diff --git a/mypy/fastparse.py b/mypy/fastparse.py
index 91f55ca99acf8..fa2d0bae4c63e 100644
--- a/mypy/fastparse.py
+++ b/mypy/fastparse.py
@@ -57,8 +57,10 @@ def parse(source: Union[str, bytes], fnam: str = None, errors: Errors = None,
 
     The pyversion (major, minor) argument determines the Python syntax variant.
     """
+    raise_on_error = False
     if errors is None:
         errors = Errors()
+        raise_on_error = True
     errors.set_file('<input>' if fnam is None else fnam)
     is_stub_file = bool(fnam) and fnam.endswith('.pyi')
     try:
@@ -72,14 +74,14 @@ def parse(source: Union[str, bytes], fnam: str = None, errors: Errors = None,
                             ).visit(ast)
         tree.path = fnam
         tree.is_stub = is_stub_file
-        return tree
     except SyntaxError as e:
-        if errors:
-            errors.report(e.lineno, e.offset, e.msg)
-        else:
-            raise
+        errors.report(e.lineno, e.offset, e.msg)
+        tree = MypyFile([], [], False, set())
+
+    if raise_on_error and errors.is_errors():
+        errors.raise_error()
 
-    return MypyFile([], [], False, set())
+    return tree
 
 
 def parse_type_comment(type_comment: str, line: int, errors: Errors) -> Optional[Type]:
diff --git a/mypy/fastparse2.py b/mypy/fastparse2.py
index b619d5c3fe2aa..772e9ae941071 100644
--- a/mypy/fastparse2.py
+++ b/mypy/fastparse2.py
@@ -74,8 +74,10 @@ def parse(source: Union[str, bytes], fnam: str = None, errors: Errors = None,
 
     The pyversion (major, minor) argument determines the Python syntax variant.
     """
+    raise_on_error = False
     if errors is None:
         errors = Errors()
+        raise_on_error = True
     errors.set_file('<input>' if fnam is None else fnam)
     is_stub_file = bool(fnam) and fnam.endswith('.pyi')
     try:
@@ -89,14 +91,14 @@ def parse(source: Union[str, bytes], fnam: str = None, errors: Errors = None,
         assert isinstance(tree, MypyFile)
         tree.path = fnam
         tree.is_stub = is_stub_file
-        return tree
     except SyntaxError as e:
-        if errors:
-            errors.report(e.lineno, e.offset, e.msg)
-        else:
-            raise
+        errors.report(e.lineno, e.offset, e.msg)
+        tree = MypyFile([], [], False, set())
+
+    if raise_on_error and errors.is_errors():
+        errors.raise_error()
 
-    return MypyFile([], [], False, set())
+    return tree
 
 
 def with_line(f: Callable[['ASTConverter', T], U]) -> Callable[['ASTConverter', T], U]:
diff --git a/mypy/main.py b/mypy/main.py
index ea203f0f1a446..a38d3bd3c1383 100644
--- a/mypy/main.py
+++ b/mypy/main.py
@@ -225,8 +225,8 @@ def add_invertible_flag(flag: str,
     add_invertible_flag('--show-error-context', default=True,
                         dest='hide_error_context',
                         help='Precede errors with "note:" messages explaining context')
-    add_invertible_flag('--fast-parser', default=False,
-                        help="enable fast parser (recommended)")
+    add_invertible_flag('--no-fast-parser', default=True, dest='fast_parser',
+                        help="disable the fast parser (not recommended)")
     parser.add_argument('-i', '--incremental', action='store_true',
                         help="enable experimental module cache")
     parser.add_argument('--cache-dir', action='store', metavar='DIR',
diff --git a/mypy/options.py b/mypy/options.py
index 0d53c3dbc9cdf..77f9713e3f52b 100644
--- a/mypy/options.py
+++ b/mypy/options.py
@@ -114,7 +114,7 @@ def __init__(self) -> None:
         self.use_builtins_fixtures = False
 
         # -- experimental options --
-        self.fast_parser = False
+        self.fast_parser = True
         self.incremental = False
         self.cache_dir = defaults.CACHE_DIR
         self.debug_cache = False
diff --git a/test-data/unit/parse-errors.test b/test-data/unit/parse-errors.test
index f2251a9e6e2a6..22a3c5c50b006 100644
--- a/test-data/unit/parse-errors.test
+++ b/test-data/unit/parse-errors.test
@@ -12,245 +12,217 @@
 def f()
   pass
 [out]
-file:1: error: Parse error before end of line
-file:2: error: Inconsistent indentation
+file:1: error: invalid syntax
 
 [case testMissingIndent]
 if x:
 1
 [out]
-file:2: error: Expected an indented block
+file:2: error: invalid syntax
 
 [case testUnexpectedIndent]
 1
  2
 [out]
-file:2: error: Inconsistent indentation
+file:2: error: unexpected indent
 
 [case testInconsistentIndent]
 if x:
   1
    1
 [out]
-file:3: error: Inconsistent indentation
+file:3: error: unexpected indent
 
-[case testInconsistentIndent]
+[case testInconsistentIndent2]
 if x:
    1
   1
 [out]
-file:3: error: Inconsistent indentation
+file:3: error: unindent does not match any outer indentation level
 
 [case testInvalidBinaryOp]
 1>
 a*
 a+1*
 [out]
-file:1: error: Parse error before end of line
-file:2: error: Parse error before end of line
-file:3: error: Parse error before end of line
+file:1: error: invalid syntax
 
