From 1645327551e7058659cd767269aea6053546c95d Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 15 Apr 2026 14:59:52 +0300
Subject: [PATCH] cgen: fix local headers not found (fixes #14706)

---
 vlib/v/gen/c/cgen.v                           | 25 ++++++++++++++++++-
 .../project_with_c_code_2/modc/wrapper.c.v    |  1 -
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 0727e3f3e..dc73383c9 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -8260,10 +8260,33 @@ fn matching_generated_shader_source(node ast.HashStmt) ?string {
 	return shader_source
 }
 
+fn resolved_existing_local_include_path(node ast.HashStmt) ?string {
+	if !node.main.starts_with('"') || !node.main.ends_with('"') {
+		return none
+	}
+	header_path := node.main.trim('"')
+	if os.is_abs_path(header_path) {
+		return none
+	}
+	resolved_header_path := os.join_path(os.dir(node.source_file), header_path)
+	if !os.is_file(resolved_header_path) {
+		return none
+	}
+	return os.real_path(resolved_header_path).replace('\\', '/')
+}
+
+fn include_path_for_generated_c(node ast.HashStmt) string {
+	if resolved_header_path := resolved_existing_local_include_path(node) {
+		return '"${resolved_header_path}"'
+	}
+	return node.main
+}
+
 fn (mut g Gen) hash_stmt_guarded_include(node ast.HashStmt) string {
 	mut missing_message := 'Header file ${node.main}, needed for module `${node.mod}` was not found.'
 	missing_message += ' ${missing_shader_header_message(node)}'
-	mut guarded_include := get_guarded_include_text(node.main, missing_message)
+	mut guarded_include := get_guarded_include_text(include_path_for_generated_c(node),
+		missing_message)
 	if node.main == '<errno.h>' {
 		// fails with musl-gcc and msvc; but an unguarded include works:
 		guarded_include = '#include ${node.main}'
diff --git a/vlib/v/tests/project_with_c_code_2/modc/wrapper.c.v b/vlib/v/tests/project_with_c_code_2/modc/wrapper.c.v
index 465d4cb45..903a03136 100644
--- a/vlib/v/tests/project_with_c_code_2/modc/wrapper.c.v
+++ b/vlib/v/tests/project_with_c_code_2/modc/wrapper.c.v
@@ -1,6 +1,5 @@
 module modc
 
-#flag -I @VMODROOT/modc
 #flag @VMODROOT/modc/impl.o
 #include "header.h"
 
-- 
2.39.5