Don't have newly added files trigger a coarse-grained rebuild in fine-grained cache mode

mypy/build.py

@@ -588,6 +588,7 @@ def __init__(self, data_dir: str,
         self.data_dir = data_dir
         self.errors = errors
         self.errors.set_ignore_prefix(ignore_prefix)
+        self.only_load_from_cache = options.use_fine_grained_cache
         self.lib_path = tuple(lib_path)
         self.source_set = source_set
         self.reports = reports
@@ -1674,6 +1675,13 @@ def __init__(self,
                                  for id, line in zip(self.meta.dependencies, self.meta.dep_lines)}
             self.child_modules = set(self.meta.child_modules)
         else:
+            # In fine-grained cache mode, pretend we only know about modules that
+            # have cache information and defer handling new modules until the
+            # fine-grained update.
+            if manager.only_load_from_cache:
+                manager.log("Deferring module to fine-grained update %s (%s)" % (path, id))
+                raise ModuleNotFound
+
             # Parse the file (and then some) to get the dependencies.
             self.parse_file()
             self.compute_dependencies()
@@ -2093,6 +2101,15 @@ def dispatch(sources: List[BuildSource], manager: BuildManager) -> Graph:
     manager.log("Mypy version %s" % __version__)
     t0 = time.time()
     graph = load_graph(sources, manager)
+
+    # This is a kind of unfortunate hack to work around some of fine-grained's
+    # fragility: if we have loaded less than 50% of the specified files from
+    # cache in fine-grained cache mode, load the graph again honestly.
+    if manager.options.use_fine_grained_cache and len(graph) < 0.50 * len(sources):
+        manager.log("Redoing load_graph because too much was missing")
+        manager.only_load_from_cache = False
+        graph = load_graph(sources, manager)
+
     t1 = time.time()
     manager.add_stats(graph_size=len(graph),
                       stubs_found=sum(g.path is not None and g.path.endswith('.pyi')
@@ -2206,7 +2223,7 @@ def load_graph(sources: List[BuildSource], manager: BuildManager,
     there are syntax errors.
     """
 
-    graph = old_graph or {}  # type: Graph
+    graph = old_graph if old_graph is not None else {}  # type: Graph
 
     # The deque is used to implement breadth-first traversal.
     # TODO: Consider whether to go depth-first instead.  This may

mypy/server/update.py

@@ -174,6 +174,7 @@ def __init__(self,
         # this directly reflected in load_graph's interface.
         self.options.cache_dir = os.devnull
         manager.saved_cache = {}
+        manager.only_load_from_cache = False
         # Active triggers during the last update
         self.triggered = []  # type: List[str]
 

mypy/test/testfinegrained.py

@@ -75,7 +75,8 @@ def run_case(self, testcase: DataDrivenTestCase) -> None:
             return
 
         main_src = '\n'.join(testcase.input)
-        sources_override = self.parse_sources(main_src)
+        step = 1
+        sources_override = self.parse_sources(main_src, step)
         messages, manager, graph = self.build(main_src, testcase, sources_override,
                                               build_cache=self.use_cache,
                                               enable_cache=self.use_cache)
@@ -92,6 +93,7 @@ def run_case(self, testcase: DataDrivenTestCase) -> None:
         steps = testcase.find_steps()
         all_triggered = []
         for operations in steps:
+            step += 1
             modules = []
             for op in operations:
                 if isinstance(op, UpdateFile):
@@ -102,6 +104,7 @@ def run_case(self, testcase: DataDrivenTestCase) -> None:
                     # Delete file
                     os.remove(op.path)
                     modules.append((op.module, op.path))
+            sources_override = self.parse_sources(main_src, step)
             if sources_override is not None:
                 modules = [(module, path)
                            for module, path in sources_override
@@ -181,14 +184,22 @@ def format_triggered(self, triggered: List[List[str]]) -> List[str]:
             result.append(('%d: %s' % (n + 2, ', '.join(filtered))).strip())
         return result
 
-    def parse_sources(self, program_text: str) -> Optional[List[Tuple[str, str]]]:
+    def parse_sources(self, program_text: str,
+                      incremental_step: int) -> Optional[List[Tuple[str, str]]]:
         """Return target (module, path) tuples for a test case, if not using the defaults.
 