 [case testDoubleStar]
 **a
 [out]
-file:1: error: Parse error before **
+file:1: error: invalid syntax
 
 [case testInvalidSuperClass]
 class A(C[):
   pass
 [out]
-file:1: error: Parse error before )
-file:2: error: Parse error before end of file
+file:1: error: invalid syntax
 
 [case testMissingSuperClass]
 class A(:
   pass
 [out]
-file:1: error: Parse error before :
-file:2: error: Parse error before end of file
+file:1: error: invalid syntax
 
 [case testUnexpectedEof]
 if 1:
 [out]
-file:1: error: Expected an indented block
+file:1: error: unexpected EOF while parsing
 
 [case testInvalidKeywordArguments1]
 f(x=y, z)
 [out]
-file:1: error: Parse error before "z"
+file:1: error: positional argument follows keyword argument
 
 [case testInvalidKeywordArguments2]
-f(**x, y=z)
-[out]
-file:1: error: Parse error before "y"
-
-[case testInvalidKeywordArguments3]
 f(**x, y)
 [out]
-file:1: error: Parse error before "y"
-
-[case testInvalidVarArgs]
-f(*x, y)
-[out]
-file:1: error: Parse error before "y"
+file:1: error: positional argument follows keyword argument unpacking
 
 [case testInvalidBareAsteriskAndVarArgs2]
 def f(*x: A, *) -> None: pass
 [out]
-file:1: error: Parse error before )
-file:1: error: Parse error before end of line
+file:1: error: invalid syntax
 
 [case testInvalidBareAsteriskAndVarArgs3]
 def f(*, *x: A) -> None: pass
 [out]
-file:1: error: Parse error before *
-file:1: error: Parse error before end of line
+file:1: error: invalid syntax
 
 [case testInvalidBareAsteriskAndVarArgs4]
 def f(*, **x: A) -> None: pass
 [out]
-file:1: error: Parse error before **
-file:1: error: Parse error before end of line
+file:1: error: named arguments must follow bare *
 
 [case testInvalidBareAsterisk1]
 def f(*) -> None: pass
 [out]
-file:1: error: Parse error before )
-file:1: error: Parse error before end of line
+file:1: error: named arguments must follow bare *
 
 [case testInvalidBareAsterisk2]
 def f(x, *) -> None: pass
 [out]
-file:1: error: Parse error before )
-file:1: error: Parse error before end of line
+file:1: error: named arguments must follow bare *
 
 [case testInvalidFuncDefArgs1]
 def f(x = y, x): pass
 [out]
-file:1: error: Invalid argument list
+file:1: error: non-default argument follows default argument
 
 [case testInvalidFuncDefArgs3]
 def f(**x, y):
    pass
 [out]
-file:1: error: Invalid argument list
+file:1: error: invalid syntax
 
 [case testInvalidFuncDefArgs4]
 def f(**x, y=x):
     pass
 [out]
-file:1: error: Invalid argument list
+file:1: error: invalid syntax
 
 [case testInvalidStringLiteralType]
 def f(x:
      'A['
      ) -> None: pass
 [out]
-file:2: error: Parse error before end of line
-file:3: error: Parse error before end of line
+file:1: error: syntax error in type comment
 
 [case testInvalidStringLiteralType2]
 def f(x:
       'A B'
       ) -> None: pass
 [out]
-file:2: error: Parse error before "B"
-file:3: error: Parse error before end of line
+file:1: error: syntax error in type comment
 
 [case testInvalidTypeComment]
 0
 x = 0 # type: A A
 [out]
-file:2: error: Parse error before "A"
+file:2: error: syntax error in type comment
 
 [case testInvalidTypeComment2]
 0
 x = 0 # type: A[
 [out]
-file:2: error: Parse error before end of line
+file:2: error: syntax error in type comment
 
 [case testInvalidTypeComment3]
 0
 x = 0 # type:
 [out]
-file:2: error: Empty type annotation
+file:2: error: syntax error in type comment
 
 [case testInvalidTypeComment4]
 0
 x = 0 # type: *
 [out]
-file:2: error: Parse error before end of line
+file:2: error: syntax error in type comment
 
 [case testInvalidMultilineLiteralType]
 def f() -> "A\nB": pass
 [out]
-file:1: error: Parse error before end of line
-
-[case testInvalidMetaclass]
-class A(metaclass=1): pass
-[out]
-file:1: error: Parse error before numeric literal
-file:1: error: Parse error before end of file
+file:1: error: syntax error in type comment
 
 [case testInvalidSignatureInComment1]
 def f(): # type: x
   pass
 [out]
-file:1: error: Parse error before "x"
+file:1: error: syntax error in type comment
 
 [case testInvalidSignatureInComment2]
 def f(): # type:
   pass
 [out]
-file:1: error: Empty type annotation
+file:1: error: syntax error in type comment
 
 [case testInvalidSignatureInComment3]
 def f(): # type: (
   pass
 [out]
-file:1: error: Parse error before end of line
+file:1: error: syntax error in type comment
 
 [case testInvalidSignatureInComment4]
 def f(): # type: (.
   pass
 [out]
-file:1: error: Parse error before .
+file:1: error: syntax error in type comment
 
 [case testInvalidSignatureInComment5]
 def f(): # type: (x
   pass
 [out]
-file:1: error: Parse error before end of line
+file:1: error: syntax error in type comment
 
