tests: make recheck

[Akim Demaille]

commit d2a7a28438391b9f58ed334eadcd029a27e16d5e
Author: Akim Demaille <address@hidden>
Date:   Sun Oct 6 10:47:12 2019 +0200

    tests: make recheck
    
    * tests/local.mk (recheck): New.

diff --git a/README-hacking b/README-hacking
index e7cc3b19..84f2024c 100644
--- a/README-hacking
+++ b/README-hacking
@@ -229,6 +229,9 @@ To run a specific set of tests, use -k (for "keyword"). For 
example:
 Both can be combined.
   $ make check-local TESTSUITEFLAGS='-j8 -k c++'
 
+To rerun the tests that failed:
+  $ make recheck -j5
+
 ** Typical errors
 If the test suite shows failures such as the following one
 
diff --git a/tests/local.mk b/tests/local.mk
index 9f55e552..550328ea 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -94,6 +94,13 @@ clean-local: clean-local-tests
 clean-local-tests:
        test ! -f $(TESTSUITE) || $(TESTSUITE) -C %D% --clean
 
+.PHONY: recheck
+recheck: $(RUN_TESTSUITE_deps)
+       $(RUN_TESTSUITE)                                                        
\
+         $$(perl -n                                                            
\
+            -e 'if (/Summary of the failures/../Detailed failed tests/)'       
\
+            -e '{ /^ *[0-9]+:/ && s/:.*//s && print }' %D%/testsuite.log)
+
 check-local: $(RUN_TESTSUITE_deps)
        $(RUN_TESTSUITE)