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[SCM] GNU Autoconf source repository branch, master, updated. v2.63b-20-
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From: |
Eric Blake |
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Subject: |
[SCM] GNU Autoconf source repository branch, master, updated. v2.63b-20-ge9a5c22 |
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Date: |
Tue, 14 Apr 2009 12:57:52 +0000 |
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- Log -----------------------------------------------------------------
commit e9a5c2211af530705faca81f97bcd245de362154
Author: Eric Blake <address@hidden>
Date: Fri Apr 10 14:43:33 2009 -0600
Improve documentation related to expanded-before-required.
* doc/autoconf.texi (Expanded Before Required): Add a case study.
(Running the Compiler) <AC_COMPILE_IFELSE>: Remind users that
running a compile test will AC_REQUIRE the compiler check.
(Macro Definitions) <AC_DEFUN>: Contrast AC_DEFUN and m4_define.
(C Compiler) <AC_PROG_CC>: Mention the fact that only first
invocation of this macro checks for $EXEEXT, and that many other
macros use it via AC_REQUIRE.
Reported by Andreas Schwab.
Signed-off-by: Eric Blake <address@hidden>
commit d7f226ee0b85088148d55a51b489b01215beba52
Author: Eric Blake <address@hidden>
Date: Fri Apr 10 10:56:40 2009 -0600
Mention latest rules about make and set -e.
* doc/autoconf.texi (Failure in Make Rules): Posix is now clear
that make must use set -e.
(Limitations of Builtins) <set>: Clarify more about set -e
behavior.
Signed-off-by: Eric Blake <address@hidden>
commit 0cd7cde0607fff469ac42f173e36c2dd8aad7ea3
Author: Eric Blake <address@hidden>
Date: Thu Apr 9 22:33:37 2009 -0600
Improve documentation about if exit status.
* doc/autoconf.texi (Limitations of Builtins) <if>: Mention that
exit status bugs don't affect modern targets.
Reported by Andreas Schwab.
Signed-off-by: Eric Blake <address@hidden>
commit ff97bd9a3f2649a407dccf3ca0cb8f890264aa68
Author: Eric Blake <address@hidden>
Date: Thu Apr 9 23:00:22 2009 -0600
Add cross-reference to new macros.
* doc/autoconf.texi (Text processing Macros) <m4_normalize>
<m4_strip>: Reference the new m4_ifblank.
Suggested by Mike Frysinger.
Signed-off-by: Eric Blake <address@hidden>
commit 52b83b8c374080dceeaeec57b80a6ed0d2b3d38f
Author: Eric Blake <address@hidden>
Date: Thu Apr 9 21:45:18 2009 -0600
Make AS_IF, AS_CASE, and AS_FOR more robust to blank arguments.
* lib/m4sugar/m4sh.m4 (_AS_CASE, _AS_CASE_DEFAULT, AS_FOR, _AS_IF)
(_AS_IF_ELSE, AS_IF): Avoid syntax error on blank argument,
including a macro with an empty expansion.
* NEWS: Mention this.
* tests/m4sh.at (AS@&address@hidden and AS@&address@hidden,
AS@&address@hidden): Update
tests.
Reported by Mike Frysinger.
Signed-off-by: Eric Blake <address@hidden>
commit 723c9e5c0f2c3aa7ef46534ad084974fa2282435
Author: Eric Blake <address@hidden>
Date: Thu Apr 9 07:05:00 2009 -0600
Add m4_blank and friends.
* lib/m4sugar/m4sugar.m4 (m4_blank, m4_nblank, m4_default_nblank)
(m4_default_nblank_quoted): New macros.
* NEWS: Document them.
* doc/autoconf.texi (Conditional constructs): Likewise.
* tests/m4sugar.at (m4sugar shorthand conditionals): New test.
Suggested by Mike Frysinger.
Signed-off-by: Eric Blake <address@hidden>
-----------------------------------------------------------------------
Summary of changes:
ChangeLog | 45 +++++++++
NEWS | 6 +
doc/autoconf.texi | 247 +++++++++++++++++++++++++++++++++++++++++++-----
lib/m4sugar/m4sh.m4 | 29 +++---
lib/m4sugar/m4sugar.m4 | 47 ++++++++-
tests/m4sh.at | 11 ++-
tests/m4sugar.at | 85 +++++++++++++++++
7 files changed, 428 insertions(+), 42 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index efa2056..c1894d9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,50 @@
2009-04-13 Eric Blake <address@hidden>
+ Improve documentation related to expanded-before-required.
