Revert "Add a Str() function to gclient for use in DEPS files."

This reverts commit c7eed83f96.

Reason for revert: I'm getting reports of internal iOS checkouts being broken. Reverting while I reproduce / debug it.

Original change's description:
> Add a Str() function to gclient for use in DEPS files.
> 
> gclient's existing functionality for handling variables is
> ambiguous: the value of a variable can either be a string literal
> or an expression fragment. The implementation is required to
> parse a value as an expression, and, if it is legal, treat it
> as an expression instead of a literal. This means that
> 
>   gclient_gn_args_file = 'src/build/args.gni'
>   gclient_gn_args = ['xcode_version']
>   vars = {
>     'xcode_version': 'xcode-12'
>   }
> 
> would cause a problem because gclient would try to parse the
> variable as an expression, and 'xcode' would not be defined.
> 
> This patch adds a workaround for this, where you can instead
> use the Str() function to explicitly tell gclient to treat the
> value as a string and not a potential expression.
> 
> The above example would be changed to:
> 
>   gclient_gn_args_file = 'src/build/args.gni'
>   gclient_gn_args = ['xcode_version']
>   vars = {
>     'xcode_version': Str('xcode-12')
>   }
> 
> The variable may still be used in every context where it was legal
> to be used before.
> 
> Bug: 1099242
> 
> Change-Id: Ic2a17eea5f7098113bdba0557fe29e1a931a74b8
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2268406
> Reviewed-by: Ben Pastene <bpastene@chromium.org>
> Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
> Commit-Queue: Dirk Pranke <dpranke@google.com>

TBR=thakis@chromium.org,dpranke@google.com,ehmaldonado@chromium.org,bpastene@chromium.org,apolito@google.com,infra-scoped@luci-project-accounts.iam.gserviceaccount.com

Change-Id: Iac2b003f32acdbca15a19f821b61423e34b3466c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1099242
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2273978
Reviewed-by: Dirk Pranke <dpranke@google.com>
Commit-Queue: Dirk Pranke <dpranke@google.com>

gclient.py

@@ -1043,9 +1043,7 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
     variables = self.get_vars()
     for arg in self._gn_args:
       value = variables[arg]
-      if isinstance(value, gclient_eval.ConstantString):
-        value = value.value
-      elif isinstance(value, basestring):
+      if isinstance(value, basestring):
         value = gclient_eval.EvaluateCondition(value, variables)
       lines.append('%s = %s' % (arg, ToGNString(value)))
     with open(os.path.join(self.root.root_dir, self._gn_args_file), 'wb') as f:
@@ -1267,11 +1265,11 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
     result = {}
     result.update(self._vars)
     if self.parent:
-      merge_vars(result, self.parent.get_vars())
+      parent_vars = self.parent.get_vars()
+      result.update(parent_vars)
     # Provide some built-in variables.
     result.update(self.get_builtin_vars())
-    merge_vars(result, self.custom_vars)
-
+    result.update(self.custom_vars or {})
     return result
 
 
@@ -1285,18 +1283,6 @@ _PLATFORM_MAPPING = {
 }
 
 
-def merge_vars(result, new_vars):
-  for k, v in new_vars.items():
-    if (k in result and
-        isinstance(result[k], gclient_eval.ConstantString)):
-      if isinstance(v, gclient_eval.ConstantString):
-        result[k].value = v.value
-      else:
-        result[k].value = v
-    else:
-      result.setdefault(k, v)
-
-
 def _detect_host_os():
   return _PLATFORM_MAPPING[sys.platform]
 

gclient_eval.py

@@ -24,27 +24,6 @@ else:
   basestring = str
 
 
-class ConstantString(object):
-  def __init__(self, value):
-    self.value = value
-
-  def __format__(self, format_spec):
-    del format_spec
-    return self.value
-
-  def __repr__(self):
-    return "Str('" + self.value + "')"
-
-  def __eq__(self, other):
-    if isinstance(other, ConstantString):
-      return self.value == other.value
-    else:
-      return self.value == other
-
-  def __hash__(self):
-      return self.value.__hash__()
-
-
 class _NodeDict(collections_abc.MutableMapping):
   """Dict-like type that also stores information on AST nodes and tokens."""
   def __init__(self, data=None, tokens=None):
@@ -135,7 +114,7 @@ _GCLIENT_DEPS_SCHEMA = _NodeDictSchema({
 _GCLIENT_HOOKS_SCHEMA = [
     _NodeDictSchema({
         # Hook action: list of command-line arguments to invoke.
-        'action': [schema.Or(basestring)],
+        'action': [basestring],
 
