Subject: Re: bug#10237: AM_SILENT_RULES does not work with NonStop make

From: Paul Eggert <[email-masked]>
Date: Tue, 20 Dec 2011 17:30:20 -0800

On 12/11/11 01:42, Stefano Lattarini wrote:

> I was asking for a test case that simulates the presence of a
> make implementation unable to grasp nested variable expansions

Ah, OK, revised patch enclosed below.  This patch should address
your other comments too.  Thanks for the careful review.

>From 07edd4aa81af2a8fb982427705a2009c2b7eb0bf Mon Sep 17 00:00:00 2001
From: Paul Eggert <[email-masked]>
Date: Tue, 20 Dec 2011 17:29:06 -0800
Subject: [PATCH] automake: silent-rules no longer requires nested vars

This fixes two problems reported for Automake (Bug#9928, Bug#10237)
and is in response to a bug report for building coreutils on HP
NonStop OS (Bug#10234).  The problem is that HP NonStop 'make'
treats a line like "AM_V_CC = $(am__v_CC_$(V))" as one that
expands a macro with the funny name am__v_CC_$(V instead of the
desired name am__v_CC_1 or am__v_CC_0, and since the funny macro
is not defined the line is equivalent to "AM_V_CC = )"; this
inserts a stray ")" when $(AM_V_CC) is used, which eventually
causes 'make' to fail.

The basic idea is that instead of generating Makefile.in lines like
"AM_V_CC = $(am__v_CC_$(V))", we generate
"AM_V_CC = $(am__v_CC_@AM_V@)".  We then AC_SUBST $(V) for @AM_V@
in the usual case where `make' supports nested variables,
and substitute 1 (or 0) otherwise.  Similarly for usages like
$(am__v_CC_$(AM_DEFAULT_VERBOSITY)).

With this change, make implementations that doesn't grasp nested
variable expansions will still be able to run Makefiles generated
using the silent-rules option.  They won't allow the user to
override the make verbosity at runtime through redefinition of
$(V) (as in "make V=0"); but this is still an improvement over not
being able to work at all.

* NEWS: Document this.
* automake.in (define_verbose_var): When defining the variable,
use @AM_V@ rather than $(V), and use
@AM_AM_DEFAULT_VERBOSITY@ rather than $(AM_DEFAULT_VERBOSITY).
* doc/automake.texi (Automake silent-rules Option): Explain new system.
* m4/silent.m4 (AM_SILENT_RULES): Check whether `make' supports
nested variables, and substitute AM_V and AM_AM_DEFAULT_VERBOSITY
accordingly.
* tests/silent-nested-vars.test: New file.
* tests/Makefile.am (TESTS): Add it.
* tests/Makefile.in: Regenerate.
---
 ChangeLog                     |   40 +++++++++++++++
 NEWS                          |    7 +++
 automake.in                   |    9 ++-
 doc/automake.texi             |   22 +++++----
 m4/silent.m4                  |   33 +++++++++++-
 tests/Makefile.am             |    1 +
 tests/Makefile.in             |    1 +
 tests/silent-nested-vars.test |  111 +++++++++++++++++++++++++++++++++++++++++
 8 files changed, 209 insertions(+), 15 deletions(-)
 create mode 100755 tests/silent-nested-vars.test