+ * doc/autoconf.texi (Expanded Before Required): Add a case study.
+ (Running the Compiler) <AC_COMPILE_IFELSE>: Remind users that
+ running a compile test will AC_REQUIRE the compiler check.
+ (Macro Definitions) <AC_DEFUN>: Contrast AC_DEFUN and m4_define.
+ (C Compiler) <AC_PROG_CC>: Mention the fact that only first
+ invocation of this macro checks for $EXEEXT, and that many other
+ macros use it via AC_REQUIRE.
+ Reported by Andreas Schwab.
+
+ Mention latest rules about make and set -e.
+ * doc/autoconf.texi (Failure in Make Rules): Posix is now clear
+ that make must use set -e.
+ (Limitations of Builtins) <set>: Clarify more about set -e
+ behavior.
+
+ Improve documentation about if exit status.
+ * doc/autoconf.texi (Limitations of Builtins) <if>: Mention that
+ exit status bugs don't affect modern targets.
+ Reported by Andreas Schwab.
+
+ Add cross-reference to new macros.
+ * doc/autoconf.texi (Text processing Macros) <m4_normalize>
+ <m4_strip>: Reference the new m4_ifblank.
+ Suggested by Mike Frysinger.
+
+ Make AS_IF, AS_CASE, and AS_FOR more robust to blank arguments.
+ * lib/m4sugar/m4sh.m4 (_AS_CASE, _AS_CASE_DEFAULT, AS_FOR, _AS_IF)
+ (_AS_IF_ELSE, AS_IF): Avoid syntax error on blank argument,
+ including a macro with an empty expansion.
+ * NEWS: Mention this.
+ * tests/m4sh.at (AS@&address@hidden and AS@&address@hidden,
AS@&address@hidden): Update
+ tests.
+ Reported by Mike Frysinger.
+
+ Add m4_blank and friends.
+ * lib/m4sugar/m4sugar.m4 (m4_blank, m4_nblank, m4_default_nblank)
+ (m4_default_nblank_quoted): New macros.
+ * NEWS: Document them.
+ * doc/autoconf.texi (Conditional constructs): Likewise.
+ * tests/m4sugar.at (m4sugar shorthand conditionals): New test.
+ Suggested by Mike Frysinger.
+
+2009-04-13 Eric Blake <address@hidden>
+
Finish upgrade to GFDL 1.3.
* doc/autoconf.texi (copying): Use correct license; comment change
was missed on 2008-11-04.
diff --git a/NEWS b/NEWS
index e91fc39..8eb3a06 100644
--- a/NEWS
+++ b/NEWS
@@ -3,10 +3,16 @@ GNU Autoconf NEWS - User visible changes.
* Major changes in Autoconf 2.64 (2009-??-??) [stable]
Released by Eric Blake, based on git versions 2.63b.*.
+** AS_IF, AS_CASE, and AS_FOR have been taught to avoid syntax errors
+ even when given arguments that expand to just whitespace.
+
** Ensure AT_CHECK can support commands that include a # given with
proper m4 quoting. For shell comments, this is a new feature; for
non-shell comments, this fixes a regression introduced in 2.63b.
+** The following documented m4sugar macros are new:
+ m4_default_nblank m4_default_nblank_quoted m4_ifblank m4_ifnblank
+
* Major changes in Autoconf 2.63b (2009-03-31) [beta]
Released by Eric Blake, based on git versions 2.63.*.
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 8dd22d6..38b0972 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -6737,6 +6737,15 @@ If using the @acronym{GNU} C compiler, set shell
variable @code{GCC} to
it to @option{-g -O2} for the @acronym{GNU} C compiler (@option{-O2} on systems
where @acronym{GCC} does not accept @option{-g}), or @option{-g} for
other compilers.
