cross compile the stage2 tests for the target that they work for

src-self-hosted/test.zig

@@ -29,6 +29,7 @@ pub const TestContext = struct {
         name: []const u8,
         src: [:0]const u8,
         expected_zir: []const u8,
+        cross_target: std.zig.CrossTarget,
     };
 
     pub fn addZIRCompareOutput(
@@ -47,6 +48,7 @@ pub const TestContext = struct {
     pub fn addZIRTransform(
         ctx: *TestContext,
         name: []const u8,
+        cross_target: std.zig.CrossTarget,
         src: [:0]const u8,
         expected_zir: []const u8,
     ) void {
@@ -54,6 +56,7 @@ pub const TestContext = struct {
             .name = name,
             .src = src,
             .expected_zir = expected_zir,
+            .cross_target = cross_target,
         }) catch unreachable;
     }
 
@@ -85,7 +88,8 @@ pub const TestContext = struct {
         }
         for (self.zir_transform_cases.items) |case| {
             std.testing.base_allocator_instance.reset();
-            try self.runOneZIRTransformCase(std.testing.allocator, root_node, case, native_info.target);
+            const info = try std.zig.system.NativeTargetInfo.detect(std.testing.allocator, case.cross_target);
+            try self.runOneZIRTransformCase(std.testing.allocator, root_node, case, info.target);
             try std.testing.allocator_instance.validate();
         }
     }

test/stage2/zir.zig

@@ -1,7 +1,15 @@
+const std = @import("std");
 const TestContext = @import("../../src-self-hosted/test.zig").TestContext;
+// self-hosted does not yet support PE executable files / COFF object files
+// or mach-o files. So we do the ZIR transform test cases cross compiling for
+// x86_64-linux.
+const linux_x64 = std.zig.CrossTarget{
+    .cpu_arch = .x86_64,
+    .os_tag = .linux,
+};
 
 pub fn addCases(ctx: *TestContext) void {
-    ctx.addZIRTransform("elemptr, add, cmp, condbr, return, breakpoint",
+    ctx.addZIRTransform("elemptr, add, cmp, condbr, return, breakpoint", linux_x64,
         \\@void = primitive(void)
         \\@usize = primitive(usize)
         \\@fnty = fntype([], @void, cc=C)
@@ -49,8 +57,8 @@ pub fn addCases(ctx: *TestContext) void {
         \\
     );
 
-    if (@import("std").Target.current.os.tag != .linux or
+    if (std.Target.current.os.tag != .linux or
-        @import("std").Target.current.cpu.arch != .x86_64)
+        std.Target.current.cpu.arch != .x86_64)
     {
         // TODO implement self-hosted PE (.exe file) linking
         // TODO implement more ZIR so we don't depend on x86_64-linux