diff --git a/ChangeLog b/ChangeLog
index 49b6e8b..b2d6e11 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,43 @@
+2011-12-11  Paul Eggert  <[email-masked]>
+
+	automake: silent-rules no longer requires nested vars
+
+	This fixes two problems reported for Automake (Bug#9928, Bug#10237)
+	and is in response to a bug report for building coreutils on HP
+	NonStop OS (Bug#10234).  The problem is that HP NonStop 'make'
+	treats a line like "AM_V_CC = $(am__v_CC_$(V))" as one that
+	expands a macro with the funny name am__v_CC_$(V instead of the
+	desired name am__v_CC_1 or am__v_CC_0, and since the funny macro
+	is not defined the line is equivalent to "AM_V_CC = )"; this
+	inserts a stray ")" when $(AM_V_CC) is used, which eventually
+	causes 'make' to fail.
+
+	The basic idea is that instead of generating Makefile.in lines like
+	"AM_V_CC = $(am__v_CC_$(V))", we generate
+	"AM_V_CC = $(am__v_CC_@AM_V@)".  We then AC_SUBST $(V) for @AM_V@
+	in the usual case where `make' supports nested variables,
+	and substitute 1 (or 0) otherwise.  Similarly for usages like
+	$(am__v_CC_$(AM_DEFAULT_VERBOSITY)).
+
+	With this change, make implementations that doesn't grasp nested
+	variable expansions will still be able to run Makefiles generated
+	using the silent-rules option.  They won't allow the user to
+	override the make verbosity at runtime through redefinition of
+	$(V) (as in "make V=0"); but this is still an improvement over not
+	being able to work at all.
+
+	* NEWS: Document this.
+	* automake.in (define_verbose_var): When defining the variable,
+	use @AM_V@ rather than $(V), and use
+	@AM_AM_DEFAULT_VERBOSITY@ rather than $(AM_DEFAULT_VERBOSITY).
+	* doc/automake.texi (Automake silent-rules Option): Explain new system.
+	* m4/silent.m4 (AM_SILENT_RULES): Check whether `make' supports
+	nested variables, and substitute AM_V and AM_AM_DEFAULT_VERBOSITY
+	accordingly.
+	* tests/silent-nested-vars.test: New file.
+	* tests/Makefile.am (TESTS): Add it.
+	* tests/Makefile.in: Regenerate.
+
 2011-12-20  Peter Rosin  <[email-masked]>
 
 	tests: fix spurious failure on systems lacking unistd.h
diff --git a/NEWS b/NEWS
index 46803a7..58c90c9 100644
--- a/NEWS
+++ b/NEWS
@@ -74,6 +74,13 @@ Bugs fixed in 1.11.0a:
     not used, `make' output no longer contains spurious backslash-only
     lines, thus once again matching what Automake did before 1.11.
 
+  - The `silent-rules' option now generates working makefiles even for
+    the uncommon `make' implementations that do not support the
+    nested-variables extension to POSIX 2008.  For such `make'
+    implementations, whether a build is silent is determined at
+    configure time, and cannot be overridden at make time with `make
+    V=0' or `make V=1'.
+
   - The AM_COND_IF macro also works if the shell expression for the conditional
     is no longer valid for the condition.
 
diff --git a/automake.in b/automake.in
index db7f3c6..ae2011c 100755
--- a/automake.in
+++ b/automake.in
@@ -1161,9 +1161,12 @@ sub define_verbose_var ($$)
     my $silent_var = $pvar . '_0';
     if (option 'silent-rules')
       {
-	# Using `$V' instead of `$(V)' breaks IRIX make.
-	define_variable ($var, '$(' . $pvar . '_$(V))', INTERNAL);
-	define_variable ($pvar . '_', '$(' . $pvar . '_$(AM_DEFAULT_VERBOSITY))', INTERNAL);
+	# For typical `make's, `configure' replaces AM_V (inside @@) with $(V)
+	# and AM_AM_DEFAULT_VERBOSITY (inside @@) with $(AM_DEFAULT_VERBOSITY).
+	# For strict POSIX 2008 `make's, it replaces them with 0 or 1 instead.
+	# See AM_SILENT_RULES in m4/silent.m4.
+	define_variable ($var, '$(' . $pvar . '_@'.'AM_V'.'@)', INTERNAL);
+	define_variable ($pvar . '_', '$(' . $pvar . '_@'.'AM_AM_DEFAULT_VERBOSITY'.'@)', INTERNAL);
 	Automake::Variable::define ($silent_var, VAR_AUTOMAKE, '', TRUE, $val,
 				    '', INTERNAL, VAR_ASIS)
 	  if (! vardef ($silent_var, TRUE));
diff --git a/doc/automake.texi b/doc/automake.texi
index a5f857d..1a689b6 100644
--- a/doc/automake.texi
+++ b/doc/automake.texi
@@ -10130,18 +10130,20 @@ For portability to different @command{make} implementations, package authors
 are advised to not set the variable @code{V} inside the @file{Makefile.am}
 file, to allow the user to override the value for subdirectories as well.
 