+
+Many Autoconf macros use a compiler, and thus call
address@hidden([AC_PROG_CC])} to ensure that the compiler has been
+determined before the body of the outermost @code{AC_DEFUN} macro.
+Although @code{AC_PROG_CC} is safe to directly expand multiple times, it
+performs certain checks (such as the proper value of @env{EXEEXT}) only
+on the first invocation. Therefore, care must be used when invoking
+this macro from within another macro rather than at the top level
+(@pxref{Expanded Before Required}).
@end defmac
@anchor{AC_PROG_CC_C_O}
@@ -8371,6 +8380,12 @@ It is customary to report unexpected failures with
@code{AC_MSG_FAILURE}. This macro does not try to link; use
@code{AC_LINK_IFELSE} if you need to do that (@pxref{Running the
Linker}).
+
+This macro uses @code{AC_REQUIRE} for the compiler associated with the
+current language, which means that if the compiler has not yet been
+determined, the compiler determination will be made prior to the body of
+the outermust @code{AC_DEFUN} macro that triggered this macro to
+expand (@pxref{Expanded Before Required}).
@end defmac
@ovindex ERL
@@ -10988,25 +11003,74 @@ m4_cond([m4_index([$1], [\])], [-1], [$2],
@defmac m4_default (@var{expr-1}, @var{expr-2})
@defmacx m4_default_quoted (@var{expr-1}, @var{expr-2})
address@hidden m4_default_nblank (@var{expr-1}, @ovar{expr-2})
address@hidden m4_default_nblank_quoted (@var{expr-1}, @ovar{expr-2})
@msindex{default}
@msindex{default_quoted}
-If @var{expr-1} is not empty, use it. Otherwise, select @var{expr-2}.
address@hidden
address@hidden
+If @var{expr-1} contains text, use it. Otherwise, select @var{expr-2}.
@code{m4_default} expands the result, while @code{m4_default_quoted}
does not. Useful for providing a fixed default if the expression that
-results in @var{expr-1} would otherwise be empty.
+results in @var{expr-1} would otherwise be empty. The difference
+between @code{m4_default} and @code{m4_default_nblank} is whether an
+argument consisting of just blanks (space, tab, newline) is
+significant. When using the expanding versions, note that an argument
+may contain text but still expand to an empty string.
@example
m4_define([active], [ACTIVE])dnl
+m4_define([empty], [])dnl
m4_define([demo1], [m4_default([$1], [$2])])dnl
m4_define([demo2], [m4_default_quoted([$1], [$2])])dnl
+m4_define([demo3], [m4_default_nblank([$1], [$2])])dnl
+m4_define([demo4], [m4_default_nblank_quoted([$1], [$2])])dnl
demo1([active], [default])
@result{}ACTIVE
demo1([], [active])
@result{}ACTIVE
+demo1([empty], [text])
address@hidden
+-demo1([ ], [active])-
address@hidden -
demo2([active], [default])
@result{}active
demo2([], [active])
@result{}active
+demo2([empty], [text])
address@hidden
+-demo2([ ], [active])-
address@hidden -
+demo3([active], [default])
address@hidden
+demo3([], [active])
address@hidden
+demo3([empty], [text])
address@hidden
+-demo3([ ], [active])-
address@hidden
+demo4([active], [default])
address@hidden
+demo4([], [active])
address@hidden
+demo4([empty], [text])
address@hidden
+-demo4([ ], [active])-
address@hidden
address@hidden example
address@hidden defmac
+
address@hidden m4_ifblank (@var{cond}, @ovar{if-blank}, @ovar{if-text})
address@hidden m4_ifnblank (@var{cond}, @ovar{if-text}, @ovar{if-blank})
address@hidden
address@hidden
+If @var{cond} is empty or consists only of blanks (space, tab, newline),
+then expand @var{if-blank}; otherwise, expand @var{if-text}. Two
+variants exist, in order to make it easier to select the correct logical
+sense when using only two parameters. Note that this is more efficient
+than the equivalent behavior of:
address@hidden
+m4_ifval(m4_normalize(address@hidden), @var{if-text}, @var{if-cond})
@end example
@end defmac
@@ -11762,7 +11826,9 @@ that M4 does not discard leading whitespace during
argument collection.
