make sure shasum is installed before running f-c-p/clang/setup.sh

Summary:
public
Because we ran `./configure` *after* checking if clang was to be compiled, we
could fail mysteriously if `shasum` was not present. Now, we fail at the
`./configure` step with a clear error message.

closes #275

Reviewed By: akotulski

Differential Revision: D2921841

fb-gh-sync-id: b8edd8b
shipit-source-id: b8edd8b

build-infer.sh

@@ -118,7 +118,19 @@ if [ "$BUILD_JAVA" = "yes" ]; then
 fi
 if [ "$BUILD_CLANG" = "yes" ]; then
   TARGETS+=" clang"
-  if ! facebook-clang-plugins/clang/setup.sh --only-check-install; then
+fi
+
+CONFIGURE_ARGS=
+if [ "$BUILD_CLANG" = "no" ]; then
+  CONFIGURE_ARGS+=" --disable-c-analyzers"
+fi
+if [ "$BUILD_JAVA" = "no" ]; then
+  CONFIGURE_ARGS+=" --disable-java-analyzers"
+fi
+
+./configure $CONFIGURE_ARGS
+
+if [ "$BUILD_CLANG" = "yes" ] && ! facebook-clang-plugins/clang/setup.sh --only-check-install; then
   echo ""
   echo "  Warning: you are not using a release of Infer. The C and"
   echo "  Objective-C analyses require a custom clang to be compiled"
@@ -147,26 +159,8 @@ if [ "$BUILD_CLANG" = "yes" ]; then
   if [ "x$confirm" != "xy" ]; then
     exit 0
   fi
-  fi
 fi
 
-CONFIGURE_ARGS=
-if [ "$BUILD_CLANG" = "no" ]; then
-  CONFIGURE_ARGS+=" --disable-c-analyzers"
-fi
-if [ "$BUILD_JAVA" = "no" ]; then
-  CONFIGURE_ARGS+=" --disable-java-analyzers"
-fi
-
-echo
-echo "  *************************"
-echo "  **                     **"
-echo "  **   Building Infer    **"
-echo "  **                     **"
-echo "  *************************"
-echo
-
-./configure $CONFIGURE_ARGS
 make -j $TARGETS || (
   echo
   echo '  compilation failure; you can try running'