From 02fa15644899c2a3feae1f161730c19666e5846e Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Thu, 23 Apr 2026 19:30:29 +0300
Subject: [PATCH] tools: fix v doc: cannot generate an HTML documentation of my
 own project (fixes #9170)

---
 .../get_parent_mod_issue_14224_test.v         | 30 +++++++
 cmd/tools/vdoc/document/module.v              | 84 ++++++++++++++++---
 2 files changed, 101 insertions(+), 13 deletions(-)

diff --git a/cmd/tools/vdoc/document/get_parent_mod_issue_14224_test.v b/cmd/tools/vdoc/document/get_parent_mod_issue_14224_test.v
index a73736247..f20aa8fe3 100644
--- a/cmd/tools/vdoc/document/get_parent_mod_issue_14224_test.v
+++ b/cmd/tools/vdoc/document/get_parent_mod_issue_14224_test.v
@@ -15,3 +15,33 @@ fn test_get_parent_mod_stops_at_current_vmod_issue_14224() {
 	os.write_file(os.join_path(project_dir, 'project.v'), 'module project')!
 	assert get_parent_mod(project_dir)! == ''
 }
+
+fn test_lookup_module_with_path_finds_current_project_root_issue_9170() {
+	tmp_dir := os.join_path(os.vtmp_dir(), 'vdoc_lookup_module_issue_9170_${os.getpid()}')
+	os.rmdir_all(tmp_dir) or {}
+	defer {
+		os.rmdir_all(tmp_dir) or {}
+	}
+	project_dir := os.join_path(tmp_dir, 'issue9170')
+	os.mkdir_all(project_dir)!
+	os.write_file(os.join_path(project_dir, 'v.mod'), "Module {\n\tname: 'issue9170'\n}\n")!
+	os.write_file(os.join_path(project_dir, 'main.v'), 'module main\n')!
+	assert lookup_module_with_path('issue9170', project_dir)! == os.real_path(project_dir)
+}
+
+fn test_lookup_module_with_path_uses_vmod_source_root_issue_9170() {
+	tmp_dir := os.join_path(os.vtmp_dir(),
+		'vdoc_lookup_module_source_root_issue_9170_${os.getpid()}')
+	os.rmdir_all(tmp_dir) or {}
+	defer {
+		os.rmdir_all(tmp_dir) or {}
+	}
+	project_dir := os.join_path(tmp_dir, 'project_dir')
+	source_root := os.join_path(project_dir, 'src')
+	os.mkdir_all(source_root)!
+	os.write_file(os.join_path(project_dir, 'v.mod'),
+		"Module {\n\tname: 'issue9170'\n\tbase_url: 'src'\n}\n")!
+	os.write_file(os.join_path(source_root, 'main.v'), 'module main\n')!
+	assert lookup_module_with_path('issue9170', project_dir)! == os.real_path(source_root)
+	assert lookup_module_with_path('issue9170', source_root)! == os.real_path(source_root)
+}
diff --git a/cmd/tools/vdoc/document/module.v b/cmd/tools/vdoc/document/module.v
index 8deef44da..b1122cc67 100644
--- a/cmd/tools/vdoc/document/module.v
+++ b/cmd/tools/vdoc/document/module.v
@@ -4,6 +4,50 @@ import os
 import v.ast
 import v.parser
 import v.pref
+import v.vmod
+
+fn module_path_from_vmod_root(vmod_root string, mod string) !string {
+	vmod_path := os.join_path(vmod_root, 'v.mod')
+	if !os.is_file(vmod_path) {
+		return error('module not found')
+	}
+	manifest := vmod.from_file(vmod_path)!
+	tail_path := mod_tail_after_vmod_name(mod, manifest.name)!
+	mut try_path := manifest.source_root(vmod_root)
+	if tail_path.len > 0 {
+		try_path = os.join_path(try_path, tail_path)
+	}
+	if os.is_dir(try_path) && !os.is_dir_empty(try_path) {
+		return try_path
+	}
+	return error('module not found')
+}
+
+fn module_path_from_search_root(search_path string, mod string) !string {
+	mod_path := mod.replace('.', os.path_separator)
+	try_path := os.join_path_single(search_path, mod_path)
+	if os.is_dir(try_path) && !os.is_dir_empty(try_path) {
+		return try_path
+	}
+	return module_path_from_vmod_root(search_path, mod)
+}
+
+fn mod_tail_after_vmod_name(mod string, vmod_name string) !string {
+	if vmod_name == '' {
+		return error('module not found')
+	}
+	mod_parts := mod.split('.')
+	vmod_parts := vmod_name.split('.')
+	for i := 0; i + vmod_parts.len <= mod_parts.len; i++ {
+		if i > 1 {
+			break
+		}
+		if mod_parts[i..i + vmod_parts.len].join('.') == vmod_name {
+			return mod_parts[i + vmod_parts.len..].join(os.path_separator)
+		}
+	}
+	return error('module not found')
+}
 
 // get_parent_mod returns the parent mod name, in dot format.
 // It works by climbing up the folder hierarchy, until a folder,
@@ -59,21 +103,35 @@ fn get_parent_mod(input_dir string) !string {
 pub fn lookup_module_with_path(mod string, base_path string) !string {
 	vexe := pref.vexe_path()
 	vroot := os.dir(vexe)
-	mod_path := mod.replace('.', os.path_separator)
-	compile_dir := os.real_path(base_path)
-	modules_dir := os.join_path(compile_dir, 'modules', mod_path)
-	vlib_path := os.join_path(vroot, 'vlib', mod_path)
-	mut paths := [modules_dir, vlib_path]
-	vmodules_paths := os.vmodules_paths()
-	for vmpath in vmodules_paths {
-		paths << os.join_path(vmpath, mod_path)
-	}
-	for path in paths {
-		if !os.exists(path) || os.is_dir_empty(path) {
-			continue
-		}
+	mut compile_dir := os.real_path(base_path)
+	if !os.is_dir(compile_dir) {
+		compile_dir = os.dir(compile_dir)
+	}
+	if path := module_path_from_search_root(compile_dir, mod) {
+		return path
+	}
+	modules_dir := os.join_path(compile_dir, 'modules')
+	if path := module_path_from_search_root(modules_dir, mod) {
 		return path
 	}
+	mut current_dir := compile_dir
+	for {
+		parent_dir := os.dir(current_dir)
+		if parent_dir == current_dir {
+			break
+		}
+		current_dir = parent_dir
+		if path := module_path_from_search_root(current_dir, mod) {
+			return path
+		}
+	}
+	mut search_roots := [os.join_path(vroot, 'vlib')]
+	search_roots << os.vmodules_paths()
+	for search_root in search_roots {
+		if path := module_path_from_search_root(search_root, mod) {
+			return path
+		}
+	}
 	return error('module "${mod}" not found.')
 }
 
-- 
2.39.5