Create new OP_MULTIPARAM to implement subroutine signatures
#23574
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The previous names were just copied from similar fields in previous signature handling code. These new names are a better fit for their current and intended future purpose.
By defining a helper term for optional defaulting expression we can remove one of the three alternate cases down to just two. This will help when adding more code to these action blocks in future,
This two new helper functions will be useful for sharing behaviour with upcoming code, when adding OP_MULTIPARAM.
…gument processing The specific behaviour of this obscure modification case is not documented or relied upon elsewhere in code. Rather than attempt to preserve this cornercase, it's easier just to no longer test for it, as upcoming changes will alter the values that are visible.
Creates a new UNOP_AUX op type, `OP_MULTIPARAM`, that handles all of the
initial behaviour of assigning values to parameters of a subroutine
signature out of values passed by the caller. This is created in a
similar style to other multi-ops like `OP_MULTIDEREF` and
`OP_MULTICONCAT` where the op's aux structure contains a sub-program of
sorts, which describes all of the small details of operation.
Also adds a LOGOP, `OP_PARAMTEST` and UNOP `OP_PARAMSTORE` which are
responsible for implementing the default expressions of optional
parameters. These use the `SvPADSTALE` flag set on pad lexicals used as
parameters to remember whether assignment has happened, ensuring that
missing vs present-but-undef can be detected in a way that does not
depend on counting arguments on the stack.
This change is carefully designed to support two future ideas:
* Named parameters as per PPC0024
https://github.com/Perl/PPCs/blob/main/ppcs/ppc0024-signature-named-parameters.md
* "no-snails"; the performance optimisation that avoids storing
incoming argument values in the `@_` AV and instead consumes them
directly from the stack
|
Weirdly, while github CI and most commentors on IRC report test failures in In case it's somehow related to build options, the script I use to configure and build is: test -f config.sh && rm config.sh
test -f Policy.sh && rm Policy.sh
./Configure -des \
-Dusedevel \
-Dprefix=$HOME/perl5/perlbrew/perls/bleadperl/ \
-DDEBUGGING \
-Uversiononly \
-Dman1dir=none -Dman3dir=none \
-Dusethreads \
-Dinc_version_list=none \
-Doptimize='-gdwarf-2 -g3' \
"$@"
make -j8
make -j8 test_prep |
mauke
reviewed
Aug 15, 2025
| */ | ||
| varop->op_next = defop; | ||
| defexpr->op_next = varop; | ||
| param->padix = allocmy("", 0, 0); |
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Perl_allocmy currently does not support empty names because it blindly uses name[1]. It needs to be changed to check len first.
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Creates a new UNOP_AUX op type,
OP_MULTIPARAM, that handles all of the initial behaviour of assigning values to parameters of a subroutine signature out of values passed by the caller. This is created in a similar style to other multi-ops likeOP_MULTIDEREFandOP_MULTICONCATwhere the op's aux structure contains a sub-program of sorts, which describes all of the small details of operation.Also adds a LOGOP,
OP_PARAMTESTand UNOPOP_PARAMSTOREwhich are responsible for implementing the default expressions of optional parameters. These use theSvPADSTALEflag set on pad lexicals used as parameters to remember whether assignment has happened, ensuring that missing vs present-but-undef can be detected in a way that does not depend on counting arguments on the stack.This change is carefully designed to support two future ideas:
Named parameters as per PPC0024
"no-snails"; the performance optimisation that avoids storing incoming argument values in the
@_AV and instead consumes them directly from the stack--
This set of changes currently does not have a perldelta entry, because it doesn't directly make any changes that are end-user visible. However, since it is quite a significant internal change, I could be talked into writing an entry in the "internal changes" section anyway. Reviewers: Thoughts?