         These are defined through a comment like '# cmd: main a.py' in the test case
         description.
         """
-        # TODO: Support defining separately for each incremental step.
         m = re.search('# cmd: mypy ([a-zA-Z0-9_./ ]+)$', program_text, flags=re.MULTILINE)
+        regex = '# cmd{}: mypy ([a-zA-Z0-9_./ ]+)$'.format(incremental_step)
+        alt_m = re.search(regex, program_text, flags=re.MULTILINE)
+        if alt_m is not None and incremental_step > 1:
+            # Optionally return a different command if in a later step
+            # of incremental mode, otherwise default to reusing the
+            # original cmd.
+            m = alt_m
+
         if m:
             # The test case wants to use a non-default set of files.
             paths = m.group(1).strip().split()

test-data/unit/fine-grained-modules.test

@@ -971,3 +971,121 @@ x = Foo()
 ==
 ==
 main:2: error: Too few arguments for "foo" of "Foo"
+
+-- This series of tests is designed to test adding a new module that
+-- doesn't appear in the cache, for cache mode. They aren't run only
+-- in cache mode, though, because they are still perfectly good
+-- regular tests.
+[case testAddModuleAfterCache1]
+# cmd: mypy main a.py
+# cmd2: mypy main a.py b.py
+# cmd3: mypy main a.py b.py
+import a
+[file a.py]
+pass
+[file a.py.2]
+import b
+b.foo(0)
+[file b.py.2]
+def foo() -> None: pass
+[file b.py.3]
+def foo(x: int) -> None: pass
+[out]
+==
+a.py:2: error: Too many arguments for "foo"
+==
+
+[case testAddModuleAfterCache2]
+# cmd: mypy main a.py
+# cmd2: mypy main a.py b.py
+# cmd3: mypy main a.py b.py
+# flags: --ignore-missing-imports --follow-imports=skip
+import a
+[file a.py]
+import b
+b.foo(0)
+[file b.py.2]
+def foo() -> None: pass
+[file b.py.3]
+def foo(x: int) -> None: pass
+[out]
+==
+a.py:2: error: Too many arguments for "foo"
+==
+
+[case testAddModuleAfterCache3]
+# cmd: mypy main a.py
+# cmd2: mypy main a.py b.py c.py d.py e.py f.py g.py
+# flags: --ignore-missing-imports --follow-imports=skip
+import a
+[file a.py]
+import b, c, d, e, f, g
+[file b.py.2]
+[file c.py.2]
+[file d.py.2]
+[file e.py.2]
+[file f.py.2]
+[file g.py.2]
+[out]
+==
+
+[case testAddModuleAfterCache4]
+# cmd: mypy main a.py
+# cmd2: mypy main a.py b.py
+# cmd3: mypy main a.py b.py
+# flags: --ignore-missing-imports --follow-imports=skip
+import a
+import b
+[file a.py]
+def foo() -> None: pass
+[file b.py.2]
+import a
+a.foo(10)
+[file a.py.3]
+def foo(x: int) -> None: pass
+[out]
+==
+b.py:2: error: Too many arguments for "foo"
+==
+
+[case testAddModuleAfterCache5]
+# cmd: mypy main a.py
+# cmd2: mypy main a.py b.py
+# cmd3: mypy main a.py b.py
+# flags: --ignore-missing-imports --follow-imports=skip
+import a
+import b
+[file a.py]
+def foo(x: int) -> None: pass
+[file a.py.2]
+def foo() -> None: pass
+[file b.py.2]
+import a
+a.foo(10)
+[file a.py.3]
+def foo(x: int) -> None: pass
+[out]
+==
+b.py:2: error: Too many arguments for "foo"
+==
+
+[case testAddModuleAfterCache6]
+# cmd: mypy main a.py
+# cmd2: mypy main a.py b.py
+# cmd3: mypy main a.py b.py
+# flags: --ignore-missing-imports --follow-imports=skip
+import a
+[file a.py]
+import b
+b.foo()
+[file a.py.2]
+import b
+b.foo(0)
+[file b.py.2]
+def foo() -> None: pass
+[file b.py.3]
+def foo(x: int) -> None: pass
+[out]
+==
+a.py:2: error: Too many arguments for "foo"
+==