Remove the module from sys.modules if importing failed

from_cpython/Lib/modulefinder.py

@@ -3,11 +3,6 @@
 
 from __future__ import generators
 
-# Pyston change:
-import sys
-del sys.modules['modulefinder']
-raise ImportError("This isn't really supported in Pyston yet")
-
 import dis
 import imp
 import marshal

src/runtime/import.cpp

@@ -32,11 +32,22 @@ static const std::string path_str("__path__");
 static const std::string package_str("__package__");
 static BoxedClass* null_importer_cls;
 
+static void removeModule(const std::string& name) {
+    BoxedDict* d = getSysModulesDict();
+    Box* b_name = boxString(name);
+    d->d.erase(b_name);
+}
+
 BoxedModule* createAndRunModule(const std::string& name, const std::string& fn) {
     BoxedModule* module = createModule(name, fn);
 
     AST_Module* ast = caching_parse_file(fn.c_str());
+    try {
         compileAndRunModule(ast, module);
+    } catch (ExcInfo e) {
+        removeModule(name);
+        raiseRaw(e);
+    }
     return module;
 }
 
@@ -51,7 +62,12 @@ static BoxedModule* createAndRunModule(const std::string& name, const std::strin
     module->setattr(path_str, path_list, NULL);
 
     AST_Module* ast = caching_parse_file(fn.c_str());
+    try {
         compileAndRunModule(ast, module);
+    } catch (ExcInfo e) {
+        removeModule(name);
+        raiseRaw(e);
+    }
     return module;
 }
 
@@ -363,6 +379,7 @@ static Box* importSub(const std::string& name, const std::string& full_name, Box
     if (sr.type != SearchResult::SEARCH_ERROR) {
         Box* module;
 
+        try {
             if (sr.type == SearchResult::PY_SOURCE)
                 module = createAndRunModule(full_name, sr.path);
             else if (sr.type == SearchResult::PKG_DIRECTORY)
@@ -376,6 +393,10 @@ static Box* importSub(const std::string& name, const std::string& full_name, Box
                                   boxString(full_name), NULL, NULL, NULL, NULL);
             } else
                 RELEASE_ASSERT(0, "%d", sr.type);
+        } catch (ExcInfo e) {
+            removeModule(name);
+            raiseRaw(e);
+        }
 
         if (parent_module && parent_module != None)
             parent_module->setattr(name, module, NULL);
@@ -609,6 +630,7 @@ extern "C" PyObject* PyImport_ExecCodeModuleEx(char* name, PyObject* co, char* p
         module->setattr("__file__", boxString(pathname), NULL);
         return module;
     } catch (ExcInfo e) {
+        removeModule(name);
         setCAPIException(e);
         return NULL;
     }

test/tests/import_failure_target.py

+# skip-if: True
+
+import sys
+print "import_failure_target" in sys.modules
+raise Exception("pretending submodule didn't import")

test/tests/import_failure_test.py

@@ -62,3 +62,15 @@ def f2():
     except NameError, e:
         print e
 f2()
+
+try:
+    import import_failure_target
+    raise Exception("This should not be importable")
+except Exception, e:
+    print type(e), e
+
+try:
+    import import_failure_target
+    raise Exception("This should not be importable if we tried it again")
+except Exception, e:
+    print type(e), e