 [case testInvalidSignatureInComment6]
 def f(): # type: (x)
   pass
 [out]
-file:1: error: Parse error before end of line
+file:1: error: syntax error in type comment
 
 [case testInvalidSignatureInComment7]
 def f(): # type: (x) -
   pass
 [out]
-file:1: error: Parse error before -
+file:1: error: syntax error in type comment
 
 [case testInvalidSignatureInComment8]
 def f(): # type: (x) ->
   pass
 [out]
-file:1: error: Parse error before end of line
+file:1: error: syntax error in type comment
 
 [case testInvalidSignatureInComment9]
 def f(): # type: (x) -> .
   pass
 [out]
-file:1: error: Parse error before .
+file:1: error: syntax error in type comment
 
 [case testInvalidSignatureInComment10]
 def f(): # type: (x) -> x x
   pass
 [out]
-file:1: error: Parse error before "x"
+file:1: error: syntax error in type comment
 
 [case testDuplicateSignatures1]
 def f() -> None: # type: () -> None
@@ -278,7 +250,8 @@ def f(x, y): # type: (X) -> z
 [out]
 file:1: error: Type signature has too few arguments
 
-[case testCommentFunctionAnnotationVarArgMispatch]
+[case testCommentFunctionAnnotationVarArgMispatch-skip]
+# see mypy issue #1997
 def f(x): # type: (*X) -> Y
     pass
 def g(*x): # type: (X) -> Y
@@ -287,203 +260,178 @@ def g(*x): # type: (X) -> Y
 file:1: error: Inconsistent use of '*' in function signature
 file:3: error: Inconsistent use of '*' in function signature
 
-[case testCommentFunctionAnnotationVarArgMispatch2]
+[case testCommentFunctionAnnotationVarArgMispatch2-skip]
+# see mypy issue #1997
 def f(*x, **y): # type: (**X, *Y) -> Z
     pass
 def g(*x, **y): # type: (*X, *Y) -> Z
     pass
 [out]
 file:1: error: Inconsistent use of '*' in function signature
-file:1: error: Inconsistent use of '**' in function signature
+file:3: error: syntax error in type comment
 file:3: error: Inconsistent use of '*' in function signature
 file:3: error: Inconsistent use of '**' in function signature
 
-[case testPrintStatementInPython3]
+[case testPrintStatementInPython3-skip]
 print 1
 [out]
-file:1: error: Parse error before numeric literal
+file:1: error: Missing parentheses in call to 'print'
 
 [case testInvalidConditionInConditionalExpression]
 1 if 2, 3 else 4
 [out]
-file:1: error: Parse error before ,
+file:1: error: invalid syntax
 
 [case testInvalidConditionInConditionalExpression2]
 1 if x for y in z else 4
 [out]
-file:1: error: Parse error before "for"
+file:1: error: invalid syntax
 
 [case testInvalidConditionInConditionalExpression2]
 1 if x else for y in z
 [out]
-file:1: error: Parse error before "for"
+file:1: error: invalid syntax
 
 [case testYieldFromNotRightParameter]
 def f():
     yield from
 [out]
-file:2: error: Parse error before end of line
+file:2: error: invalid syntax
 
 [case testYieldFromAfterReturn]
 def f():
     return yield from h()
 [out]
-file:2: error: Parse error before "yield"
+file:2: error: invalid syntax
 
 [case testImportDotModule]
 import .x
 [out]
-file:1: error: Parse error before .
+file:1: error: invalid syntax
 
 [case testImportDot]
 import .
 [out]
-file:1: error: Parse error before .
+file:1: error: invalid syntax
 
 [case testInvalidFunctionName]
 def while(): pass
 [out]
-file:1: error: Parse error before "while"
-file:1: error: Parse error before end of line
+file:1: error: invalid syntax
 
 [case testInvalidEllipsis1]
 ...0
 ..._
 ...a
 [out]
-file:1: error: Parse error before numeric literal
-file:2: error: Parse error before "_"
-file:3: error: Parse error before "a"
+file:1: error: invalid syntax
 
 [case testBlockStatementInSingleLineIf]
 if 1: if 2: pass
 [out]
-file:1: error: Parse error before "if"
+file:1: error: invalid syntax
 
 [case testBlockStatementInSingleLineIf2]
 if 1: while 2: pass
 [out]
-file:1: error: Parse error before "while"
+file:1: error: invalid syntax
 
 [case testBlockStatementInSingleLineIf3]
 if 1: for x in y: pass
 [out]
-file:1: error: Parse error before "for"
+file:1: error: invalid syntax
 
 [case testUnexpectedEllipsis]
 a = a...
 [out]
-file:1: error: Parse error before ...
-
-[case testFromFutureImportStar]
-from __future__ import *
-x = 1
-[out]
-file:1: error: Parse error before *
+file:1: error: invalid syntax
 
 [case testParseErrorBeforeUnicodeLiteral]
 x u'y'
 [out]
-file:1: error: Parse error before string literal
+file:1: error: invalid syntax
 
 [case testParseErrorInExtendedSlicing]
 x[:,
 [out]
-file:1: error: Parse error before end of line
+file:1: error: unexpected EOF while parsing
 
 [case testParseErrorInExtendedSlicing2]
 x[:,::
 [out]
-file:1: error: Parse error before end of line
+file:1: error: unexpected EOF while parsing
 
