From 819c2d6423b4e0f55c5f69e334bf81570e82f68f Mon Sep 17 00:00:00 2001
From: "Ivan A. Melnikov" <iv@altlinux.org>
Date: Thu, 17 Aug 2023 14:15:03 +0400
Subject: [PATCH] Fix ABI detection for empty 'os.platform'

`in` operator in bjam always returns true if its first
argument has no elements[1]. This means that if `os.platform`
is empty (not detected), the construction introduced
in commit d039c8e4da79dbc76481236249e22892bfdde047 sets
ABI to `aapcs` on all platforms where `os.platform` is
empty, including, e.g. riscv64, and breaks build there.

This commit refactors the condition to use '=' operator,
to make sure that when `os.platform` is empty we get
the default ABI value, and thus fixes build on riscv64.

[1] https://www.boost.org/doc/libs/1_83_0/tools/build/doc/html/index.html#jam.language.flow_of_control

Fixes: d039c8e4da79dbc76481236249e22892bfdde047
---
 build/Jamfile.v2 | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/build/Jamfile.v2 b/build/Jamfile.v2
index faaf892..c07847a 100644
--- a/build/Jamfile.v2
+++ b/build/Jamfile.v2
@@ -79,7 +79,8 @@ local rule default_abi ( )
     local tmp = sysv ;
     if [ os.name ] = "NT" { tmp = ms ; }
     else if [ os.name ] = "CYGWIN" { tmp = ms ; }
-    else if [ os.platform ] in ARM ARM64 { tmp = aapcs ; }
+    else if [ os.platform ] = "ARM" { tmp = aapcs ; }
+    else if [ os.platform ] = "ARM64" { tmp = aapcs ; }
     else if [ os.platform ] = "MIPS32" { tmp = o32 ; }
     else if [ os.platform ] = "MIPS64" { tmp = n64 ; }
     return $(tmp) ;