From: Willy Tarreau <w@1wt.eu>
Date: Fri, 7 Apr 2023 12:34:38 +0000 (+0200)
Subject: BUILD: compiler: fix __equals_1() on older compilers
X-Git-Tag: v2.8-dev7~4
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=988e19c60715f8f19a9ecee8fbf647bf9d846c95;p=thirdparty%2Fhaproxy.git

BUILD: compiler: fix __equals_1() on older compilers

It appeared that __has_attribute() doesn't work on gcc 4.4 and older
because the concatenation of __has_attribute##x isn't resolved as a one
before being passed to __equals_1() which immediately concatenates it to
comma_for_one. We first need to pass it through an extra layer to resolve
this name to a value. The new version was tested with gcc 4.2 to 11.3.

This may be backported though it's pretty minor.
---

diff --git a/include/haproxy/compiler.h b/include/haproxy/compiler.h
index 5b9c668bb4..3e00493768 100644
--- a/include/haproxy/compiler.h
+++ b/include/haproxy/compiler.h
@@ -50,9 +50,10 @@
  * second one.
  */
 #define comma_for_one1 ,
-#define ____equals_1(x, y, ...) (y)
-#define ___equals_1(x, ...) ____equals_1(x, 0)
-#define __equals_1(x) ___equals_1(comma_for_one ## x 1)
+#define _____equals_1(x, y, ...) (y)
+#define ____equals_1(x, ...) _____equals_1(x, 0)
+#define ___equals_1(x)       ____equals_1(comma_for_one ## x 1)
+#define __equals_1(x)        ___equals_1(x)
 
 /* gcc 5 and clang 3 brought __has_attribute(), which is not well documented in
  * the case of gcc, but is convenient since handled at the preprocessor level.