[Automake-ng] [PATCH] [ng] dry run: only use GNU make builtins to determine whether running dry

[Stefano Lattarini]

* lib/am/header-vars.am (am__make_dryrun): only use GNU make builtins to
determine whether make is being running in "dry mode".
* t/nodep.sh: Adjust grepping checks to avoid spurious failures.

Signed-off-by: Stefano Lattarini <address@hidden>
---

 I will push by this evening if there is no objection.

 Regards,
   Stefano

 lib/am/header-vars.am |   41 +++++++++++++++--------------------------
 t/nodep.sh            |    2 +-
 2 files changed, 16 insertions(+), 27 deletions(-)

diff --git a/lib/am/header-vars.am b/lib/am/header-vars.am
index f6ae460..40aa13f 100644
--- a/lib/am/header-vars.am
+++ b/lib/am/header-vars.am
@@ -29,32 +29,21 @@ am__vpath_rewrite = \
 ## a vendor make.
 ## DESTDIR =
 
-## Shell code that determines whether make is running in "dry mode"
-## ("make -n") or not.  Useful in rules that invoke make recursively, and
-## are thus executed also with "make -n" -- because, say, their recipes
-## contain the "$(MAKE)" string or starts with the '+' modifier.
-am__make_dryrun = \
-  { \
-    am__dry=no; \
-    case $$MAKEFLAGS in \
-## If we run "make TESTS='snooze nap'", GNU make will export MAKEFLAGS
-## to "TESTS=foo\ nap", so that the simpler loop below (on word-splitted
-## $$MAKEFLAGS) would see a "make flag" equal to "nap", and would wrongly
-## misinterpret that as and indication that make is running in dry mode.
-## This has already happened in practice.  So we need this hack.
-      *\\[\ \  ]*) \
-        echo 'am--echo: ; @echo "AM"  OK' | $(MAKE) -f - 2>/dev/null \
-          | grep '^AM OK$$' >/dev/null || am__dry=yes;; \
-      *) \
-        for am__flg in $$MAKEFLAGS; do \
-          case $$am__flg in \
-            *=*|--*) ;; \
-            *n*) am__dry=yes; break;; \
-          esac; \
-        done;; \
-    esac; \
-    test $$am__dry = yes; \
-  }
+## Tell whether make is running in "dry mode".  It is either 'true' or
+## 'false', so that it can be easily used in shell code as well as in
+## GNU make conditionals.
+## If we run "make TESTS='snooze nap'", GNU make will export MAKEFLAGS to
+## "TESTS=foo\ nap", so that the builtins operating on word-split lists
+## would see a "make flag" equal to "nap" when analyzing $(MAKEFLAGS), and
+## would wrongly misinterpret that as and indication that make is running
+## in dry mode.  This has already happened in practice.  So we need the
+## hack with $(subst \, ...).
+am__make_dryrun := \
+  $(strip $(if $(strip \
+    $(foreach am__v, $(subst \ ,,$(strip $(MAKEFLAGS))), \
+      $(if $(or $(findstring =,$(am__v)),$(filter --%,$(am__v))),, \
+        $(findstring n,$(am__v))))), \
+    true, false))
 
 ## Some derived variables that have been found to be useful.
 pkgdatadir = $(datadir)/@PACKAGE@
diff --git a/t/nodep.sh b/t/nodep.sh
index 5dcad1c..1002c54 100755
--- a/t/nodep.sh
+++ b/t/nodep.sh
@@ -36,5 +36,5 @@ mkdir x
 $ACLOCAL
 $AUTOMAKE
 
-grep '%' Makefile.in && Exit 1
+$FGREP -v '$(filter --%,' Makefile.in | grep '%' && Exit 1
 Exit 0
-- 
1.7.9.5