Work around <=m4-1.4.9 bug in m4_format.

* lib/m4sugar/m4sugar.m4 (_m4_index): New internal macro.
(m4_init): Only use it in older m4.
* lib/autoconf/general.m4 (_AC_DEFINE_Q): Use it to avoid
m4_format bug in older m4.
* lib/autoconf/status.m4 (_AC_CONFIG_COMPUTE_DEST): Likewise.
Reported by Bob Proulx.

Signed-off-by: Eric Blake <ebb9@byu.net>

diff --git a/ChangeLog b/ChangeLog
index 2367c7c7e8e26b270229c827149ed088a0787fa3..b28abcdf0361aa6562168bd669b7b625081ddf08 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2008-11-10  Eric Blake  <ebb9@byu.net>
+
+       Work around <=m4-1.4.9 bug in m4_format.
+       * lib/m4sugar/m4sugar.m4 (_m4_index): New internal macro.
+       (m4_init): Only use it in older m4.
+       * lib/autoconf/general.m4 (_AC_DEFINE_Q): Use it to avoid
+       m4_format bug in older m4.
+       * lib/autoconf/status.m4 (_AC_CONFIG_COMPUTE_DEST): Likewise.
+       Reported by Bob Proulx.
+
 2008-11-10  Eric Blake  <ebb9@byu.net>
 
        Match upstream standards.texi.

diff --git a/lib/autoconf/general.m4 b/lib/autoconf/general.m4
index 2c184fc4d984f88550aa3b530abef88ebc4ae490..15377cbea9dedce327dd2b24fd4f68959ce636df 100644 (file)
--- a/lib/autoconf/general.m4
+++ b/lib/autoconf/general.m4
@@ -2077,8 +2077,10 @@ m4_define([AC_DEFINE_UNQUOTED], [_AC_DEFINE_Q([], $@)])
 # m4_format rather than regex to grab prefix up to first ().  AC_name
 # is defined with over-quotation, so that we can avoid m4_defn; this
 # is only safe because the name should not contain $.
+#
+# Use _m4_index to avoid a bug in m4_format in older m4.
 m4_define([_AC_DEFINE_Q],
-[m4_pushdef([AC_name], m4_format([[[%.*s]]], m4_index([$2], [(]), [$2]))]dnl
+[m4_pushdef([AC_name], m4_format([[[%.*s]]], _m4_index([$2], [(]), [$2]))]dnl
 [AC_DEFINE_TRACE(AC_name)]dnl
 [m4_cond([m4_index([$3], [
 ])], [-1], [],

diff --git a/lib/autoconf/status.m4 b/lib/autoconf/status.m4
index 388b90f263f18206379757f63ca467e6a5ce81f4..c134bb7b5ac109b0556ff03e6f126ac1632db081 100644 (file)
--- a/lib/autoconf/status.m4
+++ b/lib/autoconf/status.m4
@@ -247,9 +247,9 @@ m4_define([_AC_CONFIG_FOOS],
 # _AC_CONFIG_COMPUTE_DEST(STRING)
 # -------------------------------
 # Compute the DEST from STRING by stripping any : and following
-# characters.
+# characters.  Use _m4_index to avoid a bug in m4_format in older m4.
 m4_define([_AC_CONFIG_COMPUTE_DEST],
-[m4_format([[%.*s]], m4_index([$1], [:]), [$1])])
+[m4_format([[%.*s]], _m4_index([$1], [:]), [$1])])
 
 # _AC_CONFIG_REGISTER(MODE, TAG, [COMMANDS])
 # ------------------------------------------

diff --git a/lib/m4sugar/m4sugar.m4 b/lib/m4sugar/m4sugar.m4
index 2a0d7ceed1d946c8997b95f5d4c528a238effc21..88847147b34e02b2cfeb502c8c8f64195887bf3d 100644 (file)
--- a/lib/m4sugar/m4sugar.m4
+++ b/lib/m4sugar/m4sugar.m4
@@ -625,6 +625,22 @@ m4_define([m4_dumpdefs],
        [m4_map_args([$0], $@)])])
 
 
+# _m4_index(HAYSTACK, NEEDLE)
+# ---------------------------
+# Like the original, except return -2 instead of -1 if NEEDLE is not
+# present in HAYSTACK.  That way, it can be used to work around a bug
+# in m4 1.4.9 and earlier where m4_format did not accept a precision
+# of -1; this macro can be safely used in the idiom:
+#   m4_format([[%.*s]], _m4_index([$1],[$2]), [$1])
+# to grab the prefix of $1 up to but excluding $2, if it was present,
+# otherwise the entire $1.
+m4_define([_m4_index],
+[$0_(m4_index($@))])
+
+m4_define([_m4_index_],
+[m4_if([$1], [-1], [-2], [$1])])
+
+
 # m4_popdef(NAME)
 # ---------------
 # Like the original, except guarantee a warning when using something which is
@@ -2975,7 +2991,8 @@ m4_pattern_forbid([^dnl$])
 
 # If __m4_version__ is defined, we assume that we are being run by M4
 # 1.6 or newer, and thus that $@ recursion is linear and debugmode(d)
-# is available for faster checks of dereferencing undefined macros.
+# is available for faster checks of dereferencing undefined macros,
+# and we don't need to worry about _m4_format bugs with _m4_index.
 # But if it is missing, we assume we are being run by M4 1.4.x, that
 # $@ recursion is quadratic, and that we need foreach-based
 # replacement macros.  Use the raw builtin to avoid tripping up
@@ -2983,9 +3000,10 @@ m4_pattern_forbid([^dnl$])
 # undefines m4_defn.
 m4_ifdef([__m4_version__],
 [m4_debugmode([+d])
-m4_define([m4_defn], _m4_defn([m4_defn]))
-m4_define([m4_popdef], _m4_defn([m4_popdef]))
-m4_define([m4_undefine], _m4_defn([m4_undefine]))],
+m4_define([m4_defn], _m4_defn([_m4_defn]))
+m4_define([_m4_index], _m4_defn([m4_index]))
+m4_define([m4_popdef], _m4_defn([_m4_popdef]))
+m4_define([m4_undefine], _m4_defn([_m4_undefine]))],
 [m4_builtin([include], [m4sugar/foreach.m4])])
 
 # Rewrite the first entry of the diversion stack.