Remove leading and trailing spaces and tabs, sequences of
backslash-then-newline, and replace multiple spaces, tabs, and newlines
with a single space. This is a combination of @code{m4_flatten} and
address@hidden
address@hidden To determine if @var{string} consists only of bytes
+that would be removed by @code{m4_normalize}, you can use
address@hidden
@end defmac
@defmac m4_re_escape (@var{string})
@@ -11785,7 +11851,8 @@ Strip whitespace from @var{string}. Sequences of
spaces and tabs are
reduced to a single space, then leading and trailing spaces are removed.
The result is still a quoted string. Note that this does not interfere
with newlines; if you want newlines stripped as well, consider
address@hidden, or do it all at once with @code{m4_normalize}.
address@hidden, or do it all at once with @code{m4_normalize}. To
+quickly test if @var{string} has only whitespace, use @code{m4_ifblank}.
@end defmac
@defmac m4_text_box (@var{message}, @dvar{frame, -})
@@ -12945,6 +13012,24 @@ Keep in mind that @code{dnl} is rarely needed to
introduce comments;
@code{dnl} is more useful to get rid of the newlines following macros
that produce no output, such as @code{AC_REQUIRE}.
+Public third-party macros need to use @code{AC_DEFUN}, and not
address@hidden, in order to be found by @command{aclocal}
+(@pxref{Extending aclocal,,, automake, @acronym{GNU} Automake}).
+Additionally, if it is ever determined that a macro should be made
+obsolete, it is easy to convert from @code{AC_DEFUN} to @code{AU_DEFUN}
+in order to have @command{autoupdate} assist the user in choosing a
+better alternative, but there is no corresponding way to make
address@hidden issue an upgrade notice (@pxref{AU_DEFUN}).
+
+There is another subtle, but important, difference between using
address@hidden and @code{AC_DEFUN}: only the former is unaffected by
address@hidden When writing a file, it is always safe to replace a
+block of text with a @code{m4_define} macro that will expand to the same
+text. But replacing a block of text with an @code{AC_DEFUN} macro with
+the same content does not necessarily give the same results, because it
+changes the location where any embedded but unsatisfied
address@hidden invocations within the block will be expanded. For an
+example of this, see @ref{Expanded Before Required}.
@node Macro Names
@section Macro Names
@@ -15784,7 +15869,8 @@ AS_IF([cmp -s file file.new], [], [mv file.new file])
This is especially useful in other M4 macros, where the @dfn{then} and
@dfn{else} branches might be macro arguments.
-There are shells that do not reset the exit status from an @command{if}:
+Some very old shells did not reset the exit status from an @command{if}
+with no @command{else}:
@example
$ @kbd{if (exit 42); then true; fi; echo $?}
@@ -15792,9 +15878,10 @@ $ @kbd{if (exit 42); then true; fi; echo $?}
@end example
@noindent
-whereas a proper shell should have printed @samp{0}. This is especially
-bad in makefiles since it produces false failures. This is why properly
-written makefiles, such as Automake's, have such hairy constructs:
+whereas a proper shell should have printed @samp{0}. But this is no
+longer a portability problem; any shell that supports functions gets it
+correct. However, it explains why some makefiles have lengthy
+constructs:
@example
if test -f "$file"; then
@@ -15917,16 +16004,42 @@ better to combine them:
set -ex
@end example
address@hidden @command{set -e}
+The option @option{-e} has historically been underspecified, with enough
+ambiguities to cause numerous differences across various shell
+implementations. Perhaps the best reference is
address@hidden://www.opengroup.org/@/austin/@/mailarchives/@/ag-review/@/msg03507.html,
+this link}, recommending a change to Posix 2008 to match @command{ksh88}
+behavior. Note that mixing @code{set -e} and shell functions is asking
+for surprises:
+
address@hidden
+set -e
+doit()
address@hidden
+ rm file
+ echo one
address@hidden
+doit || echo two
address@hidden example
+
address@hidden
+According to the recommendation, @samp{one} should always be output
+regardless of whether the @command{rm} failed, because it occurs within
+the body of the shell function @samp{doit} invoked on the left side of
address@hidden||}, where the effects of @samp{set -e} are not enforced.
