From 375e9f050de6b09c00eecafd63bd9b967fbeb335 Mon Sep 17 00:00:00 2001
From: lemon <lsof@mailbox.org>
Date: Wed, 26 Nov 2025 18:46:44 +0100
Subject: c/type: make implicit const T* -> T* conversion warning, not error

---
 c/c.c  | 9 ++++++++-
 io.c   | 3 ++-
 type.c | 3 +--
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/c/c.c b/c/c.c
index 5dd4368..c50ffa7 100644
--- a/c/c.c
+++ b/c/c.c
@@ -342,7 +342,14 @@ argpromote(union type t)
 bool
 assigncheck(union type t, const struct expr *src)
 {
-   if (assigncompat(t, typedecay(src->ty))) return 1;
+   union type srcty = typedecay(src->ty);;
+   if (assigncompat(t, srcty)) {
+      if (t.t == TYPTR && srcty.t == TYPTR
+       && (t.flag & TFCHLDQUAL & srcty.flag & TFCHLDQUAL) != (srcty.flag & TFCHLDQUAL)) {
+         warn(&src->span, "usage of '%ty' discards pointer qualifiers", src->ty);
+      }
+      return 1;
+   }
    if (t.t == TYPTR && iszero(*src)) return 1;
    return 0;
 }
diff --git a/io.c b/io.c
index b3119fc..58ebf17 100644
--- a/io.c
+++ b/io.c
@@ -1011,10 +1011,11 @@ vdiag(const struct span *span, enum diagkind kind, const char *fmt, va_list ap)
          do {
             ioputc(&bstderr, mark);
             mark = '~';
-         } while (--nmark && ++j < end);
+         } while (--nmark > 0 && ++j < end);
          col = 1;
          ++line;
          efmt("%g.\n");
+         --nmark;
       }
       ioputc(&bstderr,  '\n');
    }
diff --git a/type.c b/type.c
index 78a6278..5025395 100644
--- a/type.c
+++ b/type.c
@@ -257,8 +257,7 @@ assigncompat(union type dst, union type src)
    if (dst.t == TYPTR && src.t == TYPTR) {
       ds = typechild(dst);
       ss = typechild(src);
-      if (ds.bits == ss.bits || ss.t == TYVOID || ds.t == TYVOID)
-         return ((dst.flag & TFCHLDQUAL) & (src.flag & TFCHLDQUAL)) == (src.flag & TFCHLDQUAL);
+      return ds.bits == ss.bits || ss.t == TYVOID || ds.t == TYVOID;
    }
    if (dst.t == TYBOOL && src.t == TYPTR)
       return 1;
-- 
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