Basic docstring support

Pretty similar to #78

src/Makefile

@@ -337,11 +337,15 @@ cpplint:
 
 .PHONY: check quick_check
 check:
+	@# These are ordered roughly in decreasing order of (chance will expose issue) / (time to run test)
 	$(MAKE) lint
 	$(MAKE) ext pyston_dbg
-	# $(MAKE) run_unittests
+
 	$(MAKE) check_dbg
-	$(MAKE) check_release
+
+	$(MAKE) check_format
+	$(MAKE) run_unittests
+
 	@# jit_prof forces the use of GCC as the compiler, which can expose other errors, so just build it and see what happens:
 	# $(MAKE) check_prof
 	$(MAKE) pyston_prof
@@ -349,9 +353,7 @@ check:
 	$(call checksha,./pyston_prof -cqn $(TESTS_DIR)/raytrace_small.py,0544f4621dd45fe94205219488a2576b84dc044d)
 	$(call checksha,./pyston_prof -cqO $(TESTS_DIR)/raytrace_small.py,0544f4621dd45fe94205219488a2576b84dc044d)
 
-	$(MAKE) run_unittests
-	$(MAKE) check_format
-
+	$(MAKE) check_release
 	echo "All tests passed"
 
 quick_check:

src/codegen/irgen/irgenerator.cpp

@@ -1404,10 +1404,29 @@ private:
         // cls->setattr(emitter, "__name__", name);
         // name->decvref(emitter);
 
+        bool had_docstring = false;
+        static std::string doc_str("__doc__");
+
         for (int i = 0, n = node->body.size(); i < n; i++) {
             AST_TYPE::AST_TYPE type = node->body[i]->type;
             if (type == AST_TYPE::Pass) {
                 continue;
+            } else if (type == AST_TYPE::Expr) {
+                AST_Expr* expr = ast_cast<AST_Expr>(node->body[i]);
+
+                if (expr->value->type == AST_TYPE::Str) {
+                    if (i == 0) {
+                        had_docstring = true;
+                        CompilerVariable* str = evalExpr(expr->value, exc_info);
+                        cls->setattr(emitter, getEmptyOpInfo(exc_info), &doc_str, str);
+                    }
+                } else {
+                    fprintf(stderr, "Currently don't support non-noop expressions in classes:\n");
+                    printf("On line %d: ", expr->lineno);
+                    print_ast(expr);
+                    printf("\n");
+                    abort();
+                }
             } else if (type == AST_TYPE::FunctionDef) {
                 AST_FunctionDef* fdef = ast_cast<AST_FunctionDef>(node->body[i]);
                 assert(fdef->args->defaults.size() == 0);
@@ -1424,6 +1443,10 @@ private:
             }
         }
 
+        if (!had_docstring) {
+            cls->setattr(emitter, getEmptyOpInfo(exc_info), &doc_str, getNone());
+        }
+
         _doSet(node->name, cls, exc_info);
         cls->decvref(emitter);
     }

src/runtime/objmodel.cpp

@@ -2944,7 +2944,7 @@ extern "C" Box* import(const std::string* name) {
             continue;
 
         if (VERBOSITY() >= 1)
-            printf("Beginning import of %s...\n", fn.c_str());
+            printf("Importing %s from %s\n", name->c_str(), fn.c_str());
 
         // TODO duplication with jit.cpp:
         BoxedModule* module = createModule(*name, fn);

test/tests/docstrings.py

+class C1(object):
+    "hello world"
+print C1.__doc__
+
+class C2(object):
+    "doc1"
+    "doc2"
+print C2.__doc__
+
+class C3(object):
+    pass
+print C3.__doc__
+
+"""
+# Not supported yet:
+
+class C3(object):
+    1
+assert C3.__doc__ is None
+
+class C4(object):
+    ("a")
+assert C3.__doc__ is None
+"""