+Likewise, @samp{two} should never be printed, since the failure of
address@hidden does not abort the function, such that the status of
address@hidden is 0.
+
The @acronym{BSD} shell has had several problems with the @option{-e}
-option, partly because @acronym{BSD} @command{make} traditionally used
address@hidden even though this was incompatible with Posix
-(@pxref{Failure in Make Rules}). Older versions of the @acronym{BSD}
+option. Older versions of the @acronym{BSD}
shell (circa 1990) mishandled @samp{&&}, @samp{||}, @samp{if}, and
@samp{case} when @option{-e} was in effect, causing the shell to exit
unexpectedly in some cases. This was particularly a problem with
makefiles, and led to circumlocutions like @samp{sh -c 'test -f file ||
touch file'}, where the seemingly-unnecessary @samp{sh -c '@dots{}'}
-wrapper works around the bug.
+wrapper works around the bug (@pxref{Failure in Make Rules}).
Even relatively-recent versions of the @acronym{BSD} shell (e.g.,
address@hidden 3.4) wrongly exit with @option{-e} if a command within
@@ -17446,16 +17559,15 @@ later) @command{make} diagnoses these uses and errors
out.
@node Failure in Make Rules
@section Failure in Make Rules
-Since 1992 Posix has required that @command{make} must invoke
-each command with the equivalent of a @samp{sh -c} subshell. However,
-many @command{make} implementations, including @acronym{BSD} make through 2004,
-use @samp{sh -e -c} instead, and the @option{-e} option causes the
-subshell to exit immediately if a subsidiary simple-command fails. For
-example, the command @samp{touch T; rm -f U} always attempts to
-remove @file{U} with Posix make, but incompatible
address@hidden implementations skip the @command{rm} if the
address@hidden fails. One way to work around this is to reword the
-affected simple-commands so that they always succeed, e.g., @samp{touch
+Posix 2008 requires that @command{make} must invoke each command with
+the equivalent of a @samp{sh -e -c} subshell, which causes the
+subshell to exit immediately if a subsidiary simple-command fails,
+although not all @command{make} implementations have historically
+followed this rule. For
+example, the command @samp{touch T; rm -f U} may attempt to
+remove @file{U} even if the @command{touch} fails, although this is not
+permitted with Posix make. One way to work around failures in simple
+commands is to reword them so that they always succeed, e.g., @samp{touch
T || :; rm -f U}.
However, even this approach can run into common bugs in @acronym{BSD}
implementations of the @option{-e} option of @command{sh} and
@@ -23031,6 +23143,97 @@ by arguments or by the current definition of other
macros in the m4
environment, then the macro should always be directly expanded instead
of required.
+For another case study, consider this example trimmed down from an
+actual package. Originally, the package contained shell code and
+multiple macro invocations at the top level of @file{configure.ac}:
+
address@hidden
+AC_DEFUN([FOO], [AC_COMPILE_IFELSE(address@hidden)])
+foobar=
+AC_PROG_CC
+FOO
address@hidden example
+
address@hidden
+but that was getting complex, so the author wanted to offload some of
+the text into a new macro in another file included via
address@hidden The na@"ive approach merely wraps the text in a new
+macro:
+
address@hidden
+AC_DEFUN([FOO], [AC_COMPILE_IFELSE(address@hidden)])
+AC_DEFUN([BAR], [
+foobar=
+AC_PROG_CC
+FOO
+])
+BAR
address@hidden example
+
address@hidden
+With older versions of Autoconf, the setting of @samp{foobar=} occurs
+before the single compiler check, as the author intended. But with
+Autoconf 2.64, this issues the ``expanded before it was required''
+warning for @code{AC_PROG_CC}, and outputs two copies of the compiler
+check, one before @samp{foobar=}, and one after. To understand why this
+is happening, remember that the use of @code{AC_COMPILE_IFELSE} includes
+a call to @code{AC_REQUIRE([AC_PROG_CC])} under the hood. According to
+the documented semantics of @code{AC_REQUIRE}, this means that
address@hidden @emph{must} occur before the body of the outermost
address@hidden, which in this case is @code{BAR}, thus preceeding the
+use of @samp{foobar=}. The older versions of Autoconf were broken with
+regards to the rules of @code{AC_REQUIRE}, which explains why the code
+changed from one over to two copies of @code{AC_PROG_CC} when upgrading
+autoconf. In other words, the author was unknowingly relying on a bug
+exploit to get the desired results, and that exploit broke once the bug
+was fixed.
