facebook · motiz88 · Apr 25, 2023
diff --git a/packages/metro-source-map/src/Generator.js b/packages/metro-source-map/src/Generator.js
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
+ * @flow strict-local
  * @format
  * @oncall react_native
  */
@@ -19,6 +19,10 @@ import type {
 
 const B64Builder = require('./B64Builder');
 
+type FileFlags = $ReadOnly<{
+  addToIgnoreList?: boolean,
+}>;
+
 /**
  * Generates a source map from raw mappings.
  *
@@ -45,6 +49,8 @@ class Generator {
   sources: Array<string>;
   sourcesContent: Array<?string>;
   x_facebook_sources: Array<?FBSourceMetadata>;
+  // https://developer.chrome.com/blog/devtools-better-angular-debugging/#the-x_google_ignorelist-source-map-extension
+  x_google_ignoreList: Array<number>;
 
   constructor() {
     this.builder = new B64Builder();
@@ -61,15 +67,26 @@ class Generator {
     this.sources = [];
     this.sourcesContent = [];
     this.x_facebook_sources = [];
+    this.x_google_ignoreList = [];
   }
 
   /**
    * Mark the beginning of a new source file.
    */
-  startFile(file: string, code: string, functionMap: ?FBSourceFunctionMap) {
-    this.source = this.sources.push(file) - 1;
+  startFile(
+    file: string,
+    code: string,
+    functionMap: ?FBSourceFunctionMap,
+    flags?: FileFlags,
+  ) {
+    const {addToIgnoreList = false} = flags ?? {};
+    const sourceIndex = this.sources.push(file) - 1;
+    this.source = sourceIndex;
     this.sourcesContent.push(code);
     this.x_facebook_sources.push(functionMap ? [functionMap] : null);
+    if (addToIgnoreList) {
+      this.x_google_ignoreList.push(sourceIndex);
+    }
   }
 
   /**
@@ -159,32 +176,41 @@ class Generator {
     file?: string,
     options?: {excludeSource?: boolean, ...},
   ): BasicSourceMap {
-    let content, sourcesMetadata;
+    const content: {
+      sourcesContent?: Array<?string>,
+    } =
+      options && options.excludeSource === true
+        ? {}
+        : {sourcesContent: this.sourcesContent.slice()};
 
-    if (options && options.excludeSource) {
-      content = {};
-    } else {
-      content = {sourcesContent: this.sourcesContent.slice()};
-    }
+    const sourcesMetadata: {
+      x_facebook_sources?: Array<FBSourceMetadata>,
+    } = this.hasSourcesMetadata()
+      ? {
+          x_facebook_sources: JSON.parse(
+            JSON.stringify(this.x_facebook_sources),
+          ),
+        }
+      : {};
 
-    if (this.hasSourcesMetadata()) {
-      sourcesMetadata = {
-        x_facebook_sources: JSON.parse(JSON.stringify(this.x_facebook_sources)),
-      };
-    } else {
-      sourcesMetadata = {};
-    }
+    const ignoreList: {
+      x_google_ignoreList?: Array<number>,
+    } = this.x_google_ignoreList.length
+      ? {
+          x_google_ignoreList: this.x_google_ignoreList,
+        }
+      : {};
 
-    return {
+    return ({
       version: 3,
       file,
       sources: this.sources.slice(),
-      // $FlowFixMe[exponential-spread]
       ...content,
       ...sourcesMetadata,
+      ...ignoreList,
       names: this.names.items(),
       mappings: this.builder.toString(),
-    };
+    }: BasicSourceMap);
   }
 
   /**
@@ -193,14 +219,14 @@ class Generator {
    * This is ~2.5x faster than calling `JSON.stringify(generator.toMap())`
    */
   toString(file?: string, options?: {excludeSource?: boolean, ...}): string {
-    let content, sourcesMetadata;
-
-    if (options && options.excludeSource) {
+    let content;
+    if (options && options.excludeSource === true) {
       content = '';
     } else {
       content = `"sourcesContent":${JSON.stringify(this.sourcesContent)},`;
     }
 
