[commit: ghc] master: Improve diagnostic when using `make fast` in top directory (4257570)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/42575701b5e71ec5c5e5418a4530e40e6487684c/ghc

>---------------------------------------------------------------

commit 42575701b5e71ec5c5e5418a4530e40e6487684c
Author: Victor Nawothnig <Victor.Nawothnig at gmail.de>
Date:   Sun Oct 28 12:39:05 2018 -0400

    Improve diagnostic when using `make fast` in top directory
    
    Reviewers: bgamari
    
    Reviewed By: bgamari
    
    Subscribers: rwbarton, carter
    
    Differential Revision: https://phabricator.haskell.org/D5113


>---------------------------------------------------------------

42575701b5e71ec5c5e5418a4530e40e6487684c
 Makefile | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Makefile b/Makefile
index 8046e36..73dc7ed 100644
--- a/Makefile
+++ b/Makefile
@@ -103,6 +103,7 @@ REALGOALS=$(filter-out \
     fulltest \
     slowtest \
     fasttest \
+    fast \
   ,$(MAKECMDGOALS))
 
 # configure touches certain files even if they haven't changed.  This
@@ -225,3 +226,8 @@ test:
 .PHONY: slowtest fulltest
 slowtest fulltest:
 	$(MAKE) -C testsuite/tests CLEANUP=1 SUMMARY_FILE=../../testsuite_summary.txt slow
+
+.PHONY: fast
+fast:
+	@echo "You can use 'make fast' only from inside a sub-component directory."
+	@exit 1