 [case testParseErrorInExtendedSlicing3]
 x[:,:
 [out]
-file:1: error: Parse error before end of line
+file:1: error: unexpected EOF while parsing
 
 [case testPython2OctalIntLiteralInPython3]
 0377
 [out]
-file:1: error: Invalid numeric literal
+file:1: error: invalid token
 
 [case testInvalidEncoding]
 # foo
 # coding: uft-8
 [out]
-file:2: error: Unknown encoding 'uft-8'
+file:0: error: unknown encoding: uft-8
 
 [case testInvalidEncoding2]
 # coding=Uft.8
 [out]
-file:1: error: Unknown encoding 'Uft.8'
+file:0: error: unknown encoding: Uft.8
 
 [case testInvalidEncoding3]
 #!/usr/bin python
 # vim: set fileencoding=uft8 :
 [out]
-file:2: error: Unknown encoding 'uft8'
+file:0: error: unknown encoding: uft8
 
 [case testDoubleEncoding]
 # coding: uft8
 # coding: utf8
 # The first coding cookie should be used and fail.
 [out]
-file:1: error: Unknown encoding 'uft8'
+file:0: error: unknown encoding: uft8
 
 [case testDoubleEncoding2]
 # Again the first cookie should be used and fail.
 # coding: uft8
 # coding: utf8
 [out]
-file:2: error: Unknown encoding 'uft8'
-
-[case testDoubleEncoding3]
-# If the third line were interpreted as a coding cookie, we'd get a
-# different error message.
-# coding: ascii
-á = 1
-[out]
-file:4: error: Unrecognized character
-
-[case testDoubleEncoding4]
-
-
-# coding: ascii
-á = 1
-[out]
-file:4: error: Unrecognized character
+file:0: error: unknown encoding: uft8
 
 [case testLongLiteralInPython3]
 2L
 0x2L
 [out]
-file:1: error: Invalid numeric literal
-file:2: error: Invalid numeric literal
+file:1: error: invalid syntax
 
 [case testPython2LegacyInequalityInPython3]
 1 <> 2
 [out]
-file:1: error: Parse error before >
+file:1: error: invalid syntax
 
 [case testLambdaInListComprehensionInPython3]
 ([ 0 for x in 1, 2 if 3 ])
 [out]
-file:1: error: Parse error before ,
+file:1: error: invalid syntax
 
 [case testTupleArgListInPython3]
 def f(x, (y, z)): pass
 [out]
-file:1: error: Tuples in argument lists only supported in Python 2 mode
+file:1: error: invalid syntax
 
 [case testBackquoteInPython3]
 `1 + 2`
 [out]
-file:1: error: Unrecognized character `
+file:1: error: invalid syntax
 
 [case testSmartQuotes]
 foo = ‘bar’
 [out]
-file:1: error: Unrecognized character
+file:1: error: invalid character in identifier
 
 [case testExceptCommaInPython3]
 try:
@@ -491,6 +439,10 @@ try:
 except KeyError, IndexError:
     pass
 [out]
-file:3: error: Parse error before ,
-file:3: error: Parse error before :
-file:4: error: Inconsistent indentation
+file:3: error: invalid syntax
+
+[case testLocalVarWithTypeOnNextLine]
+x = 0
+  # type: int
+[out]
+file:2: error: misplaced type annotation
diff --git a/test-data/unit/parse-python2.test b/test-data/unit/parse-python2.test
index 7d4931e028855..7abc157b955cd 100644
--- a/test-data/unit/parse-python2.test
+++ b/test-data/unit/parse-python2.test
@@ -109,7 +109,8 @@ MypyFile:1(
   ExpressionStmt:3(
     IntExpr(255)))
 
-[case testLongLiteral]
+[case testLongLiteral-skip]
+# see typed_ast issue #26
 0L
 123L
 012L
@@ -187,7 +188,7 @@ MypyFile:1(
     NameExpr(y)))
 
 [case testEllipsisInExpression_python2]
-x = ... # E: Parse error before ...
+x = ... # E: invalid syntax
 [out]
 
 [case testStrLiteralConcatenationWithMixedLiteralTypes]
@@ -333,28 +334,27 @@ MypyFile:1(
 [case testInvalidExprInTupleArgListInPython2_1]
 def f(x, ()): pass
 [out]
-main: error: Empty tuple not valid as an argument
+main:1: error: invalid syntax
 
 [case testInvalidExprInTupleArgListInPython2_2]
 def f(x, (y, x[1])): pass
 [out]
-main:1: error: Invalid item in tuple argument
+main:1: error: invalid syntax
 
 [case testListLiteralAsTupleArgInPython2]
 def f(x, [x]): pass
 [out]
-main:1: error: Parse error before [
-main:1: error: Parse error before end of line
+main:1: error: invalid syntax
 
 [case testTupleArgAfterStarArgInPython2]
 def f(*a, (b, c)): pass
 [out]
-main:1: error: Invalid argument list
+main:1: error: invalid syntax
 
 [case testTupleArgAfterStarStarArgInPython2]
 def f(*a, (b, c)): pass
 [out]
-main:1: error: Invalid argument list
+main:1: error: invalid syntax
 
 [case testParenthesizedArgumentInPython2]
 def f(x, (y)): pass
@@ -374,8 +374,8 @@ def f(a, (a, b)):
 def g((x, (x, y))):
     pass
 [out]
-main:1: error: Duplicate argument name "a"
-main:3: error: Duplicate argument name "x"
+main:1: error: duplicate argument 'a' in function definition
+main:3: error: duplicate argument 'x' in function definition
 
