Discourage in-source autoconf builds (as we already do for the cmake …

…build)

http://reviews.llvm.org/D7961


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230812 91177308-0d34-0410-b5e6-96231b3b80d8

autoconf/configure.ac

@@ -73,6 +73,11 @@ if test ${srcdir} != "." ; then
   fi
 fi
 
+dnl Quit if it is an in-source build
+if test ${srcdir} == "." ; then
+  AC_MSG_ERROR([In-source builds are discouraged. Configure from a separate build directory.])
+fi
+
 dnl Default to empty (i.e. assigning the null string to) CFLAGS and CXXFLAGS,
 dnl instead of the autoconf default (for example, '-g -O2' for CC=gcc).
 : ${CFLAGS=}

configure

@@ -1999,6 +1999,12 @@ echo "$as_me: error: Already configured in ${srcdir}" >&2;}
   fi
 fi
 
+if test ${srcdir} == "." ; then
+  { { echo "$as_me:$LINENO: error: In-source builds are discouraged. Configure from a separate build directory." >&5
+echo "$as_me: error: In-source builds are discouraged. Configure from a separate build directory." >&2;}
+   { (exit 1); exit 1; }; }
+fi
+
 : ${CFLAGS=}
 : ${CXXFLAGS=}