I achieved this through a major refactor of the logic of analyzeMinMax.
This change should be compatible with vectors of comptime_int, which
Andrew said are supposed to work (but which currently do not).
We now resolve undefined symbols during incremental-compilation
where we discard the current symbol if we detect we found
an existing symbol which is not the one currently being updated.
The symbol will always be discarded in favor of the existing symbol
in such a case.
When lowering a decl value we verify whether its owner decl index
equals to the decl index of the decl being lowered. When this is not
the case, we are lowering an alias. So instead, we will now lower
the owner decl instead and call its symbol to ensure its type
is being correctly generated.
When compiling Zig code using the Wasm backend, we would previously
incorrectly resolve exported symbols as it would not correctly remove
existing symbols if they were to be overwritten. This meant that
undefined symbols could cause collisions although they should be
resolved by the exported symbol.
Calling into coercion logic here is a little opaque, and more to the
point wholly unnecessary. Instead, the (very short) logic is now
implemented directly in Sema.
Resolves: #16033
Previously, this logic was split between Sema.coerceValueInMemory and
InternPool.getCoerced. This led to issues when trying to coerce e.g. an
optional containing an aggregate, because we'd call through to
InternPool's version which only recurses on itself so could not coerce
aggregates. Unifying them is fairly simple, and also simplified a bit of
logic in Sema.
Also fixes a key lifetime bug in aggregate coercion.
This allows tuples whose fields are in-memory coercible to themselves be
coerced in memory. No InMemoryCoercionResult field has been added, so in
future one could be added to improve error messages.
The existing logic for peer type resolution was quite convoluted and
buggy. This rewrite makes it much more resilient, readable, and
extensible. The algorithm works by first iterating over the types to
select a "strategy", then applying that strategy, possibly applying peer
resolution recursively.
Several new tests have been added to cover cases which the old logic did
not correctly handle.
Resolves: #15138Resolves: #15644Resolves: #15693Resolves: #15709Resolves: #15752
To do this, I expanded SwitchProngSrc a bit. Several of the tags there
aren't actually used by any current errors, but they're there for
consistency and if we ever need them.
Also delete a now-redundant test and fix another.
This is a bit harder than it seems at first glance. Actually resolving
the type is the easy part: the interesting thing is actually getting the
capture value. We split this into three cases:
* If all payload types are the same (as is required in status quo), we
can just do what we already do: get the first field value.
* If all payloads are in-memory coercible to the resolved type, we still
fetch the first field, but we also emit a `bitcast` to convert to the
resolved type.
* Otherwise, we need to handle each case separately. We emit a nested
`switch_br` which, for each possible case, gets the corresponding
union field, and coerces it to the resolved type. As an optimization,
the inner switch's 'else' prong is used for any peer which is
in-memory coercible to the target type, and the bitcast approach
described above is used.
Pointer captures have the additional constraint that all payload types
must be in-memory coercible to the resolved type.
Resolves: #2812
This finishes the process of consolidating switch expressions in ZIR
into as simple and compact a representation as is possible. There are
now just two ZIR tags dedicated to switch expressions: switch_block and
switch_block_ref, with the latter being for an operand passed by
reference.
This is a follow-up to a previous commit which eliminated switch_capture
and switch_capture_ref. All captures are now handled directly by
`switch_block`, which has also eliminated some unnecessary Block data in
Sema.
These tags are unnecessary, as this information can be more efficiently
encoded within the switch_block instruction itself. We also use a neat
little trick to avoid needing a dummy instruction (like is used for
errdefer captures): since the switch_block itself cannot otherwise be
referenced within a prong, we can repurpose its index within prongs to
refer to the captured value.
By indexing from the very first switch case rather than into scalar and
multi cases separately, the instructions for capturing in multi cases
become unnecessary, freeing up 2 ZIR tags.
Long term, linker backends will need to manage their own string tables
for things like this because my mandate is: no long-lived pointers
allowed in any of the codepaths touched by incremental compilation, so
that we can serialize and deserialize trivially.
Short term, I solved this with a couple calls to Allocator.dupe,
incurring some harmless leaks.
By correctly handling comptime-only types appearing in non-comptime
parameters (when the parameter is either anytype or generic), this
avoids an index out of bounds later when later filling out
`monomorphed_args` using what used to be slightly different logic.
These are frequently invalidated whenever a string is interned, so avoid
creating pointers to `string_bytes` wherever possible. This is an
attempt to fix random CI failures.
