Compilation error with MSYS2 CLANG{64,32} environments

[k-takata]

https://github.com/universal-ctags/ctags-win32/actions/runs/6924537331/job/18833909212
https://github.com/universal-ctags/ctags-win32/actions/runs/6924537331/job/18833909365

main/lxpath.c:166:3: error: call to undeclared function 'xmlLineNumbersDefault'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
  166 |                 xmlLineNumbersDefault (1);
      |                 ^
main/lxpath.c:167:9: error: call to undeclared function 'xmlParseMemory'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
  167 |                 doc = xmlParseMemory((const char*)data, size);
      |                       ^
main/lxpath.c:167:7: error: incompatible integer to pointer conversion assigning to 'xmlDocPtr' (aka 'struct _xmlDoc *') from 'int' [-Wint-conversion]
  167 |                 doc = xmlParseMemory((const char*)data, size);
      |                     ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3 errors generated.

It seems that xmlLineNumbersDefault and xmlParseMemory are deprecated.
https://gnome.pages.gitlab.gnome.org/libxml2/devhelp/libxml2-parser.html
(Not sure why these errors don't occur with MSYS2 MINGW{32,64} environments, though. Both use libxml2-2.12.0.)

[k-takata]

These error didn't occur when libxml2-2.11.6 was used:
https://github.com/universal-ctags/ctags-win32/actions/runs/6911068107/job/18805112817

[k-takata]

It seems that MINGW{32,64} have another errors with libxml2-2.12.0.

MINGW64:
https://github.com/universal-ctags/ctags-win32/actions/runs/6917682193/job/18819132209

	--- ./Tmain/selector-xml-root-elelement.d/stdout-expected.txt	2023-11-19 01:59:33.486877700 +0000
	+++ D:/a/ctags-win32/ctags-win32/ctags/Tmain/selector-xml-root-elelement.d/stdout-actual.txt	2023-11-19 02:05:51.950974900 +0000
	@@ -1 +0,0 @@
	-input.xml: DBusIntrospect

MINGW32:
https://github.com/universal-ctags/ctags-win32/actions/runs/6917682193/job/18819132302

	--- ./Units/parser-ant.r/xpath-based.d/expected.tags	2023-11-19 01:59:28.699355000 +0000
	+++ D:/a/ctags-win32/ctags-win32/ctags/Units/parser-ant.r/xpath-based.d/FILTERED.tmp	2023-11-19 02:06:00.988167700 +0000
	@@ -4,4 +4,4 @@
	-clean	input.xml	/^  <target name="clean" depends="init">$/;"	t	language:Ant	project:MyProject	roles:def
	-compile_something	input.xml	/^  <target name="compile_something" depends="init">$/;"	t	language:Ant	project:MyProject	roles:def
	-deploy	input.xml	/^    <target name="deploy" depends="compile_something, generate_h_from_java">$/;"	t	language:Ant	project:MyProject	roles:def
	-generate_h_from_java	input.xml	/^  <target name="generate_h_from_java" depends="compile_something">$/;"	t	language:Ant	project:MyProject	roles:def
	+clean	input.xml	/^$/;"	t	language:Ant	project:MyProject	roles:def
	+compile_something	input.xml	/^  <\/target>$/;"	t	language:Ant	project:MyProject	roles:def
	+deploy	input.xml	/^      link="http:\/\/java.sun.com\/j2se\/1.4.1\/docs\/api\/"$/;"	t	language:Ant	project:MyProject	roles:def
	+generate_h_from_java	input.xml	/^$/;"	t	language:Ant	project:MyProject	roles:def
	@@ -9 +9 @@
	-javadoc	input.xml	/^  <target name="javadoc">$/;"	t	language:Ant	project:MyProject	roles:def
	+javadoc	input.xml	/^  <\/target-->$/;"	t	language:Ant	project:MyProject	roles:def

[leleliu008]

lixml2-2.12.0 in MSYS2 was built with --with-legacy comfigure option, so it should be compatible with the older versions.

