From e38ecde989fe378c49a61d6975784ccfb703cfee Mon Sep 17 00:00:00 2001
From: Bruce Hill <bruce@bruce-hill.com>
Date: Sat, 30 Nov 2024 14:59:28 -0500
Subject: Explicitly forbid nested optional types

---
 compile.c   |  3 +++
 parse.c     | 14 ++++++--------
 typecheck.c |  4 ++++
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/compile.c b/compile.c
index bc035343..674bded3 100644
--- a/compile.c
+++ b/compile.c
@@ -2520,6 +2520,9 @@ CORD compile(env_t *env, ast_t *ast)
         type_t *key_t = Match(table_type, TableType)->key_type;
         type_t *value_t = Match(table_type, TableType)->value_type;
 
+        if (value_t->tag == OptionalType)
+            code_err(ast, "Tables whose values are optional (%T) are not currently supported.", value_t);
+
         for (ast_list_t *entry = table->entries; entry; entry = entry->next) {
             if (entry->ast->tag == Comprehension)
                 goto table_comprehension;
diff --git a/parse.c b/parse.c
index eb77c181..37956055 100644
--- a/parse.c
+++ b/parse.c
@@ -632,10 +632,9 @@ type_ast_t *parse_pointer_type(parse_ctx_t *ctx, const char *pos) {
                               "I couldn't parse a pointer type after this point");
     type_ast_t *ptr_type = NewTypeAST(ctx->file, start, pos, PointerTypeAST, .pointed=type, .is_view=is_view);
     spaces(&pos);
-    if (match(&pos, "?"))
-        return NewTypeAST(ctx->file, start, pos, OptionalTypeAST, .type=ptr_type);
-    else
-        return ptr_type;
+    while (match(&pos, "?"))
+        ptr_type = NewTypeAST(ctx->file, start, pos, OptionalTypeAST, .type=ptr_type);
+    return ptr_type;
 }
 
 type_ast_t *parse_type_name(parse_ctx_t *ctx, const char *pos) {
@@ -685,10 +684,9 @@ type_ast_t *parse_type(parse_ctx_t *ctx, const char *pos) {
     if (!type) return NULL;
     pos = type->end;
     spaces(&pos);
-    if (match(&pos, "?"))
-        return NewTypeAST(ctx->file, start, pos, OptionalTypeAST, .type=type);
-    else
-        return type;
+    while (match(&pos, "?"))
+        type = NewTypeAST(ctx->file, start, pos, OptionalTypeAST, .type=type);
+    return type;
 }
 
 PARSER(parse_num) {
diff --git a/typecheck.c b/typecheck.c
index e602c774..82c1f84a 100644
--- a/typecheck.c
+++ b/typecheck.c
@@ -93,6 +93,8 @@ type_t *parse_type_ast(env_t *env, type_ast_t *ast)
         if (!val_type) code_err(val_type_ast, "I can't figure out what type this is.");
         if (has_view_memory(val_type))
             code_err(val_type_ast, "Tables can't have stack references because the array may outlive the stack frame.");
+        else if (val_type->tag == OptionalType)
+            code_err(ast, "Tables with optional-typed values are not currently supported");
         return Type(TableType, .key_type=key_type, .value_type=val_type);
     }
     case FunctionTypeAST: {
@@ -118,6 +120,8 @@ type_t *parse_type_ast(env_t *env, type_ast_t *ast)
         type_t *t = parse_type_ast(env, opt->type);
         if (t->tag == VoidType || t->tag == AbortType || t->tag == ReturnType)
             code_err(ast, "Optional %T types are not supported.", t);
+        else if (t->tag == OptionalType)
+            code_err(ast, "Nested optional types are not currently supported");
         return Type(OptionalType, .type=t);
     }
     case UnknownTypeAST: code_err(ast, "I don't know how to get this type");
-- 
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