-The current implementation of this feature relies on a non-POSIX, but in
-practice rather widely supported @file{Makefile} construct of nested
-variable expansion @samp{$(@var{var1}$(V))}.  Do not use the
-@option{silent-rules} option if your package needs to build with
-@command{make} implementations that do not support it.  The
-@option{silent-rules} option turns off warnings about recursive variable
-expansion, which are in turn enabled by @option{-Wportability}
-(@pxref{Invoking Automake}).
+The current implementation of this feature normally uses nested
+variable expansion @samp{$(@var{var1}$(V))}, a @file{Makefile} feature
+that is not required by POSIX 2008 but is widely supported in
+practice.  On the rare @command{make} implementations that do not
+support nested variable expansion, whether rules are silent is always
+determined at configure time, and cannot be overridden at make time.
+Future versions of POSIX are likely to require nested variable
+expansion, so this minor limitation should go away with time.
 
 @vindex @code{AM_V_GEN}
 @vindex @code{AM_V_at}
 @vindex @code{AM_DEFAULT_VERBOSITY}
+@vindex @code{AM_V}
+@vindex @code{AM_AM_DEFAULT_VERBOSITY}
 To extend the silent mode to your own rules, you have two choices:
 
 @itemize @bullet
@@ -10157,8 +10159,8 @@ The following snippet shows how you would define your own equivalent of
 @code{AM_V_GEN}:
 
 @example
-pkg_verbose = $(pkg_verbose_$(V))
-pkg_verbose_ = $(pkg_verbose_$(AM_DEFAULT_VERBOSITY))
+pkg_verbose = $(pkg_verbose_@@AM_V@@)
+pkg_verbose_ = $(pkg_verbose_@@AM_AM_DEFAULT_VERBOSITY@@)
 pkg_verbose_0 = @@echo PKG-GEN $@@;
 
 foo: foo.in
diff --git a/m4/silent.m4 b/m4/silent.m4
index 6d2a1a2..1928feb 100644
--- a/m4/silent.m4
+++ b/m4/silent.m4
@@ -1,11 +1,11 @@
 ##                                                          -*- Autoconf -*-
-# Copyright (C) 2009  Free Software Foundation, Inc.
+# Copyright (C) 2009, 2011  Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
-# serial 1
+# serial 2
 
