This rewrite improves some error messages, hugely simplifies the logic,
and fixes several bugs. One of these bugs is technically a new rule
which Andrew and I agreed on: if a parameter has a comptime-only type
but is not declared `comptime`, then the corresponding call argument
should not be *evaluated* at comptime; only resolved. Implementing this
required changing how function types work a little, which in turn
required allowing a new kind of function coercion for some generic use
cases: function coercions are now allowed to implicitly *remove*
`comptime` annotations from parameters with comptime-only types. This is
okay because removing the annotation affects only the call site.
Resolves: #22262
Currently, the compiler (like @typeName) writes it `fn(...) Type` but
zig fmt writes it `fn (...) Type` (notice the space after `fn`).
This inconsistency is now resolved and function types are consistently
written the zig fmt way. Before this there were more `fn (...) Type`
occurrences than `fn(...) Type` already.
Instead of using `zig test` to build a special version of the compiler
that runs all the test-cases, the zig build system is now used as much
as possible - all with the basic steps found in the standard library.
For incremental compilation tests (the ones that look like foo.0.zig,
foo.1.zig, foo.2.zig, etc.), a special version of the compiler is
compiled into a utility executable called "check-case" which checks
exactly one sequence of incremental updates in an independent
subprocess. Previously, all incremental and non-incremental test cases
were done in the same test runner process.
The compile error checking code is now simpler, but also a bit
rudimentary, and so it additionally makes sure that the actual compile
errors do not include *extra* messages, and it makes sure that the
actual compile errors output in the same order as expected. It is also
based on the "ends-with" property of each line rather than the previous
logic, which frankly I didn't want to touch with a ten-meter pole. The
compile error test cases have been updated to pass in light of these
differences.
Previously, 'error' mode with 0 compile errors was used to shoehorn in a
different kind of test-case - one that only checks if a piece of code
compiles without errors. Now there is a 'compile' mode of test-cases,
and 'error' must be only used when there are greater than 0 errors.
link test cases are updated to omit the target object format argument
when calling checkObject since that is no longer needed.
The test/stage2 directory is removed; the 2 files within are moved to be
directly in the test/ directory.
