From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 13 Nov 2007 08:16:19 +0000 (-0800)
Subject: Don't worry about preprocessor when testing long long.
X-Git-Tag: v2.62~139
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9b0314cc939e888257727f152a700eea86c15a24;p=thirdparty%2Fautoconf.git

Don't worry about preprocessor when testing long long.

See: http://lists.gnu.org/archive/html/bug-gnulib/2007-11/msg00075.html
* doc/autoconf.texi (Preprocessor Arithmetic): New section.
(AC_TYPE_LONG_LONG_INT, AC_TYPE_UNSIGNED_LONG_LONG_INT):
These no longer check for preprocessor flaws.
* lib/autoconf/types.m4 (_AC_TYPE_LONG_LONG_SNIPPET):
Do not check for preprocessor flows.
---

diff --git a/ChangeLog b/ChangeLog
index cc23b5a9..79c6cc19 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2007-11-13  Paul Eggert  <eggert@cs.ucla.edu>
+
+	Don't worry about preprocessor when testing long long.
+	See: http://lists.gnu.org/archive/html/bug-gnulib/2007-11/msg00075.html
+	* doc/autoconf.texi (Preprocessor Arithmetic): New section.
+	(AC_TYPE_LONG_LONG_INT, AC_TYPE_UNSIGNED_LONG_LONG_INT):
+	These no longer check for preprocessor flaws.
+	* lib/autoconf/types.m4 (_AC_TYPE_LONG_LONG_SNIPPET):
+	Do not check for preprocessor flows.
+
 2007-11-13  Jim Meyering  <meyering@redhat.com>
 
 	Adapt dependencies, now that a version change doesn't modify configure.ac
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 8633fa2c..12eef55f 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -518,6 +518,7 @@ Portable C and C++ Programming
 
 * Varieties of Unportability::  How to make your programs unportable
 * Integer Overflow::            When integers get too large
+* Preprocessor Arithmetic::     @code{#if} expression problems
 * Null Pointers::               Properties of null pointers
 * Buffer Overruns::             Subscript errors and the like
 * Volatile Objects::            @code{volatile} and signals
@@ -6123,8 +6124,10 @@ range or precision than the @code{double} type, define
 @acindex{TYPE_LONG_LONG_INT}
 @cvindex HAVE_LONG_LONG_INT
 If the C compiler supports a working @code{long long int} type, define
-@code{HAVE_LONG_LONG_INT}.  This test also validates that the
-preprocessor can handle integers with the @samp{LL} suffix.
+@code{HAVE_LONG_LONG_INT}.  However, this test does not test
+@code{long long int} values in preprocessor @code{#if} expressions,
+because too many compilers mishandle such expressions.
+@xref{Preprocessor Arithmetic}.
 @end defmac
 
 @defmac AC_TYPE_MBSTATE_T
@@ -6261,12 +6264,10 @@ exists.
 @acindex{TYPE_UNSIGNED_LONG_LONG_INT}
 @cvindex HAVE_UNSIGNED_LONG_LONG_INT
 If the C compiler supports a working @code{unsigned long long int} type,
-define @code{HAVE_UNSIGNED_LONG_LONG_INT}.  This test also validates
-that the preprocessor can handle integers with the @samp{ULL} suffix.
-However, portable code cannot mix @code{unsigned long int} and
-@code{unsigned long long int} types in preprocessor expressions,
-since the @acronym{HP-UX} 11.00 preprocessor does not use consistent
-promotion rules.
+define @code{HAVE_UNSIGNED_LONG_LONG_INT}.  However, this test does not test
+@code{unsigned long long int} values in preprocessor @code{#if} expressions,
+because too many compilers mishandle such expressions.
+@xref{Preprocessor Arithmetic}.
 @end defmac
 
 @node Generic Types
@@ -16291,6 +16292,7 @@ more information.
 @menu
 * Varieties of Unportability::  How to make your programs unportable
 * Integer Overflow::            When integers get too large
+* Preprocessor Arithmetic::     @code{#if} expression problems
 * Null Pointers::               Properties of null pointers
 * Buffer Overruns::             Subscript errors and the like
 * Volatile Objects::            @code{volatile} and signals
@@ -16656,6 +16658,20 @@ of these two values typically yields the same signal on these CPUs,
 even though the C standard requires @code{INT_MIN % -1} to yield zero
 because the expression does not overflow.
 
+@node Preprocessor Arithmetic
+@section Preprocessor Arithmetic
+@cindex preprocessor arithmetic
+
+In C99, preprocessor arithmetic, used for @code{#if} expressions, must
+be evaluated as if all signed values are of type @code{intmax_t} and all
+unsigned values of type @code{uintmax_t}.  Many compilers are buggy in
+this area, though.  For example, as of 2007, Sun C mishandles @code{#if
+LLONG_MIN < 0} on a platform with 32-bit @code{long int} and 64-bit
+@code{long long int}.  Also, some older preprocessors mishandle
+constants ending in @code{LL}.  To work around these problems, you can
+compute the value of expressions like @code{LONG_MAX < LLONG_MAX} at
+@code{configure}-time rather than at @code{#if}-time.
+
 @node Null Pointers
 @section Properties of Null Pointers
 @cindex null pointers
diff --git a/lib/autoconf/types.m4 b/lib/autoconf/types.m4
index 9c38a7bb..6f037380 100644
--- a/lib/autoconf/types.m4
+++ b/lib/autoconf/types.m4
@@ -475,14 +475,7 @@ You should use `AC_TYPE_LONG_DOUBLE' or `AC_TYPE_LONG_DOUBLE_WIDER' instead.]
 AC_DEFUN([_AC_TYPE_LONG_LONG_SNIPPET],
 [
   AC_LANG_PROGRAM(
-    [[/* Test preprocessor.  */
-      #if ! (-9223372036854775807LL < 0 && 0 < 9223372036854775807ll)
-        error in preprocessor;
-      #endif
-      #if ! (18446744073709551615ULL <= -1ull)
-        error in preprocessor;
-      #endif
-      /* Test literals.  */
+    [[/* Test literals.  */
       long long int ll = 9223372036854775807ll;
       long long int nll = -9223372036854775807LL;
       unsigned long long int ull = 18446744073709551615ULL;