From c1c9fa8250306ec7612d62521f2943e3a029d11d Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 11 Mar 2026 14:12:29 +0300
Subject: [PATCH] cgen: types are not respected with -no-builtin (fixes #21264)

---
 vlib/v/gen/c/cgen.v                           | 17 ++++++++++++-
 .../gen/c/no_builtin_no_preludes_types_test.v | 19 ++++++++++++++
 .../testdata/no_builtin_no_preludes_types.vv  | 25 +++++++++++++++++++
 3 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/gen/c/no_builtin_no_preludes_types_test.v
 create mode 100644 vlib/v/gen/c/testdata/no_builtin_no_preludes_types.vv

diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 985152383..e4ea6cc45 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -1829,6 +1829,20 @@ static inline ${option_name}_void __Option_${styp}_pushval(${styp} ch, ${el_type
 // cc_type whether to prefix 'struct' or not (C__Foo -> struct Foo)
 fn (mut g Gen) cc_type(typ ast.Type, is_prefix_struct bool) string {
 	sym := g.table.sym(g.unwrap_generic(typ))
+	if g.pref.no_preludes {
+		match sym.kind {
+			.voidptr {
+				return 'void*'
+			}
+			.charptr {
+				return 'char*'
+			}
+			.byteptr {
+				return 'unsigned char*'
+			}
+			else {}
+		}
+	}
 	mut styp := sym.scoped_cname()
 	// TODO: this needs to be removed; cgen shouldn't resolve generic types (job of checker)
 	match sym.info {
@@ -1878,7 +1892,8 @@ pub fn (mut g Gen) write_typedef_types() {
 			.array {
 				info := sym.info as ast.Array
 				elem_sym := g.table.sym(info.elem_type)
-				if elem_sym.kind != .placeholder && !info.elem_type.has_flag(.generic) {
+				if !g.pref.no_preludes && elem_sym.kind != .placeholder
+					&& !info.elem_type.has_flag(.generic) {
 					g.type_definitions.writeln('typedef array ${sym.cname};')
 				}
 			}
diff --git a/vlib/v/gen/c/no_builtin_no_preludes_types_test.v b/vlib/v/gen/c/no_builtin_no_preludes_types_test.v
new file mode 100644
index 000000000..03cbe4a35
--- /dev/null
+++ b/vlib/v/gen/c/no_builtin_no_preludes_types_test.v
@@ -0,0 +1,19 @@
+import os
+
+const vexe = @VEXE
+
+const vroot = os.real_path(@VMODROOT)
+
+const testdata_file = os.join_path(vroot, 'vlib/v/gen/c/testdata/no_builtin_no_preludes_types.vv')
+
+fn test_no_builtin_no_preludes_types_are_lowered_to_c() {
+	os.chdir(vroot) or {}
+	cmd := '${os.quoted_path(vexe)} -no-builtin -no-preludes -enable-globals -gc none -no-skip-unused -o - ${os.quoted_path(testdata_file)}'
+	compilation := os.execute(cmd)
+	assert compilation.exit_code == 0
+	generated_c := compilation.output.replace('\r\n', '\n')
+	assert !generated_c.contains('typedef array Array_charptr;')
+	assert !generated_c.contains('voidptr file')
+	assert generated_c.contains('main__proc_read(void* file, char* buff, u32 size, u64* offset);')
+	assert generated_c.contains('(void*,char*,u32,u64*);')
+}
diff --git a/vlib/v/gen/c/testdata/no_builtin_no_preludes_types.vv b/vlib/v/gen/c/testdata/no_builtin_no_preludes_types.vv
new file mode 100644
index 000000000..d9e2563f2
--- /dev/null
+++ b/vlib/v/gen/c/testdata/no_builtin_no_preludes_types.vv
@@ -0,0 +1,25 @@
+// vtest vflags: -no-builtin -no-preludes -enable-globals -gc none
+module main
+
+fn C.klog(...charptr)
+fn C.proc_create(charptr, int, int, &C.proc_ops)
+
+struct C.proc_ops {
+	proc_read fn (voidptr, &char, u32, &u64)
+}
+
+fn proc_read(file voidptr, buff &char, size u32, offset &u64) {}
+
+__global fops = C.proc_ops{
+	proc_read: proc_read
+}
+
+fn custom_init() int {
+	C.klog(c'Hello module %s!\n', c'proc')
+	C.proc_create(c'proc_proc', 0, 0, &fops)
+	return 0
+}
+
+fn main() {
+	custom_init()
+}
-- 
2.39.5