 [case testBackquotesInPython2]
 `1 + 2`
diff --git a/test-data/unit/parse.test b/test-data/unit/parse.test
index 0dec0f397281f..4335fffaa9389 100644
--- a/test-data/unit/parse.test
+++ b/test-data/unit/parse.test
@@ -109,8 +109,8 @@ MypyFile:1(
     StrExpr(foo))
   ExpressionStmt:3(
     StrExpr(foobar))
-  ExpressionStmt:4(
-    StrExpr(\nfoo\u000abar))
+  ExpressionStmt:5(
+    StrExpr(\u000afoo\u000abar))
   ExpressionStmt:6(
     StrExpr(fo''bar))
   ExpressionStmt:7(
@@ -119,8 +119,8 @@ MypyFile:1(
     StrExpr(foo))
   ExpressionStmt:9(
     StrExpr(foobar))
-  ExpressionStmt:10(
-    StrExpr(\nfoo\u000abar))
+  ExpressionStmt:11(
+    StrExpr(\u000afoo\u000abar))
   ExpressionStmt:12(
     StrExpr(fo""bar)))
 
@@ -130,9 +130,9 @@ r"x\n\""
 [out]
 MypyFile:1(
   ExpressionStmt:1(
-    StrExpr(x\n'))
+    StrExpr(x\n\'))
   ExpressionStmt:2(
-    StrExpr(x\n")))
+    StrExpr(x\n\")))
 --" fix syntax highlight
 
 [case testBytes]
@@ -147,7 +147,7 @@ MypyFile:1(
   ExpressionStmt:2(
     BytesExpr(foobar))
   ExpressionStmt:3(
-    BytesExpr(x\n')))
+    BytesExpr(x\\n\\')))
 
 [case testEscapesInStrings]
 '\r\n\t\x2f\u123f'
@@ -157,7 +157,7 @@ MypyFile:1(
   ExpressionStmt:1(
     StrExpr(\u000d\u000a\u0009/\u123f))
   ExpressionStmt:2(
-    BytesExpr(\u000d\u000a\u0009/\\u123f)))
+    BytesExpr(\r\n\t/\\\u123f)))
 -- Note \\u in the b'...' case (\u sequence not translated)
 
 [case testEscapedQuote]
@@ -176,7 +176,7 @@ MypyFile:1(
   ExpressionStmt:1(
     StrExpr(\u0000\u0001\u007fS4))
   ExpressionStmt:2(
-    BytesExpr(\u0001\u013e)))
+    BytesExpr(\x01>)))
 
 [case testUnicodeLiteralInPython3]
 u'foo'
@@ -301,19 +301,23 @@ MypyFile:1(
     Then(
       ExpressionStmt:2(
         IntExpr(2)))
-    If(
-      IntExpr(3))
-    Then(
-      ExpressionStmt:4(
-        IntExpr(4)))
-    If(
-      IntExpr(5))
-    Then(
-      ExpressionStmt:6(
-        IntExpr(6)))
     Else(
-      ExpressionStmt:8(
-        IntExpr(7)))))
+      IfStmt:3(
+        If(
+          IntExpr(3))
+        Then(
+          ExpressionStmt:4(
+            IntExpr(4)))
+        Else(
+          IfStmt:5(
+            If(
+              IntExpr(5))
+            Then(
+              ExpressionStmt:6(
+                IntExpr(6)))
+            Else(
+              ExpressionStmt:8(
+                IntExpr(7)))))))))
 
 [case testWhile]
 while 1:
@@ -432,16 +436,6 @@ MypyFile:1(
         NameExpr(None)
         Any?))))
 
-[case testLocalVarWithTypeOnNextLine]
-x = 0
-  # type: int
-[out]
-MypyFile:1(
-  AssignmentStmt:1(
-    NameExpr(x)
-    IntExpr(0)
-    int?))
-
 [case testFunctionDefWithType]
 def f(y: str) -> int:
   return
@@ -948,18 +942,6 @@ MypyFile:1(
       NameExpr(x)
       NameExpr(y))))
 
-[case testNotAsRightOperand]
-x in not y
-[out]
-MypyFile:1(
-  ExpressionStmt:1(
-    ComparisonExpr:1(
-      in
-      NameExpr(x)
-      UnaryExpr:1(
-        not
-        NameExpr(y)))))
-
 [case testNotIn]
 x not in y
 not x not in y
@@ -988,12 +970,15 @@ MypyFile:1(
         NameExpr(z)))))
 
 [case testNotAsBinaryOp]
-x not y # E: Parse error before "y"
-x not is y # E: Parse error before is
+x not y # E: invalid syntax
+[out]
+
+[case testNotIs]
+x not is y # E: invalid syntax
 [out]
 
 [case testBinaryNegAsBinaryOp]
-1 ~ 2 # E: Parse error before ~
+1 ~ 2 # E: invalid syntax
 [out]
 
 [case testDictionaryExpression]
@@ -1188,7 +1173,7 @@ MypyFile:1(
         IntExpr(3)))))
 
 [case testGeneratorExpression]
-x for y in z
+(x for y in z)
 [out]
 MypyFile:1(
   ExpressionStmt:1(
@@ -1198,7 +1183,7 @@ MypyFile:1(
       NameExpr(z))))
 
