fix(destructuring): preserve loc of original declaration in output (#13173)

packages/babel-plugin-transform-destructuring/src/index.js

@@ -615,6 +615,7 @@ export default declare((api, options) => {
         if (!variableDeclarationHasPattern(node)) return;
 
         const nodeKind = node.kind;
+        const nodeLoc = node.loc;
         const nodes = [];
         let declar;
 
@@ -664,6 +665,10 @@ export default declare((api, options) => {
           } else {
             // Make sure the original node kind is used for each compound declaration
             node.kind = nodeKind;
+            // Propagate the original declaration node's location
+            if (!node.loc) {
+              node.loc = nodeLoc;
+            }
             nodesOut.push(node);
             tail = t.isVariableDeclaration(node) ? node : null;
           }

packages/babel-plugin-transform-destructuring/test/fixtures/sourcemap/declaration-loc/input.js

@@ -0,0 +1,3 @@
+const fn = (arg) => {
+  var [x, y] = arg;
+}

packages/babel-plugin-transform-destructuring/test/fixtures/sourcemap/declaration-loc/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-destructuring"]
+}

packages/babel-plugin-transform-destructuring/test/fixtures/sourcemap/declaration-loc/output.js

@@ -0,0 +1,5 @@
+const fn = arg => {
+  var _arg = babelHelpers.slicedToArray(arg, 2),
+      x = _arg[0],
+      y = _arg[1];
+};

packages/babel-plugin-transform-destructuring/test/fixtures/sourcemap/declaration-loc/source-mappings.json

@@ -0,0 +1,10 @@
+[{
+  "original": {
+    "line": 2,
+    "column": 2
+  },
+  "generated": {
+    "line": 2,
+    "column": 2
+  }
+}]