         # Name of the hook. Doesn't affect operation.
         schema.Optional('name'): basestring,
@@ -241,9 +220,7 @@ _GCLIENT_SCHEMA = schema.Schema(
 
         # Variables that can be referenced using Var() - see 'deps'.
         schema.Optional('vars'): _NodeDictSchema({
-            schema.Optional(basestring): schema.Or(ConstantString,
-                                                   basestring,
-                                                   bool),
+            schema.Optional(basestring): schema.Or(basestring, bool),
         }),
     }))
 
@@ -251,8 +228,6 @@ _GCLIENT_SCHEMA = schema.Schema(
 def _gclient_eval(node_or_string, filename='<unknown>', vars_dict=None):
   """Safely evaluates a single expression. Returns the result."""
   _allowed_names = {'None': None, 'True': True, 'False': False}
-  if isinstance(node_or_string, ConstantString):
-    return node_or_string.value
   if isinstance(node_or_string, basestring):
     node_or_string = ast.parse(node_or_string, filename=filename, mode='eval')
   if isinstance(node_or_string, ast.Expression):
@@ -294,23 +269,16 @@ def _gclient_eval(node_or_string, filename='<unknown>', vars_dict=None):
         node, ast.NameConstant):  # Since Python 3.4
       return node.value
     elif isinstance(node, ast.Call):
-      if (not isinstance(node.func, ast.Name) or
-          (node.func.id not in ('Str', 'Var'))):
+      if not isinstance(node.func, ast.Name) or node.func.id != 'Var':
         raise ValueError(
-            'Str and Var are the only allowed functions (file %r, line %s)' % (
+            'Var is the only allowed function (file %r, line %s)' % (
                 filename, getattr(node, 'lineno', '<unknown>')))
       if node.keywords or getattr(node, 'starargs', None) or getattr(
           node, 'kwargs', None) or len(node.args) != 1:
         raise ValueError(
-            '%s takes exactly one argument (file %r, line %s)' % (
-                node.func.id, filename, getattr(node, 'lineno', '<unknown>')))
-      if node.func.id == 'Str':
-        if isinstance(node.args[0], ast.Str):
-          return ConstantString(node.args[0].s)
-        raise ValueError('Passed a non-string to Str() (file %r, line%s)' % (
-            filename, getattr(node, 'lineno', '<unknown>')))
-      else:
-        arg = _convert(node.args[0])
+            'Var takes exactly one argument (file %r, line %s)' % (
+                filename, getattr(node, 'lineno', '<unknown>')))
+      arg = _convert(node.args[0])
       if not isinstance(arg, basestring):
         raise ValueError(
             'Var\'s argument must be a variable name (file %r, line %s)' % (
@@ -322,10 +290,7 @@ def _gclient_eval(node_or_string, filename='<unknown>', vars_dict=None):
             '%s was used as a variable, but was not declared in the vars dict '
             '(file %r, line %s)' % (
                 arg, filename, getattr(node, 'lineno', '<unknown>')))
-      val = vars_dict[arg]
-      if isinstance(val, ConstantString):
-        val = val.value
-      return val
+      return vars_dict[arg]
     elif isinstance(node, ast.BinOp) and isinstance(node.op, ast.Add):
       return _convert(node.left) + _convert(node.right)
     elif isinstance(node, ast.BinOp) and isinstance(node.op, ast.Mod):
@@ -636,8 +601,6 @@ def RenderDEPSFile(gclient_dict):
 
 
 def _UpdateAstString(tokens, node, value):
-  if isinstance(node, ast.Call):
-    node = node.args[0]
   position = node.lineno, node.col_offset
   quote_char = ''
   if isinstance(node, ast.Str):
@@ -847,10 +810,7 @@ def GetVar(gclient_dict, var_name):
     raise KeyError(
         "Could not find any variable called %s." % var_name)
 
