From 16aa2c081db71181ba33aa205d2b0699efa29a99 Mon Sep 17 00:00:00 2001
From: nsfisis <nsfisis@gmail.com>
Date: Tue, 2 Sep 2025 00:17:51 +0900
Subject: feat: support constant expression in array size

---
 src/parse.c  |  9 ++++-----
 tests/118.sh | 19 +++++++++++++++++++
 2 files changed, 23 insertions(+), 5 deletions(-)
 create mode 100644 tests/118.sh

diff --git a/src/parse.c b/src/parse.c
index 57dd316..ecd8e65 100644
--- a/src/parse.c
+++ b/src/parse.c
@@ -870,6 +870,8 @@ static Type* parse_pointer_opt(Parser* p, Type* ty) {
     return ty;
 }
 
+static int eval(AstNode* e);
+
 // array-declarator:
 //     direct-declarator '[' TODO type-qualifier-list? TODO assignment-expression? ']'
 //     TODO direct-declarator '[' 'static' type-qualifier-list? assignment-expression? ']'
@@ -878,11 +880,8 @@ static Type* parse_pointer_opt(Parser* p, Type* ty) {
 static Type* parse_array_declarator_suffix(Parser* p, Type* ty) {
     next_token(p); // skip '['
 
-    AstNode* size_expr = parse_expr(p);
-    if (size_expr->kind != AstNodeKind_int_expr) {
-        fatal_error("parse_var_decl: invalid array size");
-    }
-    int size = size_expr->node_int_value;
+    AstNode* size_expr = parse_assignment_expr(p);
+    int size = eval(size_expr);
     expect(p, TokenKind_bracket_r);
 
     return type_new_array(ty, size);
diff --git a/tests/118.sh b/tests/118.sh
new file mode 100644
index 0000000..48a8569
--- /dev/null
+++ b/tests/118.sh
@@ -0,0 +1,19 @@
+cat <<'EOF' > expected
+400
+80
+16
+EOF
+
+test_diff <<'EOF'
+int printf();
+
+int main() {
+    int a[10 * 10];
+    int b[10 + 10];
+    int c[1 << 2];
+
+    printf("%zu\n", sizeof(a));
+    printf("%zu\n", sizeof(b));
+    printf("%zu\n", sizeof(c));
+}
+EOF
-- 
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