Re: [PATCH] maint.mk: generalize/improve the tight-scope rule

[Jim Meyering]

Jim Meyering wrote:
> FYI,
> Changes, in case anyone else is using this:
>   - XTERN is no longer supported, by default.
>     See the comments for how to customize it if you rely on this.
>   - you now get a diagnostic when the tight-scope syntax-check test is skipped

> Subject: [PATCH] maint.mk: generalize/improve the tight-scope rule
>
> * top/maint.mk: Emit a warning when the test is skipped.
> (_gl_TS_dir): Add $(srcdir)/ prefix.
> (_gl_TS_function_match): Simplify, rather than trying
> to enumerate common types.  Otherwise, it would fail to match an
> "extern unsigned char const *" declaration in idutils.
> (_gl_TS_extern): Do not endorse use of "XTERN", but do provide
> a way to support use of that type of macro.

First, that was incomplete.  There were two more
places in which _gl_TS_extern should be used.

Now that I've begun using the new rule via diffutils,
I've found that further changes are required.

At first, I thought to use something like this:

# GNU Makefile snippet to see if _gl_TS_headers retains its default
# in the sub-make that we'll run in the else block.
_gl_TS_mk_test = \
  ifneq ($$(_gl_TS_headers),$$(noinst_HEADERS))\n$$(error x)\nelse\nR:\nendif\n

ALL_RECURSIVE_TARGETS += sc_tight_scope
sc_tight_scope: tight-scope.mk
        @if printf '$(_gl_TS_mk_test)'                                  \
            | $(MAKE) -s -f $< -f cfg.mk -f - R                         \
          && ! grep -w noinst_HEADERS $(srcdir)/$(_gl_TS_dir)/Makefile.am \
                > /dev/null 2>&1; then                                  \
            echo '$(ME): skipping $@';                                  \
        else                                                            \
            $(MAKE) -s -C $(_gl_TS_dir)                                 \
                -f Makefile                                             \
                -f $(abs_top_srcdir)/cfg.mk                             \
                -f $(abs_top_builddir)/$<                               \
              _gl_tight_scope                                           \
                || fail=1;                                              \
        fi
        @rm -f $<

But that first test was too complicated, requiring
that cfg.mk be modified to accommodate the fact that
srcdir is not defined, yet used like this:

    include $(srcdir)/dist-check.mk

The solution is the patch below,
and to change the include to be "-"-prefixed:

    -include $(srcdir)/dist-check.mk

so that in the submake (usually from src/),
the lack of dist-check.mk doesn't cause failure
or even a diagnostic.

>From 483bd08221cccf613ae5bb5738076113150579b0 Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Mon, 23 May 2011 17:15:30 +0200
Subject: [PATCH] maint.mk: more tight_scope improvements

* top/maint.mk: (_gl_TS_var_match): Use $(_gl_TS_extern) here, too.
(_gl_TS_headers): Define only in if-0'd block.
(_gl_TS_dir): Omit the $(srcdir)/ prefix.  Sometimes we need it,
sometimes we must *not* use it.  Adjust uses accordingly.
(sc_tight_scope): Use much simpler grep-based test to determine
whether we skip this rule.
---
 ChangeLog    |    8 ++++++++
 top/maint.mk |   32 ++++++++++++++++++--------------
 2 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index f206cd4..3208380 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2011-05-23  Jim Meyering  <address@hidden>

+       maint.mk: more tight_scope improvements
+       * top/maint.mk: (_gl_TS_var_match): Use $(_gl_TS_extern) here, too.
+       (_gl_TS_headers): Define only in if-0'd block.
+       (_gl_TS_dir): Omit the $(srcdir)/ prefix.  Sometimes we need it,
+       sometimes we must *not* use it.  Adjust uses accordingly.
+       (sc_tight_scope): Use much simpler grep-based test to determine
+       whether we skip this rule.
+
        maint.mk: generalize/improve the tight-scope rule
        * top/maint.mk: Emit a warning when the test is skipped.
        (_gl_TS_dir): Add $(srcdir)/ prefix.
diff --git a/top/maint.mk b/top/maint.mk
index 58e8004..9f20900 100644
--- a/top/maint.mk
+++ b/top/maint.mk
@@ -1353,27 +1353,27 @@ update-copyright:
          $$(export VC_LIST_EXCEPT_DEFAULT=COPYING && $(VC_LIST_EXCEPT)) \
          | $(update-copyright-env) xargs $(build_aux)/$@

-# NOTE: This test is skipped with a warning if $(_gl_TS_headers) still
-# has its default value and $(_gl_TS_dir)/Makefile.am does not mention
-# noinst_HEADERS.
+# This tight_scope test is skipped with a warning if $(_gl_TS_headers) is not
+# overridden and $(_gl_TS_dir)/Makefile.am does not mention noinst_HEADERS.

 # NOTE: to override any _gl_TS_* default value, you must
 # define the variable(s) using "export" in cfg.mk.
-_gl_TS_dir ?= $(srcdir)/src
-
-# The file(s) to search for extern declarations.
-_gl_TS_headers ?= $(noinst_HEADERS)
+_gl_TS_dir ?= src

 ALL_RECURSIVE_TARGETS += sc_tight_scope
 sc_tight_scope: tight-scope.mk
-       @if test 'x$(_gl_TS_headers)' = 'x$(noinst_HEADERS)'            \
-         && ! grep -w noinst_HEADERS $(_gl_TS_dir)/Makefile.am         \
+       @if ! grep '^ *export _gl_TS_headers *=' $(srcdir)/cfg.mk       \
+               > /dev/null                                             \
+          && ! grep -w noinst_HEADERS $(srcdir)/$(_gl_TS_dir)/Makefile.am \
                > /dev/null 2>&1; then                                  \
            echo '$(ME): skipping $@';                                  \
        else                                                            \
-           $(MAKE) -s -C $(_gl_TS_dir) -f $(abs_builddir)/$<           \
-               -f Makefile _gl_tight_scope                             \
-             || fail=1;                                                \
+           $(MAKE) -s -C $(_gl_TS_dir)                                 \
+               -f Makefile                                             \
+               -f $(abs_top_srcdir)/cfg.mk                             \
+               -f $(abs_top_builddir)/$<                               \
+             _gl_tight_scope                                           \
+               || fail=1;                                              \
        fi
        @rm -f $<

@@ -1411,12 +1411,16 @@ _gl_TS_unmarked_extern_vars ?=
 # a macro like this: GLOBAL(type, var_name, initializer), then you
 # can override this definition to automatically extract those names:
 # export _gl_TS_var_match = \
-#   /^(?:extern|XTERN) .*?\**(\w+)(\[.*?\])?;/ || /\bGLOBAL\(.*?,\s*(.*?),/
-_gl_TS_var_match ?= /^(?:extern|XTERN) .*?(\w+)(\[.*?\])?;/
+#   /^(?:$(_gl_TS_extern)) .*?\**(\w+)(\[.*?\])?;/ || /\bGLOBAL\(.*?,\s*(.*?),/
+_gl_TS_var_match ?= /^(?:$(_gl_TS_extern)) .*?(\w+)(\[.*?\])?;/

 # The names of object files in (or relative to) $(_gl_TS_dir).
 _gl_TS_obj_files ?= *.$(OBJEXT)

+# Files in which to search for the one-line style extern declarations.
+# $(_gl_TS_dir)-relative.
+_gl_TS_headers ?= $(noinst_HEADERS)
+
 .PHONY: _gl_tight_scope
 _gl_tight_scope: $(bin_PROGRAMS)
        t=exceptions-$$$$;                                              \
--
1.7.5.2.1.g56b30