From d388bd62f43b53d32622c57332ccf002e2ad7d67 Mon Sep 17 00:00:00 2001
From: Olly Betts <olly@survex.com>
Date: Wed, 14 Sep 2022 15:41:07 +1200
Subject: [PATCH] Stop trying to check for incompatible GCC ABI

These checks were helpful in the GCC 3 days, but ABI versions 2 and up
are compatible aside from obscure corner cases, and GCC now defaults to
using the latest ABI version it supports.  The result is that this check
is no longer useful enough to justify the noise.

We still check for incompatible _GLIBCXX_DEBUG between the library and
application builds, since that will cause things not to work, and the
error message doesn't make it clear what's wrong.

(cherry picked from commit e31ee8bf34f0b6332fc5559093982132ef5b4280)
---
 xapian-core/include/xapian/version_h.cc | 55 ++++-----------------------------
 1 file changed, 6 insertions(+), 49 deletions(-)

diff --git a/xapian-core/include/xapian/version_h.cc b/xapian-core/include/xapian/version_h.cc
index cad300c61..b36ae4df2 100644
--- a/xapian-core/include/xapian/version_h.cc
+++ b/xapian-core/include/xapian/version_h.cc
@@ -8,7 +8,7 @@ const char * dummy[] = {
 "/** @file",
 " * @brief Define preprocessor symbols for the library version",
 " */",
-"// Copyright (C) 2002,2004,2005,2006,2007,2008,2009,2010,2011,2012,2013,2015,2016,2017,2018,2020 Olly Betts",
+"// Copyright (C) 2002-2022 Olly Betts",
 "//",
 "// This program is free software; you can redistribute it and/or",
 "// modify it under the terms of the GNU General Public License as",
@@ -34,15 +34,12 @@ const char * dummy[] = {
 //"#endif",
 //"",
 #ifdef __GNUC__
-// When building the library with GCC, generate preprocessor code to check that
-// any version of GCC used to build applications has a matching C++ ABI. This
-// means that users get a nice explanatory error message rather than a
-// confusing link failure (or worse a program which builds but crashes).
-// Another benefit is that the check happens near the start of compilation of
-// the first source file which uses Xapian in the user's application, rather
-// than during the first attempt to link with Xapian.
+// We used to check __GXX_ABI_VERSION here which was helpful in the GCC 3 days,
+// but ABI versions 2 and up are compatible aside from obscure corner cases,
+// and GCC now defaults to using the latest ABI version it supports.  The
+// result is that this check was no longer useful enough to justify the noise.
 //
-// We also check that the setting of _GLIBCXX_DEBUG matches since that
+// We still check that the setting of _GLIBCXX_DEBUG matches since that
 // introduces ABI-like incompatibilities.
 //
 // After preprocessing with "g++ -E" or similar (which will expand macros,
@@ -54,50 +51,10 @@ const char * dummy[] = {
 //
 // So for lines we want in the output, we quote parts of the line which we
 // don't want substituting, and use @@ where we really want " in the output.
-#if defined __clang__
-# define BUILD_COMPILER "clang++ " __clang_version__
-#elif defined __INTEL_COMPILER
-# define BUILD_COMPILER "icc " J(__INTEL_COMPILER)
-# define J(A) #A
-#elif defined __GNUC_PATCHLEVEL__
-# define BUILD_COMPILER "g++ " V(__GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__)
-# define V(A,B,C) J(A,B,C)
-# define J(A,B,C) #A"."#B"."#C
-#else
-# define BUILD_COMPILER "g++ " V(__GNUC__, __GNUC_MINOR__)
-# define V(A,B) J(A,B)
-# define J(A,B) #A"."#B
-#endif
 "#ifdef __GNUC__",
 "#if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ == 0)",
 "#error Xapian no longer supports GCC < 3.1",
 "#else",
-#ifndef __GXX_ABI_VERSION
-#error GCC does not have __GXX_ABI_VERSION defined
-#endif
-// GCC 3.1 reports ABI version 100 (same as 3.0), but this should actually have
-// been 101!  But we reject 3.0 above, so this doesn't actually matter.
-"#if !defined(__GXX_ABI_VERSION) || __GXX_ABI_VERSION != ", __GXX_ABI_VERSION,
-#if __GXX_ABI_VERSION >= 1002
-// ABI versions 2 and up are compatible aside from obscure corner cases, so
-// issue a warning, but don't refuse to compile as there's a good chance that
-// things will actually work.
-"#if defined __GXX_ABI_VERSION && __GXX_ABI_VERSION >= 1002",
-"#warning The C++ ABI version of compiler you are using does not exactly match",
-"#warning that of the compiler used to build the library.  If linking fails",
-"#warning due to missing symbols, this is probably the reason why.",
-"#warning The Xapian library was built with ", BUILD_COMPILER
-"#else",
-#endif
-"#error The C++ ABI version of compiler you are using does not match",
-"#error that of the compiler used to build the library.  The versions",
-"#error must match or your program will not work correctly.",
-"#error The Xapian library was built with ", BUILD_COMPILER
-#if __GXX_ABI_VERSION >= 1002
-"#endif",
-#endif
-"#endif",
-"",
 // _GLIBCXX_DEBUG is supported by GCC 3.4 and later so we only need to check
 // it for those versions.
 #if (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4
-- 
2.11.4.GIT