Fix jashkenas#4558: Much more robust caching of sources and source ma…

…ps, more careful lookup of source maps especially for CoffeeScript code compiled within a Coffee script (. . . within a Coffee script, etc.)

src/coffeescript.coffee

@@ -14,7 +14,7 @@ packageJson = require '../../package.json'
 # The current CoffeeScript version number.
 exports.VERSION = packageJson.version
 
-exports.FILE_EXTENSIONS = ['.coffee', '.litcoffee', '.coffee.md']
+exports.FILE_EXTENSIONS = FILE_EXTENSIONS = ['.coffee', '.litcoffee', '.coffee.md']
 
 # Expose helpers for testing.
 exports.helpers = helpers
@@ -266,15 +266,35 @@ formatSourcePosition = (frame, getSourceMapping) ->
  else
  fileLocation
 
-getSourceMap = (filename) ->
- if sourceMaps[filename]?
- sourceMaps[filename][sourceMaps[filename].length - 1]
+getSourceMap = (filename, line, column) ->
+ # Skip files that we didn’t compile, like Node system files that appear in
+ # the stack trace, as they never have source maps.
+ return null unless filename is '<anonymous>' or filename.slice(filename.lastIndexOf('.')) in FILE_EXTENSIONS
+
+ if filename isnt '<anonymous>' and sourceMaps[filename]?
+ return sourceMaps[filename][sourceMaps[filename].length - 1]
+ # CoffeeScript compiled in a browser or via `CoffeeScript.compile` or `.run`
+ # may get compiled with `options.filename` that’s missing, which becomes
+ # `<anonymous>`; but the runtime might request the stack trace with the
+ # filename of the script file. See if we have a source map cached under
+ # `<anonymous>` that matches the error.
  else if sourceMaps['<anonymous>']?
- # CoffeeScript compiled in a browser may get compiled with `options.filename`
- # of `<anonymous>`, but the browser may request the stack trace with the
- # filename of the script file.
- sourceMaps['<anonymous>'][sourceMaps['<anonymous>'].length - 1]
- else if sources[filename]?
+ # Work backwards from the most recent anonymous source maps, until we find
+ # one that works. This isn’t foolproof; there is a chance that multiple
+ # source maps will have line/column pairs that match. But we have no other
+ # way to match them. `frame.getFunction().toString()` doesn’t always work,
+ # and it’s not foolproof either.
+ for map in sourceMaps['<anonymous>'] by -1
+ sourceLocation = map.sourceLocation [line - 1, column - 1]
+ return map if sourceLocation?[0]? and sourceLocation[1]?
+
+ # If all else fails, recompile this source to get a source map. We need the
+ # previous section (for `<anonymous>`) despite this option, because after it
+ # gets compiled we will still need to look it up from
+ # `sourceMaps['<anonymous>']` in order to find and return it. That’s why we
+ # start searching from the end in the previous block, because most of the
+ # time the source map we want is the last one.
+ if sources[filename]?
  answer = compile sources[filename][sources[filename].length - 1],
  filename: filename
  sourceMap: yes
@@ -289,7 +309,7 @@ getSourceMap = (filename) ->
 # positions.
 Error.prepareStackTrace = (err, stack) ->
  getSourceMapping = (filename, line, column) ->
- sourceMap = getSourceMap filename
+ sourceMap = getSourceMap filename, line, column
  answer = sourceMap.sourceLocation [line - 1, column - 1] if sourceMap?
  if answer? then [answer[0] + 1, answer[1] + 1] else null
 

test/error_messages.coffee

@@ -75,7 +75,7 @@ if require?
  finally
  fs.unlinkSync tempFile
 
- test "#3890 Error.prepareStackTrace doesn't throw an error if a compiled file is deleted", ->
+ test "#3890: Error.prepareStackTrace doesn't throw an error if a compiled file is deleted", ->
  # Adapted from https://github.com/atom/coffee-cash/blob/master/spec/coffee-cash-spec.coffee
  filePath = path.join os.tmpdir(), 'PrepareStackTraceTestFile.coffee'
  fs.writeFileSync filePath, "module.exports = -> throw new Error('hello world')"
@@ -90,7 +90,7 @@ if require?
  doesNotThrow(-> error.stack)
  notEqual error.stack.toString().indexOf(filePath), -1
 
- test "#4418 stack traces for compiled files reference the correct line number", ->
+ test "#4418: stack traces for compiled files reference the correct line number", ->
  filePath = path.join os.tmpdir(), 'StackTraceLineNumberTestFile.coffee'
  fileContents = """
  testCompiledFileStackTraceLineNumber = ->
@@ -111,22 +111,39 @@ if require?
  eq /StackTraceLineNumberTestFile.coffee:(\d)/.exec(error.stack.toString())[1], '3'
 
 
-test "#4418 stack traces for compiled strings reference the correct line number", ->
+test "#4418: stack traces for compiled strings reference the correct line number", ->
  try
- CoffeeScript.run """
+ CoffeeScript.run '''
  testCompiledStringStackTraceLineNumber = ->
  # `a` on the next line is undefined and should throw a ReferenceError
  console.log a if true
 
  do testCompiledStringStackTraceLineNumber
- """
+ '''
  catch error
 
  # Make sure the line number reported is line 3 (the original Coffee source)
  # and not line 6 (the generated JavaScript).
  eq /testCompiledStringStackTraceLineNumber.*:(\d):/.exec(error.stack.toString())[1], '3'
 
 
+test "#4558: compiling a string inside a script doesn’t screw up stack trace line number", ->
+ try
+ CoffeeScript.run '''
+ testCompilingInsideAScriptDoesntScrewUpStackTraceLineNumber = ->
+ if require?
+ CoffeeScript = require './lib/coffeescript'
+ CoffeeScript.compile ''
+ throw new Error 'Some Error'
+
+ do testCompilingInsideAScriptDoesntScrewUpStackTraceLineNumber
+ '''
+ catch error
+
+ # Make sure the line number reported is line 5 (the original Coffee source)
+ # and not line 10 (the generated JavaScript).
+ eq /testCompilingInsideAScriptDoesntScrewUpStackTraceLineNumber.*:(\d):/.exec(error.stack.toString())[1], '5'
+
 test "#1096: unexpected generated tokens", ->
  # Implicit ends
  assertErrorFormat 'a:, b', '''