CI: skip test-incremental on Windows

Tracked by #22510

build.zig

@@ -97,6 +97,7 @@ pub fn build(b: *std.Build) !void {
     const skip_darwin = b.option(bool, "skip-darwin", "Main test suite skips targets with darwin OSs") orelse false;
     const skip_linux = b.option(bool, "skip-linux", "Main test suite skips targets with linux OS") orelse false;
     const skip_llvm = b.option(bool, "skip-llvm", "Main test suite skips targets that use LLVM backend") orelse false;
+    const skip_test_incremental = b.option(bool, "skip-test-incremental", "Main test step omits dependency on test-incremental step") orelse false;
 
     const only_install_lib_files = b.option(bool, "lib-files-only", "Only install library files") orelse false;
 
@@ -609,7 +610,7 @@ pub fn build(b: *std.Build) !void {
 
     const test_incremental_step = b.step("test-incremental", "Run the incremental compilation test cases");
     try tests.addIncrementalTests(b, test_incremental_step);
-    test_step.dependOn(test_incremental_step);
+    if (!skip_test_incremental) test_step.dependOn(test_incremental_step);
 
     if (tests.addLibcTests(b, .{
         .optimize_modes = optimization_modes,

ci/x86_64-windows-debug.ps1

@@ -59,6 +59,7 @@ Write-Output "Main test suite..."
   -Dstatic-llvm `
   -Dskip-non-native `
   -Dskip-release `
+  -Dskip-test-incremental `
   -Denable-symlinks-windows `
   --test-timeout 30m
 CheckLastExitCode

ci/x86_64-windows-release.ps1

@@ -58,6 +58,7 @@ Write-Output "Main test suite..."
   --search-prefix "$PREFIX_PATH" `
   -Dstatic-llvm `
   -Dskip-non-native `
+  -Dskip-test-incremental `
   -Denable-symlinks-windows `
   --test-timeout 30m
 CheckLastExitCode

test/incremental/add_decl

@@ -0,0 +1,63 @@
+#target=x86_64-linux-selfhosted
+#target=x86_64-windows-selfhosted
+#target=x86_64-linux-cbe
+#target=x86_64-windows-cbe
+//#target=wasm32-wasi-selfhosted
+#update=initial version
+#file=main.zig
+const std = @import("std");
+pub fn main() !void {
+    try std.fs.File.stdout().writeAll(foo);
+}
+const foo = "good morning\n";
+#expect_stdout="good morning\n"
+
+#update=add new declaration
+#file=main.zig
+const std = @import("std");
+pub fn main() !void {
+    try std.fs.File.stdout().writeAll(foo);
+}
+const foo = "good morning\n";
+const bar = "good evening\n";
+#expect_stdout="good morning\n"
+
+#update=reference new declaration
+#file=main.zig
+const std = @import("std");
+pub fn main() !void {
+    try std.fs.File.stdout().writeAll(bar);
+}
+const foo = "good morning\n";
+const bar = "good evening\n";
+#expect_stdout="good evening\n"
+
+#update=reference missing declaration
+#file=main.zig
+const std = @import("std");
+pub fn main() !void {
+    try std.fs.File.stdout().writeAll(qux);
+}
+const foo = "good morning\n";
+const bar = "good evening\n";
+#expect_error=main.zig:3:39: error: use of undeclared identifier 'qux'
+
+#update=add missing declaration
+#file=main.zig
+const std = @import("std");
+pub fn main() !void {
+    try std.fs.File.stdout().writeAll(qux);
+}
+const foo = "good morning\n";
+const bar = "good evening\n";
+const qux = "good night\n";
+#expect_stdout="good night\n"
+
+#update=remove unused declarations
+#file=main.zig
+const std = @import("std");
+pub fn main() !void {
+    try std.fs.File.stdout().writeAll(qux);
+}
+const qux = "good night\n";
+#expect_stdout="good night\n"