This reverts commit b822e841cda0adabe3fec260ff51c18508f7ee32, reversing
changes made to 0c99ba1eab63865592bb084feb271cd4e4b0357e.
This caused a CI failure when it landed in master branch.
This commit does two things which seem unrelated at first, but,
together, solve a miscompilation, and potentially slightly speed up
compiler perf, at the expense of making #2765 trickier to implement in
the future.
Sema: avoid returning a false positive for whether an inferred error set
is comptime-known to be empty.
AstGen: mark function calls as not being interested in a result
location. This prevents the test case "ret_ptr doesn't cause own
inferred error set to be resolved" from being regressed. If we want to
accept and implement #2765 in the future, it will require solving this
problem a different way, but the principle of YAGNI tells us to go ahead
with this change.
Old ZIR looks like this:
%97 = ret_ptr()
%101 = store_node(%97, %100)
%102 = load(%97)
%103 = ret_is_non_err(%102)
New ZIR looks like this:
%97 = ret_type()
%101 = as_node(%97, %100)
%102 = ret_is_non_err(%101)
closes#15669
Most of this migration was performed automatically with `zig fmt`. There
were a few exceptions which I had to manually fix:
* `@alignCast` and `@addrSpaceCast` cannot be automatically rewritten
* `@truncate`'s fixup is incorrect for vectors
* Test cases are not formatted, and their error locations change
This reverts commit 5aa9628de3c6637f45b9d8cf8cbd19c422a74f6f.
This is a breaking language change and I do not agree with it. Please go
through the proposal process on this one.
This change extends the "lifetime" of the error return trace associated
with an error to continue throughout the block of a `const` variable
that it is assigned to.
This is necessary to support patterns like this one in test_runner.zig:
```zig
const result = foo();
if (result) |_| {
// ... success logic
} else |err| {
// `foo()` should be included in the error trace here
return error.TestFailed;
}
```
To make this happen, the majority of the error return trace popping logic
needed to move into Sema, since `const x = foo();` cannot be examined
syntactically to determine whether it modifies the error return trace. We
also have to make sure not to delete pertinent block information before it
makes it to Sema, so that Sema can pop/restore around blocks correctly.
* Why do this only for `const` and not `var`? *
There is room to relax things for `var`, but only a little bit. We could
do the same thing we do for const and keep the error trace alive for the
remainder of the block where the *assignment* happens. Any wider scope
would violate the stack discipline for traces, so it's not viable.
In the end, I decided the most consistent behavior for the user is just
to kill all error return traces assigned to a mutable `var`.
Previously, when lowering AIR instructions `wrap_errunion_payload`,
`wrap_errunion_err`, and `wrap_optional`, the LLVM backend would create
an alloca instruction to store the result, but did not set the alignment
on it. This caused UB which went undetected for a long time until we
started enabling the stack protector.
Closes#12594
Unblocks #12508
Inspires #12634
Tests passed locally:
* test-behavior
* test-cases
