From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sun, 24 May 2020 02:06:16 +0000 (-0700)
Subject: assure: new macro ‘affirm’
X-Git-Tag: v1.0~4074
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=f58691b91ed22372b4a962432aa3ea860fe1cbbb;p=thirdparty%2Fgnulib.git

assure: new macro ‘affirm’

* lib/assure.h: Include verify.h.
(affirm): New macro, after a suggestion by Marc Nieper-Wißkirchen in:
https://lists.gnu.org/r/bug-gnulib/2020-05/msg00263.html
and commentary by Bruno Haible in:
https://lists.gnu.org/r/bug-gnulib/2020-05/msg00278.html
* modules/assure (Depends-on:): Add verify.
---

diff --git a/ChangeLog b/ChangeLog
index a7101db80f..c05ef910dc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2020-05-23  Paul Eggert  <eggert@cs.ucla.edu>
+
+	assure: new macro ‘affirm’
+	* lib/assure.h: Include verify.h.
+	(affirm): New macro, after a suggestion by Marc Nieper-Wißkirchen in:
+	https://lists.gnu.org/r/bug-gnulib/2020-05/msg00263.html
+	and commentary by Bruno Haible in:
+	https://lists.gnu.org/r/bug-gnulib/2020-05/msg00278.html
+	* modules/assure (Depends-on:): Add verify.
+
 2020-05-23  Bruno Haible  <bruno@clisp.org>
 
 	calloc-gnu: Make test work in non-flat address spaces.
diff --git a/lib/assure.h b/lib/assure.h
index 8ea2f6e480..09a4edfa59 100644
--- a/lib/assure.h
+++ b/lib/assure.h
@@ -21,12 +21,32 @@
 #define _GL_ASSURE_H
 
 #include <assert.h>
+#include "verify.h"
+
+/* Evaluate an assertion E that is guaranteed to be true.
+   If NDEBUG is not defined, abort the program if E is false.
+   If NDEBUG is defined, the compiler can assume E and behavior is
+   undefined if E is false, fails to evaluate, or has side effects.
+
+   Unlike standard 'assert', this macro evaluates E even when NDEBUG
+   is defined, so as to catch typos, avoid some GCC warnings, and
+   improve performance when E is simple enough.
+
+   Also see the documentation for 'assume' in verify.h.  */
+
+#ifdef NDEBUG
+# define affirm(E) assume (E)
+#else
+# define affirm(E) assert (E)
+#endif
 
 /* Check E's value at runtime, and report an error and abort if not.
    However, do nothing if NDEBUG is defined.
 
-   Unlike standard 'assert', this macro always compiles E even when NDEBUG
-   is defined, so as to catch typos and avoid some GCC warnings.  */
+   Unlike standard 'assert', this macro compiles E even when NDEBUG
+   is defined, so as to catch typos and avoid some GCC warnings.
+   Unlike 'affirm', it is OK for E to use hard-to-optimize features,
+   since E is not executed if NDEBUG is defined.  */
 
 #ifdef NDEBUG
 # define assure(E) ((void) (0 && (E)))
diff --git a/modules/assure b/modules/assure
index 3cfe1f874e..c37191717c 100644
--- a/modules/assure
+++ b/modules/assure
@@ -5,6 +5,7 @@ Files:
 lib/assure.h
 
 Depends-on:
+verify
 
 configure.ac: