feat: write_source_files windows implementation

lib/private/write_source_files.bzl

@@ -8,30 +8,14 @@ _write_source_files_attrs = {
     "is_windows": attr.bool(mandatory = True),
 }
 
-def _write_source_files_impl(ctx):
-    if ctx.attr.is_windows:
-        fail("write_source_file is not yet implemented for windows")
-
-    if (len(ctx.attr.in_files) != len(ctx.attr.out_files)):
-        fail("in_files and out_files must be the same length")
-
-    for i in range(len(ctx.attr.in_files)):
-        out_file_label = ctx.attr.out_files[i].label
-        if is_external_label(out_file_label):
-            fail("out file %s must be a source file in the user workspace" % out_file_label)
-
-        if not ctx.files.out_files[i].is_source:
-            fail("out file %s must be a source file, not a generated file" % out_file_label)
-
-        if out_file_label.package != ctx.label.package:
-            fail("out file %s (in package '%s') must be a source file within the target's package: '%s'" % (out_file_label, out_file_label.package, ctx.label.package))
-
+def _write_source_files_sh(ctx):
     updater = ctx.actions.declare_file(
         ctx.label.name + "_update.sh",
     )
 
     ctx.actions.write(
         output = updater,
+        is_executable = True,
         content = """
 #!/usr/bin/env bash
 set -o errexit -o nounset -o pipefail
@@ -54,6 +38,67 @@ chmod 644 "$out"
         ]),
     )
 
+    return updater
+
+def _write_source_files_bat(ctx):
+    updater = ctx.actions.declare_file(
+        ctx.label.name + "_update.bat",
+    )
+
+    content = """
+@rem Generated by write_source_files.bzl, do not edit.
+@echo off
+set runfiles_dir=%cd%
+if defined BUILD_WORKSPACE_DIRECTORY (
+    cd %BUILD_WORKSPACE_DIRECTORY%
+)
+""" + "\n".join(["""
+set in=%runfiles_dir%\\{in_file}
+set out={out_file}
+
+if not defined BUILD_WORKSPACE_DIRECTORY (
+    @rem Because there's no sandboxing in windows, if we copy over the target
+    @rem file's symlink it will get copied back into the source directory
+    @rem during tests. Work around this in tests by deleting the target file
+    @rem symlink before copying over it.
+    del %out%
+)
+
+echo Copying %in% to %out% in %cd%
+copy %in% %out% >NUL
+""".format(in_file = ctx.files.in_files[i].short_path.replace("/", "\\"), out_file = ctx.files.out_files[i].short_path).replace("/", "\\")
+            for i in range(len(ctx.attr.in_files))
+        ])
+        
+    content = content.replace("\n", "\r\n")
+
+    ctx.actions.write(
+        output = updater,
+        is_executable = True,
+        content = content,
+    )
+    return updater
+
+def _write_source_files_impl(ctx):
+    if (len(ctx.attr.in_files) != len(ctx.attr.out_files)):
+        fail("in_files and out_files must be the same length")
+
+    for i in range(len(ctx.attr.in_files)):
+        out_file_label = ctx.attr.out_files[i].label
+        if is_external_label(out_file_label):
+            fail("out file %s must be a source file in the user workspace" % out_file_label)
+
+        if not ctx.files.out_files[i].is_source:
+            fail("out file %s must be a source file, not a generated file" % out_file_label)
+
+        if out_file_label.package != ctx.label.package:
+            fail("out file %s (in package '%s') must be a source file within the target's package: '%s'" % (out_file_label, out_file_label.package, ctx.label.package))
+
+    if ctx.attr.is_windows:
+        updater = _write_source_files_bat(ctx)
+    else:
+        updater = _write_source_files_sh(ctx)
+
     return DefaultInfo(
         executable = updater,
         runfiles = ctx.runfiles(files = ctx.files.in_files),

lib/tests/write_source_files/write_source_files_test.bzl

@@ -9,7 +9,7 @@ _write_source_files = rule(
     executable = True,
 )
 
-def _impl(ctx):
+def _impl_sh(ctx):
     test = ctx.actions.declare_file(
         ctx.label.name + "_test.sh",
     )
@@ -55,9 +55,86 @@ assert_same() {
         ]),
     )
 
+    return test
+
+def _impl_bat(ctx):
+    test = ctx.actions.declare_file(
+        ctx.label.name + "_test.bat",
+    )
+
+    # BUG: Windows is having trouble executing the symlink to the write_source_files executable,
+    # but it is able to execute the actual output script so point to that for now.
+    #
+    # What we would use if this bug didn't exist:
+    #    write_source_files = ctx.executable.write_source_files_target.short_path.replace("/", "\\")
+    #
+    # Instead back out of the runfiles execution directory:
+    #    write_to_source_files_test_test.bat.runfiles/aspect_bazel_lib
+    # And point to the output script.
+    write_source_files = "..\\..\\%s" % ctx.executable.write_source_files_target.basename
+
+    content = """
+@rem Generated by copy_to_directory.bzl, do not edit.
+@echo off
+@rem Check that in and out files are different
+""" + "\n".join(["""
+call :assert_different {in_file}, {out_file}
+if %errorlevel% neq 0 exit /b 1
+""".format(
+                in_file = ctx.files.in_files[i].short_path.replace("/", "\\"),
+                out_file = ctx.files.out_files[i].short_path.replace("/", "\\"),
+            )
+            for i in range(len(ctx.files.in_files))
+        ]) + """
+@rem Write to the source files
+call {write_source_files}
+if %errorlevel% neq 0 exit /b 1
+
+@rem Check that in and out files are the same
+""".format(write_source_files = write_source_files) + "\n".join(["""
+call :assert_same {in_file}, {out_file}
+if %errorlevel% neq 0 exit /b 1
+""".format(
+                in_file = ctx.files.in_files[i].short_path.replace("/", "\\"),
+                out_file = ctx.files.out_files[i].short_path.replace("/", "\\"),
+            )
+            for i in range(len(ctx.files.in_files))
+        ]) + """
+exit /b 0
+
+:assert_different
+fc /b %~1 %~2 > nul
+if %errorlevel% equ 1 exit /b 0
+echo Error: %~1 and %~2 are not different
+exit /b 1
+
+:assert_same
+fc /b %~1 %~2 > nul
+if %errorlevel% equ 0 exit /b 0
+echo Error: %~1 and %~2 are not the same
+exit /b 1
+"""
+    content = content.replace("\n", "\r\n")
+
+    ctx.actions.write(
+        output = test,
+        is_executable = True,
+        content = content
+    )
+
+    return test
+
+def _impl(ctx):
+    if ctx.attr.is_windows:
+        test = _impl_bat(ctx)
+    else:
+        test = _impl_sh(ctx)
+
     return DefaultInfo(
         executable = test,
-        runfiles = ctx.runfiles(files = [ctx.file.write_source_files_target] + ctx.files.in_files + ctx.files.out_files),
+        runfiles = ctx.runfiles(
+            files = [ctx.executable.write_source_files_target] + ctx.files.in_files + ctx.files.out_files,
+        ),
     )
 
 _write_source_files_test = rule(
@@ -66,7 +143,9 @@ _write_source_files_test = rule(
         "write_source_files_target": attr.label(
             allow_single_file = True,
             executable = True,
-            cfg = "exec",
+            # Should be cfg = "exec" but a bazel bug causes a wrong executable symlink on windows
+            cfg = "target",
+            mandatory = True,
         ),
         "out_files": attr.label_list(
             allow_files = True,
@@ -78,6 +157,7 @@ _write_source_files_test = rule(
             allow_empty = False,
             mandatory = True,
         ),
+        "is_windows": attr.bool(mandatory = True),
     },
     test = True,
 )
@@ -89,7 +169,10 @@ def write_source_files_test(name, in_files, out_files):
         name = name + "_updater",
         out_files = out_files,
         in_files = in_files,
-        is_windows = False,
+        is_windows = select({
+            "@bazel_tools//src/conditions:host_windows": True,
+            "//conditions:default": False,
+        }),
     )
 
     # Note that for testing we update the source files in the sandbox,
@@ -99,4 +182,8 @@ def write_source_files_test(name, in_files, out_files):
         write_source_files_target = name + "_updater",
         out_files = out_files,
         in_files = in_files,
+        is_windows = select({
+            "@bazel_tools//src/conditions:host_windows": True,
+            "//conditions:default": False,
+        }),
     )