fix scoping big

5 files changed, 67 insertions, 20 deletions

diff --git a/ast.h b/ast.h
index 918ae68..6ff95df 100644
--- a/ast.h
+++ b/ast.h
@@ -136,6 +136,7 @@ struct if_node {
     struct expr_node* cond;
     struct stmt_node* true_branch;
     struct stmt_node* false_branch;
+    struct scope* scope;
 };
 
 struct stmt_node {
diff --git a/codegen.c b/codegen.c
index f126bda..79deb46 100644
--- a/codegen.c
+++ b/codegen.c
@@ -36,6 +36,21 @@ static struct scope* scope;
 static const struct fn_decl_node* active_fn;
 static unsigned long long branch_counter = 0;
 
+static void enter_scope(struct scope* child_scope) {
+    if (child_scope == NULL ||
+            child_scope->next_out != scope)
+        CGEN_PANIC("enter_scope: scopes are misaligned");
+
+    scope = child_scope;
+}
+
+static void exit_scope(struct scope* child_scope) {
+    if (child_scope != scope || child_scope->next_out == NULL)
+        CGEN_PANIC("exit_scope: scopes are misaligned");
+
+    scope = child_scope->next_out;
+}
+
 static struct lval_def allocate_register(const struct type_def* type) {
     return (struct lval_def) {
         .loc = {
@@ -547,20 +562,19 @@ static void emit_group_contents(FILE* outfile, const struct group_node* node) {
 }
 
 static void emit_group(FILE* outfile, const struct group_node* node) {
-    if (node->scope->next_out != scope) CGEN_PANIC("scopes are misaligned");
-
-    scope = node->scope;
+    enter_scope(node->scope);
     scope->bp_offset = scope->next_out->bp_offset; /* don't reset bp */
 
     emit_group_contents(outfile, node);
 
     /* don't reset sp because alloca needs to work */
     scope->next_out->bp_offset = scope->bp_offset;
-    scope = scope->next_out;
+    exit_scope(node->scope);
 }
 
 static void emit_if(FILE* outfile, const struct if_node* node) {
-    /* TODO: make type checking real so we aren't passing a null pointer here */
+    enter_scope(node->scope);
+
     struct lval_def cond_result =
         allocate_temporary(outfile, node->cond->resolved_type);
     emit_expr(outfile, node->cond, &cond_result);
@@ -579,6 +593,8 @@ static void emit_if(FILE* outfile, const struct if_node* node) {
         emit_stmt(outfile, node->false_branch);
         fprintf(outfile, "branch%lld:\n", end_branch_num);
     }
+
+    exit_scope(node->scope);
 }
 
 static void emit_stmt(FILE* outfile, const struct stmt_node* node) {
@@ -604,6 +620,8 @@ static void emit_stmt(FILE* outfile, const struct stmt_node* node) {
 }
 
 static void emit_fn_decl(FILE* outfile, const struct fn_decl_node* node) {
+    enter_scope(node->scope);
+
     if (active_fn != NULL)
         CGEN_PANIC(
             "can't define function %s inside function %s",
@@ -615,8 +633,6 @@ static void emit_fn_decl(FILE* outfile, const struct fn_decl_node* node) {
     fprintf(outfile, "\tpush rbp\n");
     fprintf(outfile, "\tmov rbp, rsp\n");
 
-    if (node->scope->next_out != scope) CGEN_PANIC("scopes are misaligned");
-    scope = node->scope;
     scope->bp_offset = 0;
 
     long long spilled_bp_ofs = -16; // return address + old bp
@@ -644,15 +660,17 @@ static void emit_fn_decl(FILE* outfile, const struct fn_decl_node* node) {
         emit_mov(outfile, &arg_dst, &arg_src);
     }
 
+    enter_scope(node->body.scope);
     emit_group_contents(outfile, &node->body);
-
-    scope = scope->next_out;
+    exit_scope(node->body.scope);
 
     fprintf(outfile, RETURN_LABEL_FMT ":\n", node->name);
     fprintf(outfile, "\tmov rsp, rbp\n");
     fprintf(outfile, "\tpop rbp\n");
     fprintf(outfile, "\tret\n");
+
     active_fn = NULL;
+    exit_scope(node->scope);
 }
 
 static void emit_root_node(FILE* outfile, const struct root_node* node) {
diff --git a/parser.c b/parser.c
index 40cdb1c..4779e73 100644
--- a/parser.c
+++ b/parser.c
@@ -324,6 +324,9 @@ static void parse_group(struct group_node* p_node) {
 static void parse_if(struct if_node* p_node) {
     expect_kw("if");
 
