/prefer-const.js | 20 +++++++++++++++++++-
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/lib/rules/prefer-const.js b/lib/rules/prefer-const.js
index 68c07da4ed9..854da310e4b 100644
--- a/lib/rules/prefer-const.js
+++ b/lib/rules/prefer-const.js
@@ -420,8 +420,9 @@ module.exports = {
 
                 let shouldFix = varDeclParent &&
 
-                    // Don't do a fix unless the variable is initialized (or it's in a for-in or for-of loop)
-                    (varDeclParent.parent.type === "ForInStatement" || varDeclParent.parent.type === "ForOfStatement" || varDeclParent.declarations[0].init) &&
+                    // Don't do a fix unless all variables in the declarations are initialized (or it's in a for-in or for-of loop)
+                    (varDeclParent.parent.type === "ForInStatement" || varDeclParent.parent.type === "ForOfStatement" ||
+                        varDeclParent.declarations.every(declaration => declaration.init)) &&
 
                     /*
                      * If options.destructuring is "all", then this warning will not occur unless
@@ -450,7 +451,12 @@ module.exports = {
                         node,
                         messageId: "useConst",
                         data: node,
-                        fix: shouldFix ? fixer => fixer.replaceText(sourceCode.getFirstToken(varDeclParent), "const") : null
+                        fix: shouldFix
+                            ? fixer => fixer.replaceText(
+                                sourceCode.getFirstToken(varDeclParent, t => t.value === varDeclParent.kind),
+                                "const"
+                            )
+                            : null
                     });
                 });
             }
diff --git a/tests/lib/rules/prefer-const.js b/tests/lib/rules/prefer-const.js
index d8c018bdf3c..d923985337b 100644
--- a/tests/lib/rules/prefer-const.js
+++ b/tests/lib/rules/prefer-const.js
@@ -508,7 +508,25 @@ ruleTester.run("prefer-const", rule, {
                 { message: "'a' is never reassigned. Use 'const' instead.", type: "Identifier" },
                 { message: "'b' is never reassigned. Use 'const' instead.", type: "Identifier" }
             ]
-        }
+        },
 
+        // https://github.com/eslint/eslint/issues/11699
+        {
+            code: "let {a, b} = c, d;",
+            output: null,
+            errors: [
+                { messageId: "useConst", data: { name: "a" }, type: "Identifier" },
+                { messageId: "useConst", data: { name: "b" }, type: "Identifier" }
+            ]
+        },
+        {
+            code: "let {a, b, c} = {}, e, f;",
+            output: null,
+            errors: [
+                { messageId: "useConst", data: { name: "a" }, type: "Identifier" },
+                { messageId: "useConst", data: { name: "b" }, type: "Identifier" },
+                { messageId: "useConst", data: { name: "c" }, type: "Identifier" }
+            ]
+        }
     ]
 });