 [case testGeneratorExpressionNested]
-x for y, (p, q) in z
+(x for y, (p, q) in z)
 [out]
 MypyFile:1(
   ExpressionStmt:1(
@@ -1265,25 +1250,25 @@ MypyFile:1(
   ExpressionStmt:1(
     IndexExpr:1(
       NameExpr(x)
-      SliceExpr:1(
+      SliceExpr:-1(
         IntExpr(1)
         IntExpr(2))))
   ExpressionStmt:2(
     IndexExpr:2(
       NameExpr(x)
-      SliceExpr:2(
+      SliceExpr:-1(
         <empty>
         IntExpr(1))))
   ExpressionStmt:3(
     IndexExpr:3(
       NameExpr(x)
-      SliceExpr:3(
+      SliceExpr:-1(
         IntExpr(1)
         <empty>)))
   ExpressionStmt:4(
     IndexExpr:4(
       NameExpr(x)
-      SliceExpr:4(
+      SliceExpr:-1(
         <empty>
         <empty>))))
 
@@ -1298,35 +1283,35 @@ MypyFile:1(
   ExpressionStmt:1(
     IndexExpr:1(
       NameExpr(x)
-      SliceExpr:1(
+      SliceExpr:-1(
         IntExpr(1)
         IntExpr(2)
         IntExpr(3))))
   ExpressionStmt:2(
     IndexExpr:2(
       NameExpr(x)
-      SliceExpr:2(
+      SliceExpr:-1(
         IntExpr(1)
         <empty>
         IntExpr(2))))
   ExpressionStmt:3(
     IndexExpr:3(
       NameExpr(x)
-      SliceExpr:3(
+      SliceExpr:-1(
         <empty>
         IntExpr(1)
         IntExpr(2))))
   ExpressionStmt:4(
     IndexExpr:4(
       NameExpr(x)
-      SliceExpr:4(
+      SliceExpr:-1(
         <empty>
         <empty>
         IntExpr(2))))
   ExpressionStmt:5(
     IndexExpr:5(
       NameExpr(x)
-      SliceExpr:5(
+      SliceExpr:-1(
         IntExpr(1)
         IntExpr(2)))))
 
@@ -1541,7 +1526,7 @@ MypyFile:1(
       PassStmt:2())))
 
 [case testGeneratorWithCondition]
-x for y in z if 0
+(x for y in z if 0)
 [out]
 MypyFile:1(
   ExpressionStmt:1(
@@ -2967,9 +2952,9 @@ MypyFile:1(
       PassStmt:8())))
 
 [case testStarExprInGeneratorExpr]
-x for y, *p in z
-x for *p, y in z
-x for y, *p, q in z
+(x for y, *p in z)
+(x for *p, y in z)
+(x for y, *p, q in z)
 [out]
 MypyFile:1(
   ExpressionStmt:1(
@@ -3034,7 +3019,7 @@ MypyFile:1(
       __class__)))
 
 [case testFunctionWithManyKindsOfArgs]
-def f(x, *args, *, y=None, **kw): pass
+def f(x, *args,  y=None, **kw): pass
 [out]
 MypyFile:1(
   FuncDef:1(
@@ -3145,10 +3130,10 @@ MypyFile:1(
       NameExpr(f)
       Args(
         NameExpr(y))
+      VarArg
       KwArgs(
         x
-        IntExpr(1))
-      VarArg)))
+        IntExpr(1)))))
 
 [case testConditionalExpressionInSetComprehension]
 { 1 if x else 2 for x in y }
@@ -3214,11 +3199,11 @@ MypyFile:1(
   ExpressionStmt:1(
     IndexExpr:1(
       NameExpr(a)
-      TupleExpr:1(
-        SliceExpr:1(
+      TupleExpr:-1(
+        SliceExpr:-1(
           <empty>
           <empty>)
-        SliceExpr:1(
+        SliceExpr:-1(
           <empty>
           <empty>)))))
 
@@ -3229,11 +3214,11 @@ MypyFile:1(
   ExpressionStmt:1(
     IndexExpr:1(
       NameExpr(a)
-      TupleExpr:1(
-        SliceExpr:1(
+      TupleExpr:-1(
+        SliceExpr:-1(
           IntExpr(1)
           IntExpr(2))
-        SliceExpr:1(
+        SliceExpr:-1(
           <empty>
           <empty>)))))
 
@@ -3244,8 +3229,8 @@ MypyFile:1(
   ExpressionStmt:1(
     IndexExpr:1(
       NameExpr(a)
-      TupleExpr:1(
-        SliceExpr:1(
+      TupleExpr:-1(
+        SliceExpr:-1(
           IntExpr(1)
           IntExpr(2)
           IntExpr(3))
diff --git a/test-data/unit/python2eval.test b/test-data/unit/python2eval.test
index 12fa5a62aea4f..b750de8b12a13 100644
--- a/test-data/unit/python2eval.test
+++ b/test-data/unit/python2eval.test
@@ -152,13 +152,14 @@ f(**params)
 
 [case testFromFutureImportUnicodeLiterals2_python2]
 from __future__ import unicode_literals
-def f(x: str) -> None: pass
+def f(x): # type: (str) -> None
+  pass
 f(b'')
 f(u'')
 f('')
 [out]
-_program.py:4: error: Argument 1 to "f" has incompatible type "unicode"; expected "str"
 _program.py:5: error: Argument 1 to "f" has incompatible type "unicode"; expected "str"
+_program.py:6: error: Argument 1 to "f" has incompatible type "unicode"; expected "str"
 
