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Language: generator with never return type and yield — compile-time fatal missing (zend_compile.c) #7351
Description
Category
language · php-src-strict
Problem
A function that yields cannot declare return type never. Zend rejects this at compile time:
Generator return type must be a supertype of Generator, never given
This compiler accepts the function (php bin/vm.php exits 0), so invalid generator signatures compile and can reach JIT/AOT.
php-src reference
- php/php-src
Zend/zend_compile.c— generator return type validation (neveris not a supertype ofGenerator)
Repro
Committed: test/repro-maintainer/parity_never_generator_yield.php
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php -l test/repro-maintainer/parity_never_generator_yield.php
php bin/vm.php test/repro-maintainer/parity_never_generator_yield.php; echo vm_exit=$?'| Runtime | Result |
|---|---|
| Zend PHP | Compile fatal: Generator return type must be a supertype of Generator, never given |
| bin/vm.php | Compiles and runs (exit 0) — gap |
Scope (PHP-in-PHP first)
| Path | Work |
|---|---|
lib/Compiler.php / generator lowering |
Reject never return on functions containing yield/yield from with Zend message |
| Tests | test/compliance/cases/language/never_generator_compile.phpt |
Done when
- Repro fails at compile time on VM with Zend message
- Ordinary
neverfunctions withoutyieldstill compile -
./script/ci-fast.sh --filter never_generator_compilegreen on VM
Activity
PurHur commentedon Jun 7, 2026
claim: worker-lane-b — starting this run
Reject :never return type on generator functions at compile time (#7351…
PurHur commentedon Jun 7, 2026
Merged via #7357.
Fix:
GeneratorNeverReturnCompileCheckrejects functions withyield/yield fromand return typeneverat compile time with Zend message: `Generator return type must be a supertype of Generator, never given`.Verification: