Fix #4491: import- and export-specific lexing should stop (#4492)

* Fix #4491: import- and export-specific lexing should stop

* split up tests

* fixes from code review

src/lexer.coffee

@@ -45,6 +45,7 @@ exports.Lexer = class Lexer
     @seenFor    = no             # Used to recognize FORIN, FOROF and FORFROM tokens.
     @seenImport = no             # Used to recognize IMPORT FROM? AS? tokens.
     @seenExport = no             # Used to recognize EXPORT FROM? AS? tokens.
+    @importSpecifierList = no    # Used to identify when in an IMPORT {...} FROM? ...
     @exportSpecifierList = no    # Used to identify when in an EXPORT {...} FROM? ...
 
     @chunkLine =
@@ -365,6 +366,8 @@ exports.Lexer = class Lexer
     indent = match[0]
 
     @seenFor = no
+    @seenImport = no unless @importSpecifierList
+    @seenExport = no unless @exportSpecifierList
 
     size = indent.length - 1 - indent.lastIndexOf '\n'
     noNewlines = @unfinished()
@@ -473,7 +476,11 @@ exports.Lexer = class Lexer
         @error message, origin[2] if message
       return value.length if skipToken
 
-    if value is '{' and prev?[0] is 'EXPORT'
+    if value is '{' and @seenImport
+      @importSpecifierList = yes
+    else if @importSpecifierList and value is '}'
+      @importSpecifierList = no
+    else if value is '{' and prev?[0] is 'EXPORT'
       @exportSpecifierList = yes
     else if @exportSpecifierList and value is '}'
       @exportSpecifierList = no
@@ -763,12 +770,12 @@ exports.Lexer = class Lexer
 
   # Validates escapes in strings and regexes.
   validateEscapes: (str, options = {}) ->
-    invalid_escape_regex =
+    invalidEscapeRegex =
       if options.isRegex
         REGEX_INVALID_ESCAPE
       else
         STRING_INVALID_ESCAPE
-    match = invalid_escape_regex.exec str
+    match = invalidEscapeRegex.exec str
     return unless match
     [[], before, octal, hex, unicode] = match
     message =

test/modules.coffee

@@ -773,3 +773,110 @@ test "#4451: `default` in an export statement is only treated as a keyword when
       "default": 1
     };
   """
+  eq toJS(input), output
+
+test "#4491: import- and export-specific lexing should stop after import/export statement", ->
+  input = """
+    import {
+      foo,
+      bar as baz
+    } from 'lib'
+
+    foo as
+    3 * as 4
+    from 'foo'
+    """
+  output = """
+    import {
+      foo,
+      bar as baz
+    } from 'lib';
+
+    foo(as);
+
+    3 * as(4);
+
+    from('foo');
+    """
+  eq toJS(input), output
+
+  input = """
+    import { foo, bar as baz } from 'lib'
+
+    foo as
+    3 * as 4
+    from 'foo'
+    """
+  output = """
+    import {
+      foo,
+      bar as baz
+    } from 'lib';
+
+    foo(as);
+
+    3 * as(4);
+
+    from('foo');
+    """
+  eq toJS(input), output
+
+  input = """
+    import * as lib from 'lib'
+
+    foo as
+    3 * as 4
+    from 'foo'
+    """
+  output = """
+    import * as lib from 'lib';
+
+    foo(as);
+
+    3 * as(4);
+
+    from('foo');
+    """
+  eq toJS(input), output
+
+  input = """
+    export {
+      foo,
+      bar
+    }
+
+    foo as
+    3 * as 4
+    from 'foo'
+    """
+  output = """
+    export {
+      foo,
+      bar
+    };
+
+    foo(as);
+
+    3 * as(4);
+
+    from('foo');
+    """
+  eq toJS(input), output
+
+  input = """
+    export * from 'lib'
+
+    foo as
+    3 * as 4
+    from 'foo'
+    """
+  output = """
+    export * from 'lib';
+
+    foo(as);
+
+    3 * as(4);
+
+    from('foo');
+    """
+  eq toJS(input), output