From 0e56b96bda57517a52ebb772d1346daf41593e3f Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Wed, 21 Oct 2020 11:06:15 +0300
Subject: [PATCH] v test-fmt: recompile vfmt only when needed

---
 cmd/tools/vtest-fmt.v | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/cmd/tools/vtest-fmt.v b/cmd/tools/vtest-fmt.v
index c3e335c2d0..2044afcb92 100644
--- a/cmd/tools/vtest-fmt.v
+++ b/cmd/tools/vtest-fmt.v
@@ -30,13 +30,7 @@ fn main() {
 
 fn v_test_formatting(vargs string) {
 	all_v_files := v_files()
-	vexe := os.getenv('VEXE')
-	vroot := os.dir(vexe)
-	recompile_result := os.system('$vexe ' + os.join_path(vroot, 'cmd', 'tools', 'vfmt.v'))
-	if recompile_result != 0 {
-		eprintln('could not recompile cmd/tools/vfmt.v')
-		exit(2)
-	}
+    prepare_vfmt_when_needed()
 	testing.eheader('Run "v fmt" over all .v files')
 	mut vfmt_test_session := testing.new_test_session('$vargs fmt -worker')
 	vfmt_test_session.files << all_v_files
@@ -60,3 +54,16 @@ fn v_files() []string {
 	}
 	return files_that_can_be_formatted
 }
+
+fn prepare_vfmt_when_needed() {
+	vexe := os.getenv('VEXE')
+	vroot := os.dir(vexe)
+	vfmtv := os.join_path(vroot, 'cmd', 'tools', 'vfmt.v')
+	if os.file_last_mod_unix(vexe) <= os.file_last_mod_unix(vfmtv) {
+		recompile_result := os.system('$vexe ' + os.join_path(vroot, 'cmd', 'tools', 'vfmt.v'))
+		if recompile_result != 0 {
+			eprintln('could not recompile cmd/tools/vfmt.v')
+			exit(2)
+		}
+	}
+}