 [case testStrUnicodeCompatibility_python2]
 import typing
@@ -391,9 +392,11 @@ f(b'')
 [file m.pyi]
 from typing import overload
 @overload
-def f(x: unicode) -> int: pass
+def f(x): # type: (unicode) -> int
+  pass
 @overload
-def f(x: bytearray) -> int: pass
+def f(x): # type: (bytearray) -> int
+  pass
 [out]
 _program.py:2: error: No overload variant of "f" matches argument types [builtins.int]
 
@@ -465,7 +468,7 @@ re.subn(upat, lambda m: u'', u'')[0] + u''
 
 [case testYieldRegressionTypingAwaitable_python2]
 # Make sure we don't reference typing.Awaitable in Python 2 mode.
-def g() -> int:
+def g():  # type: () -> int
     yield
 [out]
 _program.py:2: error: The return type of a generator function should be "Generator" or one of its supertypes
diff --git a/test-data/unit/semanal-classes.test b/test-data/unit/semanal-classes.test
index 431261fa3a182..a99f8511ad0c6 100644
--- a/test-data/unit/semanal-classes.test
+++ b/test-data/unit/semanal-classes.test
@@ -550,7 +550,7 @@ class A(None): pass
 class B(Any): pass
 class C(Callable[[], int]): pass
 [out]
-main:2: error: Invalid base class
+main: error: Invalid base class
 main:4: error: Invalid base class
 
 [case testTupleAsBaseClass]
diff --git a/test-data/unit/semanal-errors.test b/test-data/unit/semanal-errors.test
index 3d3a777a8ec72..ce4e684326223 100644
--- a/test-data/unit/semanal-errors.test
+++ b/test-data/unit/semanal-errors.test
@@ -1,11 +1,3 @@
-[case testPropagatingParseErrors]
-in 1
-def f():
-  1 1
-[out]
-main:1: error: Parse error before in
-main:3: error: Parse error before numeric literal
-
 [case testUndefinedVariableInGlobalStatement]
 import typing
 x
@@ -95,8 +87,8 @@ from typing import overload
 class A: pass
 @overload
 def f(): pass
-@overload
-def f(x: A[int]) -> None: pass # E: "A" expects no type arguments, but 1 given
+@overload # E: "A" expects no type arguments, but 1 given
+def f(x: A[int]) -> None: pass
 [out]
 
 [case testInvalidNumberOfGenericArgsInBaseType]
@@ -367,47 +359,78 @@ yield
 main:1: error: 'yield' outside function
 main:2: error: 'yield' outside function
 
-[case testInvalidLvalues]
+[case testInvalidLvalues1]
 1 = 1
+[out]
+main:1: error: can't assign to literal
+
+[case testInvalidLvalues2]
 (1) = 1
+[out]
+main:1: error: can't assign to literal
+
+[case testInvalidLvalues3]
 (1, 1) = 1
+[out]
+main:1: error: can't assign to literal
+
+[case testInvalidLvalues4]
 [1, 1] = 1
+[out]
+main:1: error: can't assign to literal
+
+[case testInvalidLvalues5]
 () = 1
 [out]
-main:1: error: Invalid assignment target
-main:2: error: Invalid assignment target
-main:3: error: Invalid assignment target
-main:4: error: Invalid assignment target
-main:5: error: Can't assign to ()
---' (hack to fix syntax highlighting)
+main:1: error: can't assign to ()
 
-[case testInvalidLvalues2]
-x = y = z = 1
+[case testInvalidLvalues6]
+x = y = z = 1  # ok
 x, (y, 1) = 1
+[out]
+main:2: error: can't assign to literal
+
+[case testInvalidLvalues7]
 x, [y, 1] = 1
+[out]
+main:1: error: can't assign to literal
+
+[case testInvalidLvalues8]
 x, [y, [z, 1]] = 1
-x, (y, (z, 1)) = 1
+[out]
+main:1: error: can't assign to literal
+
+[case testInvalidLvalues9]
 x, (y) = 1 # ok
 x, (y, (z, z)) = 1 # ok
+x, (y, (z, 1)) = 1
 [out]
-main:2: error: Invalid assignment target
-main:3: error: Invalid assignment target
-main:4: error: Invalid assignment target
-main:5: error: Invalid assignment target
+main:3: error: can't assign to literal
 
-[case testInvalidLvalues3]
-x = 1
+[case testInvalidLvalues10]
 x + x = 1
+[out]
+main:1: error: can't assign to operator
+
+[case testInvalidLvalues11]
 -x = 1
+[out]
+main:1: error: can't assign to operator
+
+[case testInvalidLvalues12]
 1.1 = 1
+[out]
+main:1: error: can't assign to literal
+
+[case testInvalidLvalues13]
 'x' = 1
+[out]
+main:1: error: can't assign to literal
+
+[case testInvalidLvalues14]
 x() = 1
 [out]
-main:2: error: Invalid assignment target
-main:3: error: Invalid assignment target
-main:4: error: Invalid assignment target
-main:5: error: Invalid assignment target
-main:6: error: Invalid assignment target
+main:1: error: can't assign to function call
 
 [case testTwoStarExpressions]
 a, *b, *c = 1
@@ -457,11 +480,17 @@ a = 1
 [out]
 main:2: error: Can use starred expression only as assignment target
 
