From bb7a0497ef41540c75183acf4ee740656aa61dd9 Mon Sep 17 00:00:00 2001
From: Ben Boeckel <ben.boeckel@kitware.com>
Date: Wed, 1 Nov 2023 12:46:17 -0400
Subject: cmTransformDepfile: warn when a depfile is not written to

---
 Source/cmTransformDepfile.cxx                          | 7 +++++++
 Tests/RunCMake/TransformDepfile/noexist-gcc-stderr.txt | 4 ++++
 2 files changed, 11 insertions(+)
 create mode 100644 Tests/RunCMake/TransformDepfile/noexist-gcc-stderr.txt

diff --git a/Source/cmTransformDepfile.cxx b/Source/cmTransformDepfile.cxx
index 914172b..ffc4de9 100644
--- a/Source/cmTransformDepfile.cxx
+++ b/Source/cmTransformDepfile.cxx
@@ -16,6 +16,9 @@
 #include "cmGccDepfileReaderTypes.h"
 #include "cmGlobalGenerator.h"
 #include "cmLocalGenerator.h"
+#include "cmMakefile.h"
+#include "cmMessageType.h"
+#include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 
 namespace {
@@ -121,6 +124,10 @@ bool cmTransformDepfile(cmDepfileFormat format, const cmLocalGenerator& lg,
       return false;
     }
     content = *std::move(result);
+  } else {
+    lg.GetMakefile()->IssueMessage(
+      MessageType::WARNING,
+      cmStrCat("Expected depfile does not exist.\n  ", infile));
   }
 
   cmSystemTools::MakeDirectory(cmSystemTools::GetFilenamePath(outfile));
diff --git a/Tests/RunCMake/TransformDepfile/noexist-gcc-stderr.txt b/Tests/RunCMake/TransformDepfile/noexist-gcc-stderr.txt
new file mode 100644
index 0000000..8956278
--- /dev/null
+++ b/Tests/RunCMake/TransformDepfile/noexist-gcc-stderr.txt
@@ -0,0 +1,4 @@
+^CMake Warning:
+  Expected depfile does not exist.
+
+    .*/Tests/RunCMake/TransformDepfile/noexist.d$
-- 
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