+    let sourcesMetadata;
     if (this.hasSourcesMetadata()) {
       sourcesMetadata = `"x_facebook_sources":${JSON.stringify(
         this.x_facebook_sources,
@@ -209,13 +235,23 @@ class Generator {
       sourcesMetadata = '';
     }
 
+    let ignoreList;
+    if (this.x_google_ignoreList.length) {
+      ignoreList = `"x_google_ignoreList":${JSON.stringify(
+        this.x_google_ignoreList,
+      )},`;
+    } else {
+      ignoreList = '';
+    }
+
     return (
       '{' +
       '"version":3,' +
-      (file ? `"file":${JSON.stringify(file)},` : '') +
+      (file != null ? `"file":${JSON.stringify(file)},` : '') +
       `"sources":${JSON.stringify(this.sources)},` +
       content +
       sourcesMetadata +
+      ignoreList +
       `"names":${JSON.stringify(this.names.items())},` +
       `"mappings":"${this.builder.toString()}"` +
       '}'

diff --git a/packages/metro-source-map/src/__tests__/Generator-test.js b/packages/metro-source-map/src/__tests__/Generator-test.js
@@ -100,7 +100,9 @@ describe('full map generation', () => {
     generator.addSimpleMapping(1, 2);
     generator.addNamedSourceMapping(3, 4, 5, 6, 'plums');
     generator.endFile();
-    generator.startFile('lemons', 'oranges');
+    generator.startFile('lemons', 'oranges', undefined, {
+      addToIgnoreList: true,
+    });
     generator.addNamedSourceMapping(7, 8, 9, 10, 'tangerines');
     generator.addNamedSourceMapping(11, 12, 13, 14, 'tangerines');
     generator.addSimpleMapping(15, 16);
@@ -113,6 +115,7 @@ describe('full map generation', () => {
       sources: ['apples', 'lemons'],
       sourcesContent: ['pears', 'oranges'],
       names: ['plums', 'tangerines'],
+      x_google_ignoreList: [1],
     });
   });
 
@@ -133,3 +136,38 @@ describe('full map generation', () => {
     expect(JSON.parse(generator.toString(file))).toEqual(generator.toMap(file));
   });
 });
+
+describe('x_google_ignoreList', () => {
+  it('add files to ignore list', () => {
+    const file1 = 'just/a/file';
+    const file2 = 'another/file';
+    const file3 = 'file3';
+    const source1 = 'var a = 1;';
+    const source2 = 'var a = 2;';
+
+    generator.startFile(file1, source1, undefined, {addToIgnoreList: true});
+    generator.startFile(file2, source2, undefined, {addToIgnoreList: false});
+    generator.startFile(file3, source2, undefined, {addToIgnoreList: true});
+
+    expect(generator.toMap()).toEqual(
+      objectContaining({
+        sources: [file1, file2, file3],
+        x_google_ignoreList: [0, 2],
+      }),
+    );
+  });
+
+  it('not emitted if no files are ignored', () => {
+    const file1 = 'just/a/file';
+    const file2 = 'another/file';
+    const file3 = 'file3';
+    const source1 = 'var a = 1;';
+    const source2 = 'var a = 2;';
+
+    generator.startFile(file1, source1);
+    generator.startFile(file2, source2, undefined, {addToIgnoreList: false});
+    generator.startFile(file3, source2, undefined, {addToIgnoreList: false});
+
+    expect(generator.toMap()).not.toHaveProperty('x_google_ignoreList');
+  });
+});
diff --git a/packages/metro-source-map/src/__tests__/composeSourceMaps-test.js b/packages/metro-source-map/src/__tests__/composeSourceMaps-test.js
@@ -20,6 +20,8 @@ const {add0, add1} = require('ob1');
 const path = require('path');
 const terser = require('terser');
 
+const {objectContaining} = expect;
+
 /* eslint-disable no-multi-str */
 
 const TestScript1 =
@@ -165,6 +167,91 @@ describe('composeSourceMaps', () => {
     ]);
   });
 
