re-enable test-cases and get them all passing

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.

1 files changed, 2 insertions, 0 deletions

diff --git a/test/cases/compile_errors/condition_comptime_reason_explained.zig b/test/cases/compile_errors/condition_comptime_reason_explained.zig
index 332ae8afc8..d0193986a8 100644
--- a/test/cases/compile_errors/condition_comptime_reason_explained.zig
+++ b/test/cases/compile_errors/condition_comptime_reason_explained.zig
@@ -45,4 +45,6 @@ pub export fn entry2() void {
 // :22:13: error: unable to resolve comptime value
 // :22:13: note: condition in comptime switch must be comptime-known
 // :21:17: note: expression is evaluated at comptime because the function returns a comptime-only type 'tmp.S'
+// :2:12: note: struct requires comptime because of this field
+// :2:12: note: use '*const fn() void' for a function pointer type
 // :32:19: note: called from here