fix #3144: fill in null entries in source maps

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+* Fill in `null` entries in input source maps ([#3144](https://github.com/evanw/esbuild/issues/3144))
+
+ If esbuild bundles input files with source maps and those source maps contain a `sourcesContent` array with `null` entries, esbuild previously copied those `null` entries over to the output source map. With this release, esbuild will now attempt to fill in those `null` entries by looking for a file on the file system with the corresponding name from the `sources` array. This matches esbuild's existing behavior that automatically generates the `sourcesContent` array from the file system if the entire `sourcesContent` array is missing.
+
 ## 0.18.0
 
 **This release deliberately contains backwards-incompatible changes.** To avoid automatically picking up releases like this, you should either be pinning the exact version of `esbuild` in your `package.json` file (recommended) or be using a version range syntax that only accepts patch upgrades such as `^0.17.0` or `~0.17.0`. See npm's documentation about [semver](https://docs.npmjs.com/cli/v6/using-npm/semver/) for more information.

internal/bundler/bundler.go

@@ -480,23 +480,33 @@ func parseFile(args parseArgs) {
  }
  }
 
- // If "sourcesContent" isn't present, try filling it in using the file system
- if sourceMap != nil && sourceMap.SourcesContent == nil && !args.options.ExcludeSourcesContent {
- for _, source := range sourceMap.Sources {
- var absPath string
- if args.fs.IsAbs(source) {
- absPath = source
- } else if path.Namespace == "file" {
- absPath = args.fs.Join(args.fs.Dir(path.Text), source)
- } else {
- sourceMap.SourcesContent = append(sourceMap.SourcesContent, sourcemap.SourceContent{})
- continue
- }
- var sourceContent sourcemap.SourceContent
- if contents, err, _ := args.caches.FSCache.ReadFile(args.fs, absPath); err == nil {
- sourceContent.Value = helpers.StringToUTF16(contents)
+ // If "sourcesContent" entries aren't present, try filling them in
+ // using the file system. This includes both generating the entire
+ // "sourcesContent" array if it's absent as well as filling in
+ // individual null entries in the array if the array is present.
+ if sourceMap != nil && !args.options.ExcludeSourcesContent {
+ // Make sure "sourcesContent" is big enough
+ if len(sourceMap.SourcesContent) < len(sourceMap.Sources) {
+ slice := make([]sourcemap.SourceContent, len(sourceMap.Sources))
+ copy(slice, sourceMap.SourcesContent)
+ sourceMap.SourcesContent = slice
+ }
+
+ // Attempt to fill in null entries using the file system
+ for i, source := range sourceMap.Sources {
+ if sourceMap.SourcesContent[i].Value == nil {
+ var absPath string
+ if args.fs.IsAbs(source) {
+ absPath = source
+ } else if path.Namespace == "file" {
+ absPath = args.fs.Join(args.fs.Dir(path.Text), source)
+ } else {
+ continue
+ }
+ if contents, err, _ := args.caches.FSCache.ReadFile(args.fs, absPath); err == nil {
+ sourceMap.SourcesContent[i].Value = helpers.StringToUTF16(contents)
+ }
  }
- sourceMap.SourcesContent = append(sourceMap.SourcesContent, sourceContent)
  }
  }
 

scripts/verify-source-map.js

@@ -402,6 +402,34 @@ const toSearchMissingSourcesContent = {
  bar: 'src/foo.ts',
 }
 
+// The "null" should be filled in by the contents of "bar.ts"
+const testCaseNullSourcesContent = {
+ 'entry.js': `import './foo.js'\n`,
+ 'foo.ts': `import './bar.ts'\nconsole.log("foo")`,
+ 'bar.ts': `console.log("bar")\n`,
+ 'foo.js': `(() => {
+ // bar.ts
+ console.log("bar");
+
+ // foo.ts
+ console.log("foo");
+})();
+//# sourceMappingURL=foo.js.map
+`,
+ 'foo.js.map': `{
+ "version": 3,
+ "sources": ["bar.ts", "foo.ts"],
+ "sourcesContent": [null, "import './bar.ts'\\nconsole.log(\\"foo\\")"],
+ "mappings": ";;AAAA,UAAQ,IAAI,KAAK;;;ACCjB,UAAQ,IAAI,KAAK;",
+ "names": []
+}
+`,
+}
+
+const toSearchNullSourcesContent = {
+ bar: 'bar.ts',
+}
+
 async function check(kind, testCase, toSearch, { ext, flags, entryPoints, crlf, followUpFlags = [] }) {
  let failed = 0
 
@@ -856,13 +884,21 @@ async function main() {
  crlf,
  }),
 
- // Checks for loading missing sources content in nested source maps
+ // Checks for loading missing "sourcesContent" in nested source maps
  check('missing-sources-content' + suffix, testCaseMissingSourcesContent, toSearchMissingSourcesContent, {
  ext: 'js',
  flags: flags.concat('--outfile=out.js', '--bundle'),
  entryPoints: ['foo.js'],
  crlf,
  }),
+
+ // Checks for null entries in "sourcesContent" in nested source maps
+ check('null-sources-content' + suffix, testCaseNullSourcesContent, toSearchNullSourcesContent, {
+ ext: 'js',
+ flags: flags.concat('--outfile=out.js', '--bundle'),
+ entryPoints: ['foo.js'],
+ crlf,
+ }),
  )
  }
  }