From 582f72bf3bfaf16c1b147d4431d276f7d977aa5b Mon Sep 17 00:00:00 2001
From: Paul Elliott <paul.elliott@arm.com>
Date: Tue, 12 Jul 2022 14:55:01 +0100
Subject: [PATCH] Fix linking of generated files in cmake

If generation of files is turned off, and a file is missing, when
building in tree with cmake, you can end up with the generated file
being turned into a symlink to itself. This will also break any future
attempt at building with make. Fix this by testing if the file exists
prior to attempting to link it.

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
---
 CMakeLists.txt                  | 5 ++++-
 ChangeLog.d/fix_cmake_gen_files | 3 +++
 2 files changed, 7 insertions(+), 1 deletion(-)
 create mode 100644 ChangeLog.d/fix_cmake_gen_files

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2610359b9..ae224798c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -131,7 +131,10 @@ function(link_to_source base_name)
         set(target "${CMAKE_CURRENT_SOURCE_DIR}/${base_name}")
     endif()
 
-    if (NOT EXISTS ${link})
+    # Linking to non-existant file is not desirable. At best you will have a
+    # dangling link, but when building in tree, this can create a symbolic link
+    # to itself.
+    if (EXISTS ${target} AND NOT EXISTS ${link})
         if (CMAKE_HOST_UNIX)
             set(command ln -s ${target} ${link})
         else()
diff --git a/ChangeLog.d/fix_cmake_gen_files b/ChangeLog.d/fix_cmake_gen_files
new file mode 100644
index 000000000..3b2c09992
--- /dev/null
+++ b/ChangeLog.d/fix_cmake_gen_files
@@ -0,0 +1,3 @@
+Bugfix
+   * Fix an issue in releases with GEN_FILES turned off whereby missing
+     generated files could be turned into symlinks to themselves.