+
+So, what recourse does the author have, to restore their intended
+semantics of setting @samp{foobar=} prior to a single compiler check,
+regardless of whether Autoconf 2.63 or 2.64 is used? One idea is to
+remember that only @code{AC_DEFUN} is impacted by @code{AC_REQUIRE};
+there is always the possibility of using the lower-level
address@hidden:
+
address@hidden
+AC_DEFUN([FOO], [AC_COMPILE_IFELSE(address@hidden)])
+m4_define([BAR], [
+foobar=
+AC_PROG_CC
+FOO
+])
+BAR
address@hidden example
+
address@hidden
+This works great if everything is in the same file. However, it does
+not help in the case where the author wants to have @command{aclocal}
+find the definition of @code{BAR} from its own file, since
address@hidden requires the use of @code{AC_DEFUN}. In this case, a
+better fix is to recognize that if @code{BAR} also uses
address@hidden, then there will no longer be direct expansion prior
+to a subsequent require. Then, by creating yet another helper macro,
+the author can once again guarantee a single invocation of
address@hidden, which will still occur after @code{foobar=}. The
+author can also use @code{AC_BEFORE} to make sure no other macro
+appearing before @code{BAR} has triggered an unwanted expansion of
address@hidden
+
address@hidden
+AC_DEFUN([FOO], [AC_COMPILE_IFELSE(address@hidden)])
+AC_DEFUN([BEFORE_CC], [
+foobar=
+])
+AC_DEFUN([BAR], [
+AC_BEFORE([$0], [AC_PROG_CC])dnl
+AC_REQUIRE([BEFORE_CC])dnl
+AC_REQUIRE([AC_PROG_CC])dnl
+FOO
+])
+BAR
address@hidden example
+
+
@c ===================================================== History of Autoconf.
@node History
diff --git a/lib/m4sugar/m4sh.m4 b/lib/m4sugar/m4sh.m4
index 2b32802..052c7eb 100644
--- a/lib/m4sugar/m4sh.m4
+++ b/lib/m4sugar/m4sh.m4
@@ -514,14 +514,16 @@ _AS_UNSET_PREPARE
# | esac
# The shell comments are intentional, to work around people who don't
# realize the impacts of using insufficient m4 quoting. This macro
-# always provides a default case, to work around a Solaris /bin/sh
-# bug regarding the exit status when no case matches.
+# always uses : and provides a default case, to work around Solaris
+# /bin/sh bugs regarding the exit status.
m4_define([_AS_CASE],
[ address@hidden:@(]
- $1[)] m4_default([$2], [:]) ;;])
+ $1[)] :
+ $2 ;;])
m4_define([_AS_CASE_DEFAULT],
[ address@hidden:@(]
- *[)] m4_default([$1], [:]) ;;])
+ *[)] :
+ $1 ;;])
m4_defun([AS_CASE],
[case $1 in[]m4_map_args_pair([_$0], [_$0_DEFAULT],
@@ -583,8 +585,8 @@ m4_defun([AS_FOR],
[m4_pushdef([$1], m4_if([$3], [], [[$$2]], m4_translit([$3], ]dnl
m4_dquote(_m4_defn([m4_cr_symbols2]))[[%+=:,./-]), [], [[$3]], [[$$2]]))]dnl
[for $2[]m4_ifval([$3], [ in $3])
-do
- m4_default([$4], [:])
+do :
+ $4
done[]_m4_popdef([$1])])
@@ -602,17 +604,18 @@ done[]_m4_popdef([$1])])
