Fixed disappearing comments following a trailing comma on the last pr…

…operty of an object literal or the last argument of a call expression (babel#478) (babel#551)
wcjohnson · May 31, 2017 · 8a8cc1a · 8a8cc1a
1 parent 990675d
commit 8a8cc1a
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Showing 7 changed files with 772 additions and 1 deletion.
diff --git a/src/parser/comments.js b/src/parser/comments.js
@@ -43,7 +43,7 @@ pp.processComment = function (node) {
 
   const stack = this.state.commentStack;
 
-  let lastChild, trailingComments, i, j;
+  let firstChild, lastChild, trailingComments, i, j;
 
   if (this.state.trailingComments.length > 0) {
     // If the first comment in trailingComments comes after the
@@ -71,10 +71,41 @@ pp.processComment = function (node) {
   }
 
   // Eating the stack.
+  if (stack.length > 0 && last(stack).start >= node.start) {
+    firstChild = stack.pop();
+  }
+
   while (stack.length > 0 && last(stack).start >= node.start) {
     lastChild = stack.pop();
   }
 
+  if (!lastChild && firstChild) lastChild = firstChild;
+
+  // Attach comments that follow a trailing comma on the last
+  // property in an object literal or a trailing comma in function arguments
+  // as trailing comments
+  if (firstChild &&
+        (firstChild.type === "ObjectProperty" ||
+        (node.type === "CallExpression")) &&
+        this.state.leadingComments.length > 0) {
+    const lastComment = last(this.state.leadingComments);
+    if (lastComment.start >= node.start) {
+      if (this.state.commentPreviousNode) {
+        for (j = 0; j < this.state.leadingComments.length; j++) {
+          if (this.state.leadingComments[j].end < this.state.commentPreviousNode.end) {
+            this.state.leadingComments.splice(j, 1);
+            j--;
+          }
+        }
+
+        if (this.state.leadingComments.length > 0) {
+          firstChild.trailingComments = this.state.leadingComments;
+          this.state.leadingComments = [];
+        }
+      }
+    }
+  }
+
   if (lastChild) {
     if (lastChild.leadingComments) {
       if (lastChild !== node && last(lastChild.leadingComments).end <= node.start) {

diff --git a/test/fixtures/comments/basic/function-trailing-comma-shorthand/actual.js b/test/fixtures/comments/basic/function-trailing-comma-shorthand/actual.js
@@ -0,0 +1 @@
+fn(a, { b }, /* comment */);
diff --git a/test/fixtures/comments/basic/function-trailing-comma-shorthand/expected.json b/test/fixtures/comments/basic/function-trailing-comma-shorthand/expected.json
@@ -0,0 +1,208 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 28,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 1,
+      "column": 28
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 28,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 1,
+        "column": 28
+      }
+    },
+    "sourceType": "script",
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start": 0,
+        "end": 28,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 28
+          }
+        },
+        "expression": {
+          "type": "CallExpression",
+          "start": 0,
+          "end": 27,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 0
+            },
+            "end": {
+              "line": 1,
+              "column": 27
+            }
+          },
+          "callee": {
+            "type": "Identifier",
+            "start": 0,
+            "end": 2,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 0
+              },
+              "end": {
+                "line": 1,
+                "column": 2
+              },
+              "identifierName": "fn"
+            },
+            "name": "fn"
+          },
+          "arguments": [
+            {
+              "type": "Identifier",
+              "start": 3,
+              "end": 4,
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 3
+                },
+                "end": {
+                  "line": 1,
+                  "column": 4
+                },
+                "identifierName": "a"
+              },
+              "name": "a"
+            },
+            {
+              "type": "ObjectExpression",
+              "start": 6,
+              "end": 11,
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 6
+                },
+                "end": {
+                  "line": 1,
+                  "column": 11
+                }
+              },
+              "properties": [
+                {
+                  "type": "ObjectProperty",
+                  "start": 8,
+                  "end": 9,
+                  "loc": {
+                    "start": {
+                      "line": 1,
+                      "column": 8
+                    },
+                    "end": {
+                      "line": 1,
+                      "column": 9
+                    }
+                  },
+                  "method": false,
+                  "shorthand": true,
+                  "computed": false,
+                  "key": {
+                    "type": "Identifier",
+                    "start": 8,
+                    "end": 9,
+                    "loc": {
+                      "start": {
+                        "line": 1,
+                        "column": 8
+                      },
+                      "end": {
+                        "line": 1,
+                        "column": 9
+                      },
+                      "identifierName": "b"
+                    },
+                    "name": "b"
+                  },
+                  "value": {
+                    "type": "Identifier",
+                    "start": 8,
+                    "end": 9,
+                    "loc": {
+                      "start": {
+                        "line": 1,
+                        "column": 8
+                      },
+                      "end": {
+                        "line": 1,
+                        "column": 9
+                      },
+                      "identifierName": "b"
+                    },
+                    "name": "b"
+                  },
+                  "extra": {
+                    "shorthand": true
+                  }
+                }
+              ],
+              "trailingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " comment ",
+                  "start": 13,
+                  "end": 26,
+                  "loc": {
+                    "start": {
+                      "line": 1,
+                      "column": 13
+                    },
+                    "end": {
+                      "line": 1,
+                      "column": 26
+                    }
+                  }
+                }
+              ]
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " comment ",
+      "start": 13,
+      "end": 26,
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 13
+        },
+        "end": {
+          "line": 1,
+          "column": 26
+        }
+      }
+    }
+  ]
+}
diff --git a/test/fixtures/comments/basic/function-trailing-comma/actual.js b/test/fixtures/comments/basic/function-trailing-comma/actual.js
@@ -0,0 +1 @@
+fn(a, b, /* comment */);