From 1ee69b6b1383f03fb8e060196ed781c171561d45 Mon Sep 17 00:00:00 2001
From: nsfisis <nsfisis@gmail.com>
Date: Sat, 10 Jan 2026 11:51:19 +0900
Subject: feat: support (void) cast

---
 justfile                  |  3 +++
 src/codegen.c             |  4 ++++
 tests/cast_expressions.sh | 17 +++++++++++++++++
 3 files changed, 24 insertions(+)

diff --git a/justfile b/justfile
index 06c46db..2873de3 100644
--- a/justfile
+++ b/justfile
@@ -36,3 +36,6 @@ test-all:
 clean:
     rm -rf build
     rm -rf tests/tmp
+
+fmt:
+    nix fmt
diff --git a/src/codegen.c b/src/codegen.c
index be8acd7..e0e0b19 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -148,6 +148,10 @@ static void codegen_deref_expr(CodeGen* g, AstNode* ast, GenMode gen_mode) {
 static void codegen_cast_expr(CodeGen* g, AstNode* ast) {
     codegen_expr(g, ast->node_operand, GenMode_rval);
 
+    // (void) cast does nothing.
+    if (ast->ty->kind == TypeKind_void)
+        return;
+
     int src_size = type_sizeof(ast->node_operand->ty);
     int dst_size = type_sizeof(ast->ty);
 
diff --git a/tests/cast_expressions.sh b/tests/cast_expressions.sh
index f6824ad..b493e04 100644
--- a/tests/cast_expressions.sh
+++ b/tests/cast_expressions.sh
@@ -152,3 +152,20 @@ int main() {
     return 0;
 }
 EOF
+
+cat <<'EOF' > expected
+42
+EOF
+test_diff <<'EOF'
+int printf(const char*, ...);
+
+int f() {
+    return printf("42\n");
+}
+
+int main() {
+    (void)123;
+    (void)(5 + 6 + 7);
+    (void)f();
+}
+EOF
-- 
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