+    scope_push(&scope);
+    p_node->scope = scope;
+
     expect(TK_LPAREN);
     p_node->cond = protected_alloc(sizeof(struct expr_node));
     parse_expr(p_node->cond);
@@ -333,11 +336,14 @@ static void parse_if(struct if_node* p_node) {
     parse_stmt(p_node->true_branch);
 
     peek_or_panic();
-    if (tok.type != TK_IDENT || strcmp(tok.data.ident, "else") != 0) return;
-    expect_kw("else");
+    if (tok.type == TK_IDENT && strcmp(tok.data.ident, "else") == 0) {
+        expect_kw("else");
 
-    p_node->false_branch = protected_alloc(sizeof(struct stmt_node));
-    parse_stmt(p_node->false_branch);
+        p_node->false_branch = protected_alloc(sizeof(struct stmt_node));
+        parse_stmt(p_node->false_branch);
+    }
+
+    scope_pop(&scope);
 }
 
 static void parse_stmt_assign(struct stmt_node* p_node) {
@@ -419,6 +425,9 @@ static void parse_args_decl(struct args_decl_node** pp_decl) {
 }
 
 static void parse_fn_decl(struct fn_decl_node* p_node) {
+    if (scope->next_out != NULL)
+        PARSER_PANIC("functions can only be define in the root scope");
+
     parse_type_ref(&p_node->return_type);
 
     expect(TK_IDENT);
diff --git a/test/fibonacci.c b/test/fibonacci.c
index 39a32be..a07c111 100644
--- a/test/fibonacci.c
+++ b/test/fibonacci.c
@@ -1,6 +1,6 @@
 int fib (int n) {
     if (n) return n * fib(n-1);
-    return 1;
+    else return 1;
 }
 
 int main (int argc, char** argv) {
diff --git a/type_checker.c b/type_checker.c
index 2842ea2..aabd7c9 100644
--- a/type_checker.c
+++ b/type_checker.c
@@ -33,6 +33,21 @@ static void assert_cast_compatible(
     }
 }
 
+static void enter_scope(struct scope* child_scope) {
+    if (child_scope == NULL ||
+            child_scope->next_out != scope)
+        TYPE_PANIC("enter_scope: scopes are misaligned");
+
+    scope = child_scope;
+}
+
+static void exit_scope(struct scope* child_scope) {
+    if (child_scope != scope || child_scope->next_out == NULL)
+        TYPE_PANIC("exit_scope: scopes are misaligned");
+
+    scope = child_scope->next_out;
+}
+
 static const struct type_def* resolve_type_ref(struct type_ref_node* node) {
     /* TODO: support pointers and such */
     if (node->def_ref == NULL) TYPE_PANIC("use of unresolved type");
@@ -160,9 +175,13 @@ static void type_check_return(struct return_node* node) {
 }
 
 static void type_check_if(struct if_node* node) {
+    enter_scope(node->scope);
+
     type_check_expr(node->cond);
     type_check_stmt(node->true_branch);
     if (node->false_branch != NULL) type_check_stmt(node->false_branch);
+
+    exit_scope(node->scope);
 }
 
 static void type_check_stmt(struct stmt_node* node) {
@@ -188,19 +207,19 @@ static void type_check_stmt(struct stmt_node* node) {
 }
 
 static void type_check_group(struct group_node* node) {
-    if (node->scope->next_out != scope) TYPE_PANIC("scopes are borked");
-    scope = node->scope;
+    enter_scope(node->scope);
+
     struct stmt_node* stmt = node->head;
     while (stmt != NULL) {
         type_check_stmt(stmt);
         stmt = stmt->next;
     }
-    scope = scope->next_out;
+
+    exit_scope(node->scope);
 }
 
 static void type_check_fn_decl(struct fn_decl_node* node) {
-    if (node->scope->next_out != scope) TYPE_PANIC("scopes are borked");
-    scope = node->scope;
+    enter_scope(node->scope);
 
     node->return_type.def_ref = resolve_type_ref(&node->return_type);
 
@@ -211,7 +230,7 @@ static void type_check_fn_decl(struct fn_decl_node* node) {
 
     type_check_group(&node->body);
 
-    scope = scope->next_out;
+    exit_scope(node->scope);
 }
 
 static void type_check_root(struct root_node* node) {