From 519522449252389f265dc8db40d833a0a5770b5d Mon Sep 17 00:00:00 2001
From: lemon <lsof@mailbox.org>
Date: Sun, 14 Sep 2025 10:12:43 +0200
Subject: frontend: warn k&r function declaration

---
 c.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/c.c b/c.c
index d4fb280..d059cda 100644
--- a/c.c
+++ b/c.c
@@ -2117,6 +2117,8 @@ declarator(struct declstate *st, struct comp *cm) {
             error(&decl.span, "function cannot return array type", decl.ty);
          else if (decl.ty.t != TYVOID && isincomplete(decl.ty))
             error(&decl.span, "function cannot return incomplete type (%ty)", decl.ty);
+         if (l->kandr && ccopt.cstd > STDC89)
+            warn(&l->span, "function declaration without a prototype is deprecated");
          decl.ty = mkfntype(decl.ty, l->npar, l->param, l->pqual, l->kandr, l->variadic);
          if (l->param != declparamtmp) free(l->param);
          if (l->pqual != declpqualtmp) free(l->pqual);
-- 
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