+  it('preserves and reindexes x_google_ignoreList', () => {
+    const map1 = {
+      version: 3,
+      sections: [
+        {
+          offset: {line: 0, column: 0},
+          map: {
+            version: 3,
+            sources: ['unused.js', 'src.js'],
+            x_google_ignoreList: [1],
+            names: ['global'],
+            mappings: ';CCCCA',
+          },
+        },
+      ],
+    };
+
+    const map2 = {
+      version: 3,
+      sources: ['src-transformed.js'],
+      names: ['gLoBAl'],
+      mappings: ';CACCA',
+    };
+
+    const mergedMap = composeSourceMaps([map1, map2]);
+
+    expect(mergedMap).toEqual(
+      objectContaining({
+        sources: ['src.js'],
+        x_google_ignoreList: [0],
+      }),
+    );
+  });
+
+  it('x_google_ignoreList: a source with inconsistent ignore status is considered to be ignored', () => {
+    const map1 = {
+      version: 3,
+      sections: [
+        {
+          offset: {line: 0, column: 0},
+          map: {
+            version: 3,
+            sources: ['unused.js', 'src.js'],
+            x_google_ignoreList: [1],
+            names: ['global'],
+            // First line of src-transformed.js maps to src.js (source #1 here)
+            mappings: 'ACAAA',
+          },
+        },
+        {
+          offset: {line: 1, column: 0},
+          map: {
+            version: 3,
+            sources: ['src.js', 'other.js'],
+            x_google_ignoreList: ([]: Array<number>),
+            names: ['global'],
+
+            mappings:
+              // Second line of src-transformed.js maps to src.js (source #0 here)
+              'AAAAA' +
+              // Third line of src-transformed.js maps to other.js (source #1 here)
+              ';ACAAA',
+          },
+        },
+      ],
+    };
+
+    const map2 = {
+      version: 3,
+      sources: ['src-transformed.js'],
+      names: ['gLoBAl'],
+      // Map each line to itself
+      mappings: 'AAAAA;AACAA;AACAA',
+    };
+
+    const mergedMap = composeSourceMaps([map1, map2]);
+
+    expect(mergedMap).toEqual(
+      objectContaining({
+        sources: ['src.js', 'other.js'],
+        x_google_ignoreList: [0],
+      }),
+    );
+  });
+
   it('preserves sourcesContent', () => {
     const map1 = {
       version: 3,

diff --git a/packages/metro-source-map/src/composeSourceMaps.js b/packages/metro-source-map/src/composeSourceMaps.js
@@ -27,6 +27,7 @@ function composeSourceMaps(
 ): MixedSourceMap {
   // NOTE: require() here to break dependency cycle
   const SourceMetadataMapConsumer = require('metro-symbolicate/src/SourceMetadataMapConsumer');
+  const GoogleIgnoreListConsumer = require('metro-symbolicate/src/GoogleIgnoreListConsumer');
   if (maps.length < 1) {
     throw new Error('composeSourceMaps: Expected at least one map');
   }
@@ -81,6 +82,11 @@ function composeSourceMaps(
   if (function_offsets) {
     composedMap.x_hermes_function_offsets = function_offsets;
   }
+  const ignoreListConsumer = new GoogleIgnoreListConsumer(firstMap);
+  const x_google_ignoreList = ignoreListConsumer.toArray(composedMap.sources);
+  if (x_google_ignoreList.length) {
+    composedMap.x_google_ignoreList = x_google_ignoreList;
+  }
   return composedMap;
 }
 

diff --git a/packages/metro-source-map/src/source-map.js b/packages/metro-source-map/src/source-map.js
@@ -59,6 +59,7 @@ export type BasicSourceMap = {
   +x_facebook_sources?: FBSourcesArray,
   +x_facebook_segments?: FBSegmentMap,
   +x_hermes_function_offsets?: HermesFunctionOffsets,
+  +x_google_ignoreList?: Array<number>,
 };
 
 export type IndexMapSection = {
@@ -82,6 +83,7 @@ export type IndexMap = {
   +x_facebook_sources?: void,
   +x_facebook_segments?: FBSegmentMap,
   +x_hermes_function_offsets?: HermesFunctionOffsets,
+  +x_google_ignoreList?: void,
 };
 
 export type MixedSourceMap = IndexMap | BasicSourceMap;