-  val = gclient_dict['vars'][var_name]
-  if isinstance(val, ConstantString):
-    return val.value
-  return val
+  return gclient_dict['vars'][var_name]
 
 
 def GetCIPD(gclient_dict, dep_name, package_name):

tests/gclient_eval_unittest.py

@@ -47,28 +47,17 @@ class GClientEvalTest(unittest.TestCase):
   def test_invalid_call(self):
     with self.assertRaises(ValueError) as cm:
       gclient_eval._gclient_eval('Foo("bar")')
-    self.assertIn('Str and Var are the only allowed functions',
-                  str(cm.exception))
+    self.assertIn('Var is the only allowed function', str(cm.exception))
 
   def test_expands_vars(self):
     self.assertEqual(
         'foo',
         gclient_eval._gclient_eval('Var("bar")', vars_dict={'bar': 'foo'}))
-    self.assertEqual(
-        'baz',
-        gclient_eval._gclient_eval(
-            'Var("bar")',
-            vars_dict={'bar': gclient_eval.ConstantString('baz')}))
 
   def test_expands_vars_with_braces(self):
     self.assertEqual(
         'foo',
         gclient_eval._gclient_eval('"{bar}"', vars_dict={'bar': 'foo'}))
-    self.assertEqual(
-        'baz',
-        gclient_eval._gclient_eval(
-            '"{bar}"',
-            vars_dict={'bar': gclient_eval.ConstantString('baz')}))
 
   def test_invalid_var(self):
     with self.assertRaises(KeyError) as cm:
@@ -129,33 +118,28 @@ class ExecTest(unittest.TestCase):
     local_scope = gclient_eval.Exec('\n'.join([
         'vars = {',
         '  "foo": "bar",',
-        '  "baz": Str("quux")',
         '}',
         'deps = {',
-        '  "a_dep": "a" + Var("foo") + "b" + Var("baz"),',
+        '  "a_dep": "a" + Var("foo") + "b",',
         '}',
     ]))
-    Str = gclient_eval.ConstantString
     self.assertEqual({
-        'vars': {'foo': 'bar', 'baz': Str('quux')},
-        'deps': {'a_dep': 'abarbquux'},
+        'vars': collections.OrderedDict([('foo', 'bar')]),
+        'deps': collections.OrderedDict([('a_dep', 'abarb')]),
     }, local_scope)
 
   def test_braces_var(self):
     local_scope = gclient_eval.Exec('\n'.join([
         'vars = {',
         '  "foo": "bar",',
-        '  "baz": Str("quux")',
         '}',
         'deps = {',
-        '  "a_dep": "a{foo}b{baz}",',
+        '  "a_dep": "a{foo}b",',
         '}',
     ]))
-    Str = gclient_eval.ConstantString
     self.assertEqual({
-        'vars': {'foo': 'bar',
-                 'baz': Str('quux')},
-        'deps': {'a_dep': 'abarbquux'},
+        'vars': collections.OrderedDict([('foo', 'bar')]),
+        'deps': collections.OrderedDict([('a_dep', 'abarb')]),
     }, local_scope)
 
   def test_empty_deps(self):
@@ -166,17 +150,14 @@ class ExecTest(unittest.TestCase):
     local_scope = gclient_eval.Exec('\n'.join([
         'vars = {',
         '  "foo": "bar",',
-        '  "quux": Str("quuz")',
         '}',
         'deps = {',
         '  "a_dep": "a{foo}b",',
-        '  "b_dep": "c{quux}d",',
         '}',
-    ]), vars_override={'foo': 'baz', 'quux': 'corge'})
-    Str = gclient_eval.ConstantString
+    ]), vars_override={'foo': 'baz'})
     self.assertEqual({
-        'vars': {'foo': 'bar', 'quux': Str('quuz')},
-        'deps': {'a_dep': 'abazb', 'b_dep': 'ccorged'},
+        'vars': collections.OrderedDict([('foo', 'bar')]),
+        'deps': collections.OrderedDict([('a_dep', 'abazb')]),
     }, local_scope)
 
