From bbec2114ce55c9194f719a6a0f210ef92f25c250 Mon Sep 17 00:00:00 2001
From: Andrew Bradley <abradley@brightcove.com>
Date: Tue, 24 Nov 2015 16:07:37 -0500
Subject: [PATCH 1/2] Fixes T2864

- Drops input mappings that cannot be mapped through Babel's sourcemap
- For example, Babel's sourcemap does not have mappings for leading comments, so any mapping from an input sourcemap for those leading comments must be dropped from the merged sourcemap
---
 .../src/transformation/file/index.js          | 29 ++++++++++---------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/packages/babel-core/src/transformation/file/index.js b/packages/babel-core/src/transformation/file/index.js
index 5b47df51ea..58282100e2 100644
--- a/packages/babel-core/src/transformation/file/index.js
+++ b/packages/babel-core/src/transformation/file/index.js
@@ -360,20 +360,23 @@ export default class File extends Store {
       });
 
       inputMapConsumer.eachMapping(function (mapping) {
-        mergedGenerator.addMapping({
-          source: mapping.source,
-
-          original: {
-            line: mapping.originalLine,
-            column: mapping.originalColumn
-          },
-
-          generated: outputMapConsumer.generatedPositionFor({
-            line: mapping.generatedLine,
-            column: mapping.generatedColumn,
-            source: outputMapConsumer.file
-          })
+        const generatedPosition = outputMapConsumer.generatedPositionFor({
+          line: mapping.generatedLine,
+          column: mapping.generatedColumn,
+          source: outputMapConsumer.file
         });
+        if(generatedPosition.column != null) {
+          mergedGenerator.addMapping({
+            source: mapping.source,
+
+            original: {
+              line: mapping.originalLine,
+              column: mapping.originalColumn
+            },
+
+            generated: generatedPosition
+          });
+        }
       });
 
       let mergedMap = mergedGenerator.toJSON();

From 9c27f1e86a9c90312d7ae91249d8163b10b9067a Mon Sep 17 00:00:00 2001
From: Andrew Bradley <abradley@brightcove.com>
Date: Tue, 24 Nov 2015 16:10:10 -0500
Subject: [PATCH 2/2] Fixes the wrong source path being passed to
 SourceMapConsumer#generatedPositionFor

`generatedPositionFor` accepts a position in one of the sourcemap's *input* source files. Therefore the `source` path
should be one of the sourcemap's input `sources`, not the output `file`.
---
 packages/babel-core/src/transformation/file/index.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/packages/babel-core/src/transformation/file/index.js b/packages/babel-core/src/transformation/file/index.js
index 58282100e2..51dd9a43d4 100644
--- a/packages/babel-core/src/transformation/file/index.js
+++ b/packages/babel-core/src/transformation/file/index.js
@@ -359,11 +359,15 @@ export default class File extends Store {
         sourceRoot: inputMapConsumer.sourceRoot
       });
 
+      // This assumes the output map always has a single source, since Babel always compiles a single source file to a
+      // single output file.
+      const source = outputMapConsumer.sources[0];
+
       inputMapConsumer.eachMapping(function (mapping) {
         const generatedPosition = outputMapConsumer.generatedPositionFor({
           line: mapping.generatedLine,
           column: mapping.generatedColumn,
-          source: outputMapConsumer.file
+          source: source
         });
         if(generatedPosition.column != null) {
           mergedGenerator.addMapping({