From fd3be6ccc0576edf0a74b9f312f8308482b7dd9c Mon Sep 17 00:00:00 2001
From: Sergey Matveev <stargrave@stargrave.org>
Date: Tue, 12 Jan 2021 21:29:08 +0300
Subject: [PATCH] Output-less target as a dependency

---
 dep.go               | 36 ++++++++++++++++++++----------------
 doc/news.texi        |  6 ++++--
 t/goredo-deps.t      |  1 +
 t/goredo-empty-dep.t | 24 ++++++++++++++++++++++++
 usage.go             |  2 +-
 5 files changed, 50 insertions(+), 19 deletions(-)
 create mode 100755 t/goredo-empty-dep.t

diff --git a/dep.go b/dep.go
index 0c5b634..d7c874a 100644
--- a/dep.go
+++ b/dep.go
@@ -123,30 +123,34 @@ func writeDep(fdDep *os.File, cwd, tgt string) error {
 	)
 }
 
-func writeDeps(fdDep *os.File, tgts []string) error {
+func writeDeps(fdDep *os.File, tgts []string) (err error) {
 	if fdDep == nil {
 		trace(CDebug, "no opened fdDep: %s", tgts)
 		return nil
 	}
 	for _, tgt := range tgts {
-		if _, err := os.Stat(tgt); err == nil {
-			tgtAbs, err := filepath.Abs(tgt)
-			if err != nil {
-				panic(err)
-			}
-			tgtDir := path.Join(Cwd, DirPrefix)
-			tgtRel, err := filepath.Rel(tgtDir, tgtAbs)
-			if err != nil {
-				panic(err)
-			}
-			if err = writeDep(fdDep, tgtDir, tgtRel); err != nil {
-				return err
-			}
+		tgtAbs, err := filepath.Abs(tgt)
+		if err != nil {
+			panic(err)
+		}
+		tgtDir := path.Join(Cwd, DirPrefix)
+		tgtRel, err := filepath.Rel(tgtDir, tgtAbs)
+		if err != nil {
+			panic(err)
+		}
+		if _, errStat := os.Stat(tgt); errStat == nil {
+			err = writeDep(fdDep, tgtDir, tgtRel)
 		} else {
-			trace(CDebug, "skipping dep record, can not stat: %s", tgt)
+			trace(CDebug, "ifchange: %s <- %s (unexisting)", fdDep.Name(), tgtRel)
+			err = recfileWrite(
+				fdDep,
+				recfile.Field{Name: "Type", Value: DepTypeIfchange},
+				recfile.Field{Name: "Target", Value: tgtRel},
+				recfile.Field{Name: "Ctime", Value: "0.0"},
+			)
 		}
 	}
-	return nil
+	return
 }
 
 type DepInfo struct {
diff --git a/doc/news.texi b/doc/news.texi
index 3504e46..8955eab 100644
--- a/doc/news.texi
+++ b/doc/news.texi
@@ -1,9 +1,11 @@
 @node News
 @unnumbered News
 
-@anchor{Release 0.11.1}
-@section Release 0.11.1
+@anchor{Release 0.12.0}
+@section Release 0.12.0
 @itemize
+@item
+    Do not forget to save even output-less target as a dependency.
 @item
     @option{-debug} option renamed to shorter @option{-d}.
 @end itemize
diff --git a/t/goredo-deps.t b/t/goredo-deps.t
index a0a58d5..2e3ca5e 100755
--- a/t/goredo-deps.t
+++ b/t/goredo-deps.t
@@ -6,6 +6,7 @@ test_description="Check that the following use-case won't rebuild everytime and
 
 tmp=`mktemp -d`
 trap "rm -fr $tmp" HUP PIPE INT QUIT TERM EXIT
+
 cd $tmp
 mkdir -p sub
 cat > default.html.do <<EOF
diff --git a/t/goredo-empty-dep.t b/t/goredo-empty-dep.t
new file mode 100755
index 0000000..1b4a6d2
--- /dev/null
+++ b/t/goredo-empty-dep.t
@@ -0,0 +1,24 @@
+#!/bin/sh
+
+testname=`basename "$0"`
+test_description="Check that empty target is a dependency and always OOD"
+. $SHARNESS_TEST_SRCDIR/sharness.sh
+
+tmp=`mktemp -d`
+trap "rm -fr $tmp" HUP PIPE INT QUIT TERM EXIT
+cd $tmp
+
+echo > foo.do
+cat > bar.do <<EOF
+redo-ifchange foo
+echo bar
+EOF
+export REDO_NO_PROGRESS=1
+redo-ifchange bar
+stat1=`stat bar`
+redo-ifchange bar
+stat2=`stat bar`
+
+test_expect_success "bar rebuilds" '[ "$stat1" != "$stat2" ]'
+
+test_done
diff --git a/usage.go b/usage.go
index af660db..cbbb672 100644
--- a/usage.go
+++ b/usage.go
@@ -26,7 +26,7 @@ import (
 )
 
 const (
-	Version  = "0.11.1"
+	Version  = "0.12.0"
 	Warranty = `This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, version 3 of the License.
-- 
2.44.0