   def test_doesnt_override_undeclared_vars(self):
@@ -356,15 +337,6 @@ class EvaluateConditionTest(unittest.TestCase):
       gclient_eval.EvaluateCondition('(foo,) == "bar"', {'foo': 'bar'})
     self.assertIn('unexpected AST node', str(cm.exception))
 
-  def test_str_in_condition(self):
-    Str = gclient_eval.ConstantString
-    self.assertTrue(gclient_eval.EvaluateCondition(
-        's_var == "foo"',
-        {'s_var': Str("foo")}))
-
-    self.assertFalse(gclient_eval.EvaluateCondition(
-        's_var in ("baz", "quux")',
-        {'s_var': Str("foo")}))
 
 class VarTest(unittest.TestCase):
   def assert_adds_var(self, before, after):
@@ -410,23 +382,18 @@ class VarTest(unittest.TestCase):
     local_scope = gclient_eval.Exec('\n'.join([
         'vars = {',
         '  "foo": "bar",',
-        '  "quux": Str("quuz")',
         '}',
     ]))
 
-    self.assertEqual(gclient_eval.GetVar(local_scope, 'foo'),
-                     "bar")
-    self.assertEqual(gclient_eval.GetVar(local_scope, 'quux'),
-                     "quuz")
+    result = gclient_eval.GetVar(local_scope, 'foo')
+    self.assertEqual(result, "bar")
 
     gclient_eval.SetVar(local_scope, 'foo', 'baz')
-    gclient_eval.SetVar(local_scope, 'quux', 'corge')
     result = gclient_eval.RenderDEPSFile(local_scope)
 
     self.assertEqual(result, '\n'.join([
         'vars = {',
         '  "foo": "baz",',
-        '  "quux": Str("corge")',
         '}',
     ]))
 

tests/gclient_test.py

@@ -667,42 +667,6 @@ class GclientTest(trial_dir.TestCase):
         ('foo/skip2', None),
     ], [(dep.name, dep.url) for dep in sol.dependencies])
 
-  def testVarOverrides(self):
-    """Verifies expected behavior of variable overrides."""
-    write(
-        '.gclient',
-        'solutions = [\n'
-        '  { "name": "foo",\n'
-        '    "url": "svn://example.com/foo",\n'
-        '    "custom_vars": {\n'
-        '      "path": "c-d",\n'
-        '    },\n'
-        '  },]\n')
-    write(
-        os.path.join('foo', 'DEPS'),
-        'vars = {\n'
-        '  "path": Str("a-b"),\n'
-        '}\n'
-        'deps = {\n'
-        '  "foo/bar": "svn://example.com/foo/" + Var("path"),\n'
-        '}')
-    parser = gclient.OptionParser()
-    options, _ = parser.parse_args(['--jobs', '1'])
-
-    obj = gclient.GClient.LoadCurrentConfig(options)
-    obj.RunOnDeps('None', [])
-
-    sol = obj.dependencies[0]
-    self.assertEqual([
-        ('foo', 'svn://example.com/foo'),
-        ('foo/bar', 'svn://example.com/foo/c-d'),
-    ], self._get_processed())
-
-    self.assertEqual(1, len(sol.dependencies))
-    self.assertEqual([
-        ('foo/bar', 'svn://example.com/foo/c-d'),
-    ], [(dep.name, dep.url) for dep in sol.dependencies])
-
   def testDepsOsOverrideDepsInDepsFile(self):
     """Verifies that a 'deps_os' path cannot override a 'deps' path. Also
     see testUpdateWithOsDeps above.