[only 8.5 rc2] `make -j32` or `make -j4` fail, `make -j` works (missing zend_language_scanner_defs.h)

[henderkes]

Description

The following code:

// untar 8.5.0 rc2, cd into folder
// extract ast extension source into ext/ast
./configure --disable-all --enable-cli --enable-ast
make -j32

Resulted in this output:

/bin/sh /home/m/static-php-cli/source/php-src/libtool --silent --preserve-dup-deps --tag=CC --mode=compile gcc -Iext/json/ -I/home/m/static-php-cli/source/php-src/ext/json/ -I/home/m/static-php-cli/source/php-src/main -I/home/m/static-php-cli/source/php-src -I/home/m/static-php-cli/source/php-src/ext/date/lib -I/home/m/static-php-cli/source/php-src/ext/lexbor -I/home/m/static-php-cli/source/php-src/ext/uri/uriparser/include -I/home/m/static-php-cli/source/php-src/TSRM -I/home/m/static-php-cli/source/php-src/Zend  -I/home/m/static-php-cli/buildroot/include -D_GNU_SOURCE -D_REENTRANT -pthread  -fno-common -Wstrict-prototypes -Wformat-truncation -Wlogical-op -Wduplicated-cond -Wno-clobbered -Wall -Wextra -Wno-unused-parameter -Wno-sign-compare -fPIC -Os -fPIE -ffp-contract=off -fvisibility=hidden -pthread -DNDEBUG -DZTS -Wimplicit-fallthrough=1 -DZEND_MAX_EXECUTION_TIMERS  -g -fstack-protector-strong -fno-ident -fPIE -fPIC -Os -DZEND_ENABLE_STATIC_TSRMLS_CACHE=1 -c /home/m/static-php-cli/source/php-src/ext/json/json_encoder.c -o ext/json/json_encoder.lo  -MMD -MF ext/json/json_encoder.dep -MT ext/json/json_encoder.lo
/home/m/static-php-cli/source/php-src/ext/ast/ast.c:12:10: fatal error: zend_language_scanner_defs.h: No such file or directory
   12 | #include "zend_language_scanner_defs.h"
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
make: *** [Makefile:530: ext/ast/ast.lo] Error 1
make: *** Waiting for unfinished jobs....

But I expected this output instead:

Build complete.
Don't forget to run 'make test'.

I could imagine that this is only an issue because the ast extension doesn't declare all of it's dependencies as it's expected to be compiled as a shared extension, but I still find it very curious that this always works with other php versions and it always works with make -j instead of make -j32 or even make -j1.

PHP Version

PHP 8.5.0 RC2.
8.2, 8.3, 8.4 and 8.5 beta1-3 work.

Operating System

x86_64-linux and aarch64-linux

[henderkes]

Actually, removing the ast extension, other extensions face similar issues. Something may have changed in the php build system that previously made Zend targets run first?

[iluuu1994]

Did you run make distclean and try a full rebuild? Potentialyl also ccache -C. Can you check whether the file is actually there?

[henderkes]

Yes, completely removing the directory before each rebuild.
The file does not exist. It appears that it tries to build things in the wrong order. We do not use ccache.

After using make -j instead of make -j32 the compilation succeeds and then looking for the file shows it:

[m@M php-src]$ find ./ -name "zend_language_scanner_defs.h"
./Zend/zend_language_scanner_defs.h

Perhaps useful extra information: this happens on all operating systems and machines I'm building on, namely:
AlmaLinux 7-10, Ubuntu 24.04 and Debian 11.
Locally (-j32) and in GitHub runners (-j4).

[iluuu1994]

I believe this is caused by a missing dependency declaration then. Consider tokenizer.c in php-src, which also includes zend_language_scanner_defs.h. It explicitly declares zend_language_scanner.c as a dependency, which will in turn generate zend_language_scanner_defs.h.

php-src/ext/tokenizer/Makefile.frag

Line 5 in b3d8465

$(builddir)/tokenizer.lo: $(top_srcdir)/Zend/zend_language_parser.c $(top_srcdir)/Zend/zend_language_scanner.c

This doesn't happen when you build php-ast out-of-tree, which is how it's usually built, because there these headers were already generated. So, I'm not sure this is supposed to work. But I also don't understand how this would be a PHP 8.5 only issue. Maybe some other dependency previously would implicitly cause it to be delayed.

[henderkes]

Likewise, I don't know why it's only an issue for RC2. I missed RC1 and haven't tested with it yet, but beta 1-3 built just fine.

I'm just wondering, given that is always works with make -j and always fails with make -jN, perhaps there's something in the php build system that changed in regards to parallelisation?

[iluuu1994]

Regardless of why it worked accidentally, php-ast would need to update their build config to conditionally add a fragment file to add zend_language_scanner.c as a dependency, depending on whether it's being build in or out-of-free. I'm not very well-versed with the build system, maybe @petk knows whether that's possible. Peter can also correct me if my understanding is wrong. But I don't think this is a php-src issue.

[petk]

Bison generates the header file (zend_language_scanner_defs.h) with slight delay sometimes and dependency on this file should be added somewhere also probably or perhaps on the entire bison step. Yes, this happens on larger number of CPUs here and there. I'm not sure how to fix it with Makefiles only. For the ast extension this issue can be resolved for 99% cases by adding a dependency similar to ext/tokenizer, I think. Otherwise, this still can happen here and there but with very small reproducibility.

In my CMake-based build, this is otherwise also "resolved" https://github.com/petk/php-build-system/blob/master/docs/cmake/differences.md#bugs-fixed :D I've encountered it also.

[iluuu1994]

@petk Btw, is it planned to propose to add official support for CMake at some point? Would be a shame if all that work goes to waste.

[henderkes]

Yes, this happens on larger number of CPUs here and there.

For reference, this happens with any -jN where N is a positive number, with 100% reproducibility in php 8.5 RC2 and it never happens with 8.2-8.4 release / 8.5 beta3. I don't understand how the php build system could have changed something related to it, but I also don't believe in that much of a coincidence.

My actions all fail, every day, to the same error on the php 8.5 build since switching to rc2: https://github.com/static-php/spc-packages/actions/runs/18734033401

[henderkes]

Just updated to RC3 and it isn't happening anymore.

[iluuu1994]

I don't see any relevant changes between the two RCs. php-8.5.0RC2...php-8.5.0RC3 So, there's most likely some unpredictable component involved. Properly declaring depencencies should be the solution, though again I don't know how well this is possible for an external extension that isn't meant to be built in-tree.

[henderkes]

Yeah, I don't see anything relevant either. Introducing the check would be possible, but the ast extension isn't exactly the most active at the moment. I'll create a PR soon.