Attach __doc__ to modules, default to None (but still set) if missing

compiler.c

@@ -2012,6 +2012,20 @@ KrkFunction * krk_compile(const char * src, int newScope, char * fileName) {
 
 	advance();
 
+	if (vm.module) {
+		KrkValue doc;
+		if (!krk_tableGet(&vm.module->fields, OBJECT_VAL(krk_copyString("__doc__", 7)), &doc)) {
+			if (match(TOKEN_STRING) || match(TOKEN_BIG_STRING)) {
+				string(parser.previous.type == TOKEN_BIG_STRING);
+				krk_attachNamedObject(&vm.module->fields, "__doc__",
+					(KrkObj*)AS_STRING(currentChunk()->constants.values[currentChunk()->constants.count-1]));
+				consume(TOKEN_EOL,"Garbage after docstring");
+			} else {
+				krk_attachNamedValue(&vm.module->fields, "__doc__", NONE_VAL());
+			}
+		}
+	}
+
 	while (!match(TOKEN_EOF)) {
 		declaration();
 		if (check(TOKEN_EOL) || check(TOKEN_INDENTATION) || check(TOKEN_EOF)) {

kuroko.c

@@ -68,6 +68,7 @@ int main(int argc, char * argv[]) {
 		krk_defineNative(&vm.builtins->fields, "exit", exitFunc);
 		krk_defineNative(&vm.builtins->fields, "paste", paste);
 		krk_startModule("<module>");
+		krk_attachNamedValue(&vm.module->fields,"__doc__", NONE_VAL());
 
 		/* Set ^D to send EOF */
 		rline_exit_string="";

test/testModuleDocstring.krk

@@ -0,0 +1,4 @@
+#!/usr/bin/kuroko
+"""This is a docstring."""
+
+print("hello, here is my docstring:",__doc__)

test/testModuleDocstring.krk.expect

@@ -0,0 +1 @@
+hello, here is my docstring: This is a docstring.

vm.c

@@ -3449,14 +3449,14 @@ _finishException:
 
 KrkInstance * krk_startModule(const char * name) {
 	KrkInstance * module = krk_newInstance(vm.objectClass);
-	vm.module = (KrkObj*)module;
+	vm.module = module;
 	krk_attachNamedObject(&module->fields, "__builtins__", (KrkObj*)vm.builtins);
 	krk_attachNamedObject(&module->fields, "__name__", (KrkObj*)krk_copyString(name,strlen(name)));
 	return module;
 }
 
 KrkValue krk_interpret(const char * src, int newScope, char * fromName, char * fromFile) {
-	KrkObj * enclosing = vm.module;
+	KrkInstance * enclosing = vm.module;
 	if (newScope) krk_startModule(fromName);
 
 	KrkFunction * function = krk_compile(src, 0, fromFile);

vm.h

@@ -49,7 +49,7 @@ typedef struct {
 	size_t stackSize;
 	KrkValue * stack;
 	KrkValue * stackTop;
-	KrkObj   * module;
+	KrkInstance * module;
 	KrkTable strings;
 	KrkTable modules;
 	KrkUpvalue * openUpvalues;