[PATCH v2] configure: warn if not using a separate build directory

[Daniel P . Berrangé]

Running configure directly from the source directory is a build
configuration that will go away in future. It is also not currently
covered by any automated testing. Display a deprecation warning if
the user attempts to use an in-srcdir build setup, so that they are
aware that they're building QEMU in an undesirable manner.

Signed-off-by: Daniel P. Berrangé <address@hidden>
---

Changed in v2:

 - Use existing $source_path variable (Eric)
 - Remove bash-ism in comparison (Eric)
 - Safe quoting of directory paths (Eric)
 - Rename variables to reflect that we're applying canonicalization (Eric)

 configure | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/configure b/configure
index e225a1e3ff..5991e0e6e5 100755
--- a/configure
+++ b/configure
@@ -285,6 +285,16 @@ then
   error_exit "main directory cannot contain spaces nor colons"
 fi
 
+canon_build_path=$(realpath -- "$PWD")
+canon_source_path=$(realpath -- "$source_path")
+
+in_srcdir=no
+if [ "$canon_build_path" = "$canon_source_path" ]
+then
+    in_srcdir=yes
+fi
+
+
 # default parameters
 cpu=""
 iasl="iasl"
@@ -6799,6 +6809,23 @@ if test "$supported_os" = "no"; then
     echo "us upstream at address@hidden."
 fi
 
+if test "$in_srcdir" = "yes"; then
+    echo
+    echo "WARNING: SUPPORT FOR IN SOURCE DIR BUILDS IS DEPRECATED"
+    echo
+    echo "Support for running the 'configure' script directly from the"
+    echo "source directory is deprecated and will go away in a future"
+    echo "release. In source dir builds are not covered by automated"
+    echo "testing and are liable to break without warning. Users are"
+    echo "strongly recommended to switch to a separate build directory:"
+    echo
+    echo "  $ mkdir build"
+    echo "  $ cd build"
+    echo "  $ ../configure"
+    echo "  $ make"
+    echo
+fi
+
 config_host_mak="config-host.mak"
 
 echo "# Automatically generated by configure - do not modify" 
>config-all-disas.mak
-- 
2.24.1