Reference: msys2/MSYS2-packages@d8c83a4

the real cause is that xmlLineNumbersDefault and xmlParseMemory functions are declared in libxml/parser.h, which in turn was not included in main/lxpath.c

diff --git a/main/lxpath.c b/main/lxpath.c
index 42e4a40e..275491a3 100644
--- a/main/lxpath.c
+++ b/main/lxpath.c
@@ -20,6 +20,7 @@
 #include "xtag.h"
 
 #ifdef HAVE_LIBXML
+#include <libxml/parser.h>
 #include <libxml/xpath.h>
 #include <libxml/tree.h>
 

[masatake]

@k-takata #3852 may fix this issue.
Could you try the latest master branch?
If the issue is still reproduced, please reopen this issue.

[k-takata]

I will check it in tomorrow's daily build.

[k-takata]

Unfortunately, still failing.
https://github.com/universal-ctags/ctags-win32/actions/runs/6951876383

[masatake]

@k-takata Thank you. I'll look into this.

[leleliu008]

libxml/parser.h should be included in main/selectors.c too.

[masatake]

In my understanding, @leleliu008 fixed the issue about the building.
The rest issue is about the test failures.

We must catch up on the newer API of libxml2. I'll work on this topic.

[k-takata]

Now the build error has been fixed.
However, as you expected, it is still failing.
https://github.com/universal-ctags/ctags-win32/actions/runs/6964711106

[masatake]

@k-takata Thank you. I'll work on fixing the failure at #3858.
Looks mysterious.

[masatake]

The error was reproduced with libxml2-2.12.1 + fedora:latest container.

[root@3baa1bab8976 ctags]# LD_LIBRARY_PATH=/usr/local/lib  ./ctags -o - --fields=+n Units/parser-ant.r/xpath-based.d/input.xml  | ./readtags -et - javadoc
javadoc Units/parser-ant.r/xpath-based.d/input.xml      /^  <\/target-->$/;"    kind:t  project:MyProject
[root@3baa1bab8976 ctags]# LD_LIBRARY_PATH= ./ctags -o - --fields=+n Units/parser-ant.r/xpath-based.d/input.xml  | ./readtags -et - javadoc
javadoc Units/parser-ant.r/xpath-based.d/input.xml      /^  <target name="javadoc">$/;" kind:t  project:MyProject

libxml2-2.10.4 is installed as a package in 'fedora:latest' container.

[masatake]

Git-bisect reported the following commit of libxml2 causes this issue:

[root@3baa1bab8976 libxml2]# git bisect good                                                                                                                                
cb927e851959219da1fec49d1cf088aac5579949 is the first bad commit                                                                                                            
commit cb927e851959219da1fec49d1cf088aac5579949                                       
Author: Nick Wellnhofer <wellnhofer@aevum.de>
Date:   Mon Sep 25 14:35:43 2023 +0200

    parser: Don't skip CR in xmlCurrentChar 
     
    Skip over carriage returns later in xmlNextChar.

 parserInternals.c | 34 +++++++++++++++++++++++++---------
 1 file changed, 25 insertions(+), 9 deletions(-)

https://gitlab.gnome.org/GNOME/libxml2/-/commit/cb927e851959219da1fec49d1cf088aac5579949

[masatake]

The commit cb927e851959219da1fec49d1cf088aac5579949 is small, but many commits have been added after the commit. So, I could not fix the bug in HEAD.

I reported the issue to https://gitlab.gnome.org/GNOME/libxml2/-/issues/628 with minimum reproducer. If I could fix the bug, we would have to add code to ctags not to use a broken version of libxml2.

On the platform using configure for building ctags, AC_TRY_RUN with the minimum reproducer in configure can be used to decide whether we should link libxml-2.0 to ctags or not.

[masatake]

It seems that the bug is fixed in https://gitlab.gnome.org/GNOME/libxml2/-/commit/43b511fa714df875dc4f40d108061eede0d4d76b.

(Added) I verified that the test case is passed with the libxml2 with the commit.

[masatake]

Close via #3858.

As I reported, a bug in libxml2 caused the failure of the test case.
It was fixed in the upstream project.

I added code detecting the bug of libxml2 to configure.ac. The code doesn't link libxml2 to ctags if the code detects the bug.