# with simplifications if IF-TRUE1 and/or IF-FALSE is empty.
#
m4_define([_AS_IF],
-[elif $1; then
- m4_default([$2], [:])
+[elif $1; then :
+ $2
])
m4_define([_AS_IF_ELSE],
-[m4_ifvaln([$1],
-[else
- $1])])
+[m4_ifnblank([$1],
+[else :
+ $1
+])])
m4_defun([AS_IF],
-[if $1; then
- m4_default([$2], [:])
+[if $1; then :
+ $2
m4_map_args_pair([_$0], [_$0_ELSE], m4_shift2($@))]dnl
[fi[]])# AS_IF
diff --git a/lib/m4sugar/m4sugar.m4 b/lib/m4sugar/m4sugar.m4
index 8356d08..420fd99 100644
--- a/lib/m4sugar/m4sugar.m4
+++ b/lib/m4sugar/m4sugar.m4
@@ -335,6 +335,29 @@ m4_builtin([sinclude], [$1])])
# it runs TRUE, etc.
+# m4_ifblank(COND, [IF-BLANK], [IF-TEXT])
+# m4_ifnblank(COND, [IF-TEXT], [IF-BLANK])
+# ----------------------------------------
+# If COND is empty, or consists only of blanks (space, tab, newline),
+# then expand IF-BLANK, otherwise expand IF-TEXT. This differs from
+# m4_ifval only if COND has just whitespace, but it helps optimize in
+# spite of users who mistakenly leave trailing space after what they
+# thought was an empty argument:
+# macro(
+# []
+# )
+#
+# Writing one macro in terms of the other causes extra overhead, so
+# we inline both definitions.
+m4_define([m4_ifblank],
+[m4_if(m4_translit([[$1]], [ ][ ][
+]), [], [$2], [$3])])
+
+m4_define([m4_ifnblank],
+[m4_if(m4_translit([[$1]], [ ][ ][
+]), [], [$3], [$2])])
+
+
# m4_ifval(COND, [IF-TRUE], [IF-FALSE])
# -------------------------------------
# If COND is not the empty string, expand IF-TRUE, otherwise IF-FALSE.
@@ -559,31 +582,43 @@ m4_define([m4_define_default],
# m4_default(EXP1, EXP2)
-# ----------------------
-# Returns EXP1 if non empty, otherwise EXP2. Expand the result.
+# m4_default_nblank(EXP1, EXP2)
+# -----------------------------
+# Returns EXP1 if not empty/blank, otherwise EXP2. Expand the result.
#
-# This macro is called on hot paths, so inline the contents of m4_ifval,
+# m4_default is called on hot paths, so inline the contents of m4_ifval,
# for one less round of expansion.
m4_define([m4_default],
[m4_if([$1], [], [$2], [$1])])
+m4_define([m4_default_nblank],
+[m4_ifblank([$1], [$2], [$1])])
+
# m4_default_quoted(EXP1, EXP2)
-# -----------------------------
-# Returns EXP1 if non empty, otherwise EXP2. Leave the result quoted.
+# m4_default_nblank_quoted(EXP1, EXP2)
+# ------------------------------------
+# Returns EXP1 if non empty/blank, otherwise EXP2. Leave the result quoted.
#
# For comparison:
# m4_define([active], [ACTIVE])
# m4_default([active], [default]) => ACTIVE
# m4_default([], [active]) => ACTIVE
+# -m4_default([ ], [active])- => - -
+# -m4_default_nblank([ ], [active])- => -ACTIVE-
# m4_default_quoted([active], [default]) => active
# m4_default_quoted([], [active]) => active
+# -m4_default_quoted([ ], [active])- => - -
+# -m4_default_nblank_quoted([ ], [active])- => -active-
#
-# This macro is called on hot paths, so inline the contents of m4_ifval,
+# m4_default macro is called on hot paths, so inline the contents of m4_ifval,
# for one less round of expansion.
m4_define([m4_default_quoted],
[m4_if([$1], [], [[$2]], [[$1]])])
+m4_define([m4_default_nblank_quoted],
+[m4_ifblank([$1], [[$2]], [[$1]])])
+
# m4_defn(NAME)
# -------------
diff --git a/tests/m4sh.at b/tests/m4sh.at
index d747bfe..5f7dc84 100644
--- a/tests/m4sh.at
+++ b/tests/m4sh.at
@@ -859,6 +859,11 @@ rm -f file
AS_CASE([`touch file; false`]) && test -f file && echo fifteen
dnl The next line is badly underquoted; don't intentionally copy this style.
