Re: Regression with large XML data input

On 2025-12-25 08:29 +0100, zengman wrote:
> > The whitespace can be preserved by setting xmlKeepBlanksDefault before
> > parsing. See attached v2. That function is deprecated, though. But
> > libxml2 uses thread-local globals, so it should be safe. Other than
> > that, I see no other way to set XML_PARSE_NOBLANKS with
> > xmlParseBalancedChunkMemory.
> >
> > [1] https://gitlab.gnome.org/GNOME/libxml2/-/blob/408bd0e18e6ddba5d18e51d52da0f7b3ca1b4421/parserInternals.c#L2833
>
> Hi everyone,
>
> I have a small issue that needs resolving.
>
> My environment:
> ```
> postgres(at)zxm-VMware-Virtual-Platform:~$ uname -i -s -r -v
> Linux 6.11.0-29-generic #29-Ubuntu SMP PREEMPT_DYNAMIC Fri Jun 13 20:29:41 UTC 2025 x86_64
> postgres(at)zxm-VMware-Virtual-Platform:~$
> postgres(at)zxm-VMware-Virtual-Platform:~$ xml2-config --version
> 2.12.7
> ```
>
> After setting COPT=-Werror, compilation fails with the following errors (warnings are enforced as errors):
> ```
> xml.c: In function ‘xml_parse’:
> xml.c:1919:25: error: ‘xmlKeepBlanksDefault’ is deprecated [-Werror=deprecated-declarations]
> 1919 | save_keep_blanks = xmlKeepBlanksDefault(preserve_whitespace ? 1 : 0);
> | ^~~~~~~~~~~~~~~~
> In file included from xml.c:51:
> /usr/include/libxml2/libxml/parser.h:957:17: note: declared here
> 957 | xmlKeepBlanksDefault (int val);
> | ^~~~~~~~~~~~~~~~~~~~
> xml.c:1943:25: error: ‘xmlKeepBlanksDefault’ is deprecated [-Werror=deprecated-declarations]
> 1943 | xmlKeepBlanksDefault(save_keep_blanks);
> | ^~~~~~~~~~~~~~~~~~~~
> /usr/include/libxml2/libxml/parser.h:957:17: note: declared here
> 957 | xmlKeepBlanksDefault (int val);
> | ^~~~~~~~~~~~~~~~~~~~
> xml.c:1956:17: error: ‘xmlKeepBlanksDefault’ is deprecated [-Werror=deprecated-declarations]
> 1956 | xmlKeepBlanksDefault(save_keep_blanks);
> | ^~~~~~~~~~~~~~~~~~~~
> /usr/include/libxml2/libxml/parser.h:957:17: note: declared here
> 957 | xmlKeepBlanksDefault (int val);
> | ^~~~~~~~~~~~~~~~~~~~
> cc1: all warnings being treated as errors
> ```
>
> These deprecation warnings do not impact the test results in any way.
> Therefore, I have attached a patch to suppress these specific warnings.

The patch works when building with COPT=-Werror. I guess the change is
okay since we already make use of -Wno-deprecated-declarations in
src/backend/jit/llvm/Makefile:

# LLVM 14 produces deprecation warnings. We'll need to make some changes
# before the relevant functions are removed, but for now silence the warnings.
ifeq ($(GCC), yes)
LLVM_CFLAGS += -Wno-deprecated-declarations
endif

But do we need the same guard for GCC here as well?

Alternatively, can you upgrade to libxml2 2.13.3+ which undeprecated
xmlKeepBlanksDefault?

--
Erik Wienhold