 # AM_SILENT_RULES([DEFAULT])
 # --------------------------
@@ -20,6 +20,35 @@ yes) AM_DEFAULT_VERBOSITY=0;;
 no)  AM_DEFAULT_VERBOSITY=1;;
 *)   AM_DEFAULT_VERBOSITY=m4_if([$1], [yes], [0], [1]);;
 esac
+dnl
+dnl A few `make' implementations (e.g., NonStop OS and NextStep)
+dnl do not support nested variable expansions.
+dnl See automake bug#9928 and bug#10237.
+am_make=${MAKE-make}
+AC_CACHE_CHECK([whether $am_make supports nested variables],
+   [am_cv_make_support_nested_variables],
+   [if AS_ECHO([['TRUE=$(BAR$(V))
+BAR0=false
+BAR1=true
+V=1
+am__doit:
+	@$(TRUE)
+.PHONY: am__doit']]) | $am_make -f - >/dev/null 2>&1; then
+  am_cv_make_support_nested_variables=yes
+else
+  am_cv_make_support_nested_variables=no
+fi])
+if test $am_cv_make_support_nested_variables = yes; then
+  AM_V='$(V)'dnl Using `$V' instead of `$(V)' breaks IRIX make.
+  AM_AM_DEFAULT_VERBOSITY='$(AM_DEFAULT_VERBOSITY)'
+else
+  AM_V=$AM_DEFAULT_VERBOSITY
+  AM_AM_DEFAULT_VERBOSITY=$AM_DEFAULT_VERBOSITY
+fi
+AC_SUBST([AM_V])dnl
+AM_SUBST_NOTMAKE([AM_V])dnl
+AC_SUBST([AM_AM_DEFAULT_VERBOSITY])dnl
+AM_SUBST_NOTMAKE([AM_AM_DEFAULT_VERBOSITY])dnl
 AC_SUBST([AM_DEFAULT_VERBOSITY])dnl
 AM_BACKSLASH='\'
 AC_SUBST([AM_BACKSLASH])dnl
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 831906b..920d994 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -751,6 +751,7 @@ silent-many-gcc.test \
 silent-many-generic.test \
 silent-lex-gcc.test \
 silent-lex-generic.test \
+silent-nested-vars.test \
 silent-yacc-gcc.test \
 silent-yacc-generic.test \
 silent-configsite.test \
diff --git a/tests/Makefile.in b/tests/Makefile.in
index 3ad0146..470ed6c 100644
--- a/tests/Makefile.in
+++ b/tests/Makefile.in
@@ -1035,6 +1035,7 @@ silent-many-gcc.test \
 silent-many-generic.test \
 silent-lex-gcc.test \
 silent-lex-generic.test \
+silent-nested-vars.test \
 silent-yacc-gcc.test \
 silent-yacc-generic.test \
 silent-configsite.test \
diff --git a/tests/silent-nested-vars.test b/tests/silent-nested-vars.test
new file mode 100755
index 0000000..6716930
--- /dev/null
+++ b/tests/silent-nested-vars.test
@@ -0,0 +1,111 @@
+#!/bin/sh
+# Copyright (C) 2011 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Check silent-rules mode, on 'make' implementations that do not
+# support nested variables.
+
+. ./defs || Exit 1
+
+set -e
+
+mkdir sub
+
+cat >>configure.in <<'EOF'
+AM_SILENT_RULES
+AC_CONFIG_FILES([sub/Makefile])
+AC_PROG_CC
+AM_PROG_CC_C_O
+AC_OUTPUT
+EOF
+
+cat > Makefile.am <<'EOF'
+# Need generic and non-generic rules.
+bin_PROGRAMS = foo bar
+bar_CFLAGS = $(AM_CFLAGS)
+SUBDIRS = sub
+EOF
+
+cat > sub/Makefile.am <<'EOF'
+AUTOMAKE_OPTIONS = subdir-objects
+# Need generic and non-generic rules.
+bin_PROGRAMS = baz bla
+bla_CFLAGS = $(AM_CFLAGS)
+EOF
+
+cat > foo.c <<'EOF'
+int main ()
+{
+  return 0;
+}
+EOF
+cp foo.c bar.c
+cp foo.c sub/baz.c
+cp foo.c sub/bla.c
+
+cat >mymake <<'EOF'
+#! /bin/sh
+makerules=
+
+case $1 in
+  -f)
+    makefile=$2
+    case $2 in
+      -) makerules=`cat` || exit ;;
+    esac ;;
+  *)
+    for makefile in makefile Makefile; do
+      test -f $makefile && break
+    done ;;
+esac
+
+if printf '%s\n' "$makerules" | LC_ALL=C grep '\$([a-zA-Z0-9_]*\$' $makefile
+then
+  echo >&2 "mymake: $makefile contains nested variables"
+  exit 1
+fi
+exec $mymake_MAKE "$@"
+EOF
+chmod a+x mymake
+mymake_MAKE=${MAKE-make}
+export mymake_MAKE
+
+$ACLOCAL
+$AUTOMAKE --add-missing
+$AUTOCONF
+
+./configure --enable-silent-rules MAKE=./mymake
+./mymake >stdout || { cat stdout; Exit 1; }
+cat stdout
+$EGREP ' (-c|-o)' stdout && Exit 1
+grep 'mv ' stdout && Exit 1
+grep 'CC    .*foo\.' stdout
+grep 'CC .*bar\.' stdout
+grep 'CC .*baz\.' stdout
+grep 'CC .*bla\.' stdout
+grep 'CCLD .*foo' stdout
+grep 'CCLD .*bar' stdout
+grep 'CCLD .*baz' stdout
+grep 'CCLD .*bla' stdout
+
+./mymake clean
+./configure --disable-silent-rules MAKE=./mymake
+./mymake >stdout || { cat stdout; Exit 1; }
+cat stdout
+grep ' -c' stdout
+grep ' -o foo' stdout
+$EGREP '(CC|LD) ' stdout && Exit 1
+
+:
-- 
1.7.6.4