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[PATCH] docs: improve the prose describing _AC_CHECK_TYPE_NEW_BODY


From: Jim Meyering
Subject: [PATCH] docs: improve the prose describing _AC_CHECK_TYPE_NEW_BODY
Date: Thu, 01 Sep 2011 20:36:48 +0200

FYI,
While looking at a config.log file, I noticed a diagnostic that was due
to the code below, and found it suspicious enough that I went to read the
macro definition.

>From 7a615729c9c56a3608ec0224a67f21d23ea6b3ad Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Sun, 24 Jul 2011 15:50:36 +0200
Subject: [PATCH] docs: improve the prose describing _AC_CHECK_TYPE_NEW_BODY

* lib/autoconf/types.m4 (_AC_CHECK_TYPE_NEW_BODY): Improve prose.
---
 ChangeLog             |    5 +++++
 lib/autoconf/types.m4 |   16 +++++++++-------
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 1e17e60..219176f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2011-07-24  Jim Meyering  <address@hidden>
+
+       docs: improve the prose describing _AC_CHECK_TYPE_NEW_BODY
+       * lib/autoconf/types.m4 (_AC_CHECK_TYPE_NEW_BODY): Improve prose.
+
 2011-08-31  Paul Eggert  <address@hidden>

        AC_C_CONST: don't reject gcc -Werror -Wall
diff --git a/lib/autoconf/types.m4 b/lib/autoconf/types.m4
index c47884c..72093e9 100644
--- a/lib/autoconf/types.m4
+++ b/lib/autoconf/types.m4
@@ -80,15 +80,15 @@
 #        int foo (TYPE param);
 #
 # but of course you soon realize this does not make it with K&R
-# compilers.  And by no ways you want to
+# compilers.  And by no means do you want to use this:
 #
 #        int foo (param)
 #          TYPE param
 #        { ; }
 #
-# since this time it's C++ who is not happy.
+# since C++ would complain loudly.
 #
-# Don't even think of the return type of a function, since K&R cries
+# Don't even think of using a function return type, since K&R cries
 # there too.  So you start thinking of declaring a *pointer* to this TYPE:
 #
 #        TYPE *p;
@@ -101,14 +101,16 @@
 #
 #        sizeof (TYPE);
 #
-# But this succeeds if TYPE is a variable: you get the size of the
-# variable's type!!!
+# That is great, but has one drawback: it succeeds when TYPE happens
+# to be a variable: you'd get the size of the variable's type.
+# Obviously, we must not accept a variable in place of a type name.
 #
-# So, to filter out the last possibility, you try this too:
+# So, to filter out the last possibility, we will require that this fail:
 #
 #        sizeof ((TYPE));
 #
-# This fails if TYPE is a type, but succeeds if TYPE is actually a variable.
+# This evokes a syntax error when TYPE is a type, but succeeds if TYPE
+# is actually a variable.
 #
 # Also note that we use
 #
--
1.7.7.rc0.362.g5a14



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