From ccd7c0b0e6222ca41670eb9a29cc1f9346dad772 Mon Sep 17 00:00:00 2001
From: David Bremner <david@tethera.net>
Date: Tue, 19 May 2015 22:48:24 +0200
Subject: [PATCH] configure: Add sanity checking for environment variables

Passing in environment variables incompatible with the compiler may
cause other parts of the configure script to fail in hard to
understand ways, so we abort early.
---
 configure | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index 4af7ba94..2065fcdf 100755
--- a/configure
+++ b/configure
@@ -47,6 +47,7 @@ CC=${CC:-cc}
 CXX=${CXX:-c++}
 CFLAGS=${CFLAGS:--g -O2}
 CPPFLAGS=${CPPFLAGS:-}
+CXXFLAGS_for_sh=${CXXFLAGS:-${CFLAGS}}
 CXXFLAGS=${CXXFLAGS:-\$(CFLAGS)}
 LDFLAGS=${LDFLAGS:-}
 XAPIAN_CONFIG=${XAPIAN_CONFIG:-xapian-config}
@@ -269,6 +270,35 @@ dependencies are available:
 EOF
 
 errors=0
+printf "int main(void){return 0;}\n" > minimal.c
+
+printf "Sanity checking C compilation environment... "
+if ${CC} ${CFLAGS} ${CPPFLAGS} minimal.c ${LDFLAGS} -o minimal > /dev/null 2>&1
+then
+    printf "OK.\n"
+else
+    printf "Fail.\n"
+    errors=$((errors + 1))
+fi
+
+printf "Sanity checking C++ compilation environment... "
+if ${CXX} ${CXXFLAGS_for_sh} ${CPPFLAGS} minimal.c ${LDFLAGS} -o minimal > /dev/null 2>&1
+then
+    printf "OK.\n"
+else
+    printf "Fail.\n"
+    errors=$((errors + 1))
+fi
+
+if [ $errors -gt 0 ]; then
+    cat <<EOF
+*** Error: Initial sanity checking of environment failed.  Please try
+running configure in a clean environment, and if the problem persists,
+report a bug.
+EOF
+    rm -f minimal minimal.c
+    exit 1
+fi
 
 if pkg-config --version > /dev/null 2>&1; then
     have_pkg_config=1
@@ -690,8 +720,6 @@ else
 fi
 rm -f compat/check_asctime
 
-printf "int main(void){return 0;}\n" > minimal.c
-
 printf "Checking for rpath support... "
 if ${CC} -Wl,--enable-new-dtags -Wl,-rpath,/tmp/ -o minimal minimal.c >/dev/null 2>&1
 then