-[case testInvalidDel]
-import typing
+[case testInvalidDel1]
+x = 1
+del x(1)  # E: can't delete function call
+[out]
+
+[case testInvalidDel2]
 x = 1
-del x(1)  # E: Invalid delete target
-del x + 1 # E: Invalid delete target
+del x + 1 # E: can't delete operator
+[out]
+
+[case testInvalidDel3]
 del z     # E: Name 'z' is not defined
 [out]
 
@@ -820,7 +849,7 @@ import typing
 def f(): pass
 f() = 1 # type: int
 [out]
-main:3: error: Invalid assignment target
+main:3: error: can't assign to function call
 
 [case testIndexedAssignmentWithTypeDeclaration]
 import typing
@@ -886,10 +915,14 @@ x, y = 1, 2 # type: int # E: Tuple type expected for multiple variables
 
 [case testInvalidLvalueWithExplicitType]
 a = 1
+a() = None # type: int  # E: can't assign to function call
+[out]
+
+[case testInvalidLvalueWithExplicitType2]
+a = 1
 a[1] = None # type: int # E: Unexpected type declaration
 a.x = None # type: int \
     # E: Type cannot be declared in assignment to non-self attribute
-a() = None # type: int  # E: Invalid assignment target
 [out]
 
 [case testInvalidLvalueWithExplicitType3]
@@ -1028,7 +1061,7 @@ def f(x: 'foo'): pass # E: Name 'foo' is not defined
 [out]
 
 [case testInvalidStrLiteralType2]
-def f(x: 'int['): pass # E: Parse error before end of line
+def f(x: 'int['): pass # E: syntax error in type comment
 [out]
 
 [case testInconsistentOverload]
@@ -1200,7 +1233,7 @@ main:1: note: (Did you mean 'typing.Callable'?)
 
 [case testInvalidWithTarget]
 def f(): pass
-with f() as 1: pass  # E: Invalid assignment target
+with f() as 1: pass  # E: can't assign to literal
 [out]
 
 [case testUseObsoleteNameForTypeVar]
@@ -1235,7 +1268,7 @@ import typing
 def f() -> None:
     f() = 1  # type: int
 [out]
-main:3: error: Invalid assignment target
+main:3: error: can't assign to function call
 
 [case testInvalidReferenceToAttributeOfOuterClass]
 class A:
diff --git a/test-data/unit/semanal-expressions.test b/test-data/unit/semanal-expressions.test
index 7c5728b01f373..cec2a3cc01106 100644
--- a/test-data/unit/semanal-expressions.test
+++ b/test-data/unit/semanal-expressions.test
@@ -115,20 +115,20 @@ MypyFile:1(
   ExpressionStmt:2(
     IndexExpr:2(
       NameExpr(x [__main__.x])
-      SliceExpr:2(
+      SliceExpr:-1(
         NameExpr(y [__main__.y])
         NameExpr(z [__main__.z])
         NameExpr(x [__main__.x]))))
   ExpressionStmt:3(
     IndexExpr:3(
       NameExpr(x [__main__.x])
-      SliceExpr:3(
+      SliceExpr:-1(
         <empty>
         <empty>)))
   ExpressionStmt:4(
     IndexExpr:4(
       NameExpr(x [__main__.x])
-      SliceExpr:4(
+      SliceExpr:-1(
         <empty>
         NameExpr(y [__main__.y])))))
 
@@ -309,7 +309,7 @@ MypyFile:1(
 
 [case testGeneratorExpression]
 a = 0
-x for x in a
+(x for x in a)
 [out]
 MypyFile:1(
   AssignmentStmt:1(
@@ -323,7 +323,7 @@ MypyFile:1(
 
 [case testGeneratorExpressionNestedIndex]
 a = 0
-x for x, (y, z) in a
+(x for x, (y, z) in a)
 [out]
 MypyFile:1(
   AssignmentStmt:1(
diff --git a/test-data/unit/semanal-statements.test b/test-data/unit/semanal-statements.test
index 8825c8ead7e6c..e104ab75afab3 100644
--- a/test-data/unit/semanal-statements.test
+++ b/test-data/unit/semanal-statements.test
@@ -278,19 +278,23 @@ MypyFile:1(
     Then(
       ExpressionStmt:3(
         NameExpr(x [__main__.x])))
-    If(
-      NameExpr(x [__main__.x]))
-    Then(
-      ExpressionStmt:5(
-        NameExpr(x [__main__.x])))
-    If(
-      NameExpr(x [__main__.x]))
-    Then(
-      ExpressionStmt:7(
-        NameExpr(x [__main__.x])))
     Else(
-      ExpressionStmt:9(
-        NameExpr(x [__main__.x])))))
+      IfStmt:4(
+        If(
+          NameExpr(x [__main__.x]))
+        Then(
+          ExpressionStmt:5(
+            NameExpr(x [__main__.x])))
+        Else(
+          IfStmt:6(
+            If(
+              NameExpr(x [__main__.x]))
+            Then(
+              ExpressionStmt:7(
+                NameExpr(x [__main__.x])))
+            Else(
+              ExpressionStmt:9(
+                NameExpr(x [__main__.x])))))))))
 
 [case testSimpleIf]
 if object:
@@ -537,7 +541,7 @@ MypyFile:1(
 def f(x, y) -> None:
     del x, y + 1
 [out]
-main:2: error: Invalid delete target
+main:2: error: can't delete operator
 
 [case testTry]
 class c: pass