Just replacing AUTOUPDATE with NOAUTOUPDATE, and removing the autoupdate
script. Tests will still run, but autoupdate may need to be fixed if
significant changes are made.
I noticed this while trying to autoupdate for #4007 (because we verify
that tests have been autoupdated). Autoupdate was likely broken by
#3449.
Trying to run with no changes gives:
```
CHECK failure at testing/file_test/file_test_base.cpp:801: !absl::GetFlag(FLAGS_test_targets_file).empty(): Missing --test_targets_file.
```
This is because the `file_test` rule creates a file with test inputs
that it runs with, which the prebuilt binary doesn't provide.
A local kludge to create a `file_test` target not using prebuilt_binary
showed another error:
```
: CommandLine Error: Option ': CommandLine Error: Option 'parser_debug' registered more than once!
LLVM ERROR: inconsistency in registered CommandLine options
trace_phase' registered more than once!
LLVM ERROR: inconsistency in registered CommandLine options
```
I'm thinking here that the explorer code hasn't been in enough use, and
we're seeing some rot as a consequence. Rather than trying to maintain
it, I'm suggesting to go with NOAUTOUPDATE.
Per #257, we should be treating unformedness as all-or-nothing, rather than being a per-field or per-array-element property. Previously we initialized an array with no explicit initializer as containing a sequence of uninitialized values, but that led to crashes when attempting to access those values, as the checks for reading an uninitialized value only expected values to be uninitialized at the top level.
Also, we had existing tests that attempt to store to an element of an uninitialized array. We now detect that and treat it as UB during evaluation, rather than crashing due to trying to perform field access into an uninitialized value.
Finally, many of these problems can be detected statically, but the resolve_unformed pass wasn't catching them because it missed a few expression and declaration forms. Support for those cases has been added too. This causes the pass to recurse more often, and in particular our existing recursion test started hitting a stack overflow after this, so resolve_unformed now uses `RunWithExtraStack`. In passing, remove the need to explicitly tell `RunWithExtraStack` the return type, and infer it as the return type of the callable instead.
Jon Ross-Perkins
Richard Smith