AS_CASE([foo], [foo], m4_do(AS_CASE([bar], [bar], [echo sixteen])))
+dnl Handle blank arguments.
+AS_IF([false], [:], [ ]) && AS_CASE([foo], [foo], []
+) && echo seventeen
+m4_define([empty])AS_IF([false], [:], [empty]
+) && AS_CASE([foo], [foo], [empty]) && echo eighteen
# check that require works correctly
m4_for([n], 1, 9, [],
@@ -911,6 +916,8 @@ thirteen
fourteen
fifteen
sixteen
+seventeen
+eighteen
foo1=1 bar1=1
foo2=2 bar2=
foo3=3 bar3=
@@ -979,13 +986,15 @@ AS_FOR([m4var], [shvar], ['$list'],
AS_FOR([m4var], [shvar], [\'],
[echo "m4var $shvar"])
-# Syntax checks: cope with empty arguments.
+# Syntax checks: cope with empty/blank arguments.
set f g
AS_FOR([], [shvar], [],
[echo "m4_defn([]) $shvar"])
rm -f file
AS_FOR([], [shvar], [`touch file`])
test -f file || exit 1
+AS_FOR([], [shvar], [], [ ])
+m4_define([empty])AS_FOR([], [shvar], [], [empty])
# Check that break works.
while :
diff --git a/tests/m4sugar.at b/tests/m4sugar.at
index 6286af2..2dd81dc 100644
--- a/tests/m4sugar.at
+++ b/tests/m4sugar.at
@@ -649,6 +649,91 @@ m
AT_CLEANUP
+## ------------------------------------------------- ##
+## m4_ifval, m4_ifblank, m4_ifset, m4_default, etc. ##
+## ------------------------------------------------- ##
+
+AT_SETUP([m4sugar shorthand conditionals])
+AT_KEYWORDS([m4@&address@hidden m4@&address@hidden m4@&address@hidden
m4@&address@hidden
+m4@&address@hidden m4@&address@hidden m4@&address@hidden
+m4@&address@hidden)
+
+AT_CHECK_M4SUGAR_TEXT([[m4_define([active], [ACTIVE])m4_define([empty])
+m4_ifval([active], [yes], [no])
+m4_ifval([empty], [yes], [no])
+m4_ifval([ ], [yes], [no])
+m4_ifval([], [yes], [no])
+m4_ifblank([active], [yes], [no])
+m4_ifblank([empty], [yes], [no])
+m4_ifblank([ ], [yes], [no])
+m4_ifblank([], [yes], [no])
+m4_ifnblank([active], [yes], [no])
+m4_ifnblank([empty], [yes], [no])
+m4_ifnblank([ ], [yes], [no])
+m4_ifnblank([], [yes], [no])
+m4_ifset([active], [yes], [no])
+m4_ifset([empty], [yes], [no])
+m4_ifset([ ], [yes], [no])
+m4_ifset([], [yes], [no])
+---
+m4_define([demo1], [m4_default([$1], [$2])])dnl
+m4_define([demo2], [m4_default_quoted([$1], [$2])])dnl
+m4_define([demo3], [m4_default_nblank([$1], [$2])])dnl
+m4_define([demo4], [m4_default_nblank_quoted([$1], [$2])])dnl
+demo1([active], [default])
+demo1([], [active])
+demo1([empty], [text])
+-demo1([ ], [active])-
+demo2([active], [default])
+demo2([], [active])
+demo2([empty], [text])
+-demo2([ ], [active])-
+demo3([active], [default])
+demo3([], [active])
+demo3([empty], [text])
+-demo3([ ], [active])-
+demo4([active], [default])
+demo4([], [active])
+demo4([empty], [text])
+-demo4([ ], [active])-
+]], [[
+yes
+yes
+yes
+no
+no
+no
+yes
+yes
+yes
+yes
+no
+no
+yes
+no
+no
+no
+---
+ACTIVE
+ACTIVE
+
+- -
+active
+active
+empty
+- -
+ACTIVE
+ACTIVE
+
+-ACTIVE-
+active
+active
+empty
+-active-
+]])
+
+AT_CLEANUP
+
## --------- ##
## m4_cond. ##
## --------- ##
hooks/post-receive
--
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