backport copy elision changes

This commit contains everything from the copy-elision-2
branch that does not have to do with copy elision directly,
but is generally useful for master branch.

 * All const values know their parents, when applicable, not
   just structs and unions.
 * Null pointers in const values are represented explicitly,
   rather than as a HardCodedAddr value of 0.
 * Rename "maybe" to "optional" in various code locations.
 * Separate DeclVarSrc and DeclVarGen
 * Separate PtrCastSrc and PtrCastGen
 * Separate CmpxchgSrc and CmpxchgGen
 * Represent optional error set as an integer, using the 0 value.
   In a const value, it uses nullptr.
 * Introduce type_has_one_possible_value and use it where applicable.
 * Fix debug builds not setting memory to 0xaa when storing
   undefined.
 * Separate the type of a variable from the const value of a variable.
 * Use copy_const_val where appropriate.
 * Rearrange structs to pack data more efficiently.
 * Move test/cases/* to test/behavior/*
 * Use `std.debug.assertOrPanic` in behavior tests instead of
   `std.debug.assert`.
 * Fix outdated slice syntax in docs.

1 files changed, 0 insertions, 82 deletions

diff --git a/test/behavior.zig b/test/behavior.zig
deleted file mode 100644
index 10cd08dad7..0000000000
--- a/test/behavior.zig
+++ /dev/null
@@ -1,82 +0,0 @@
-const builtin = @import("builtin");
-
-comptime {
-    _ = @import("cases/align.zig");
-    _ = @import("cases/alignof.zig");
-    _ = @import("cases/array.zig");
-    _ = @import("cases/asm.zig");
-    _ = @import("cases/atomics.zig");
-    _ = @import("cases/bitcast.zig");
-    _ = @import("cases/bool.zig");
-    _ = @import("cases/bswap.zig");
-    _ = @import("cases/bitreverse.zig");
-    _ = @import("cases/bugs/1076.zig");
-    _ = @import("cases/bugs/1111.zig");
-    _ = @import("cases/bugs/1277.zig");
-    _ = @import("cases/bugs/1322.zig");
-    _ = @import("cases/bugs/1381.zig");
-    _ = @import("cases/bugs/1421.zig");
-    _ = @import("cases/bugs/1442.zig");
-    _ = @import("cases/bugs/1486.zig");
-    _ = @import("cases/bugs/394.zig");
-    _ = @import("cases/bugs/655.zig");
-    _ = @import("cases/bugs/656.zig");
-    _ = @import("cases/bugs/726.zig");
-    _ = @import("cases/bugs/828.zig");
-    _ = @import("cases/bugs/920.zig");
-    _ = @import("cases/byval_arg_var.zig");
-    _ = @import("cases/cancel.zig");
-    _ = @import("cases/cast.zig");
-    _ = @import("cases/const_slice_child.zig");
-    _ = @import("cases/coroutine_await_struct.zig");
-    _ = @import("cases/coroutines.zig");
-    _ = @import("cases/defer.zig");
-    _ = @import("cases/enum.zig");
-    _ = @import("cases/enum_with_members.zig");
-    _ = @import("cases/error.zig");
-    _ = @import("cases/eval.zig");
-    _ = @import("cases/field_parent_ptr.zig");
-    _ = @import("cases/fn.zig");
-    _ = @import("cases/fn_in_struct_in_comptime.zig");
-    _ = @import("cases/for.zig");
-    _ = @import("cases/generics.zig");
-    _ = @import("cases/if.zig");
-    _ = @import("cases/import.zig");
-    _ = @import("cases/incomplete_struct_param_tld.zig");
-    _ = @import("cases/inttoptr.zig");
-    _ = @import("cases/ir_block_deps.zig");
-    _ = @import("cases/math.zig");
-    _ = @import("cases/merge_error_sets.zig");
-    _ = @import("cases/misc.zig");
-    _ = @import("cases/namespace_depends_on_compile_var/index.zig");
-    _ = @import("cases/new_stack_call.zig");
-    _ = @import("cases/null.zig");
-    _ = @import("cases/optional.zig");
-    _ = @import("cases/pointers.zig");
-    _ = @import("cases/popcount.zig");
-    _ = @import("cases/ptrcast.zig");
-    _ = @import("cases/pub_enum/index.zig");
-    _ = @import("cases/ref_var_in_if_after_if_2nd_switch_prong.zig");
-    _ = @import("cases/reflection.zig");
-    _ = @import("cases/sizeof_and_typeof.zig");
-    _ = @import("cases/slice.zig");
-    _ = @import("cases/struct.zig");
-    _ = @import("cases/struct_contains_null_ptr_itself.zig");
-    _ = @import("cases/struct_contains_slice_of_itself.zig");
-    _ = @import("cases/switch.zig");
-    _ = @import("cases/switch_prong_err_enum.zig");
-    _ = @import("cases/switch_prong_implicit_cast.zig");
-    _ = @import("cases/syntax.zig");
-    _ = @import("cases/this.zig");
-    _ = @import("cases/truncate.zig");
-    _ = @import("cases/try.zig");
-    _ = @import("cases/type_info.zig");
-    _ = @import("cases/undefined.zig");
-    _ = @import("cases/underscore.zig");
-    _ = @import("cases/union.zig");
-    _ = @import("cases/var_args.zig");
-    _ = @import("cases/void.zig");
-    _ = @import("cases/while.zig");
-    _ = @import("cases/widening.zig");
-    _ = @import("cases/bit_shifting.zig");
-}