fix: Windows batch file line endings to avoid cmd parsing bug

lib/private/diff_test.bzl

@@ -68,20 +68,20 @@ def _diff_test_impl(ctx):
         template = ctx.file._diff_test_tmpl_bat
         file1_path = to_rlocation_path(ctx, file1)
         file2_path = to_rlocation_path(ctx, file2)
-        fail_msg = ["@echo" + (" " + line if line.strip() != "" else ".") for line in ctx.attr.failure_message[:-1].split("\n")]
+        fail_msg = "\r\n".join(["@echo" + (" " + line if line.strip() != "" else ".") for line in ctx.attr.failure_message[:-1].splitlines()])
     else:
         test_suffix = "-test.sh"
         template = ctx.file._diff_test_tmpl_sh
-        fail_msg = ctx.attr.failure_message.split("\n")
+        fail_msg = ctx.attr.failure_message
 
     test_bin = ctx.actions.declare_file(ctx.label.name + test_suffix)
     ctx.actions.expand_template(
         template = template,
         output = test_bin,
         substitutions = {
-            "{BATCH_RLOCATION_FUNCTION}": BATCH_RLOCATION_FUNCTION,
+            "{BATCH_RLOCATION_FUNCTION}": "\r\n".join(BATCH_RLOCATION_FUNCTION.splitlines()),
             "{name}": ctx.attr.name,
-            "{fail_msg}": "\n".join(fail_msg),
+            "{fail_msg}": fail_msg,
             "{file1}": file1_path,
             "{file2}": file2_path,
             "{file1_sub_path}": file1_sub_path,

lib/private/diff_test_tmpl.bat

@@ -1,107 +1,107 @@
-@rem @generated by @bazel_lib//lib/private:diff_test.bzl
-@echo off
-:: TODO: Add support for XML_OUTPUT_FILE like in diff_test_tmpl.sh
-SETLOCAL ENABLEEXTENSIONS
-SETLOCAL ENABLEDELAYEDEXPANSION
-set RUNFILES_MANIFEST_ONLY=1
-{BATCH_RLOCATION_FUNCTION}
-set MF=%RUNFILES_MANIFEST_FILE:/=\\%
-set PATH=%SYSTEMROOT%\\system32
-call :rlocation {file1} RF1
-call :rlocation {file2} RF2
-set RF1=!RF1:/=\!
-set RF2=!RF2:/=\!
-if "{file1_sub_path}" neq "" (
-  set RF1=!RF1!\\{file1_sub_path}
-)
-if "{file2_sub_path}" neq "" (
-  set RF2=!RF2!\\{file2_sub_path}
-)
-set DF1=0
-set DF2=0
-if exist "!RF1!\\*" (
-  set DF1=1
-)
-if exist "!RF2!\\*" (
-  set DF2=1
-)
-if %DF1% equ 1 (
-  if %DF2% equ 0 (
-    echo>&2 ERROR: Cannot compare directory "{file1}" and a file "{file2}"
-    exit /b 1
-  )
-)
-if %DF1% equ 0 (
-  if %DF2% equ 1 (
-    echo>&2 ERROR: Cannot compare file "{file1}" and a directory "{file2}"
-    exit /b 1
-  )
-)
-set DFX=0
-if %DF1% equ 1 (
-  if %DF2% equ 1 (
-    set DFX=1
-  )
-)
-
-if %DFX% equ 0 goto :compare_files
-:compare_directories
-for /f "delims=" %%F in (
-  'echo "."^&forfiles /s /p "!RF1!" /m "*" /c "cmd /c echo @relpath"'
-) do (
-  if not exist "!RF2!\\%%~F" (
-    echo>&2 FAIL: file "%%~F" exists in "{file1}" and not in "{file2}".
-    GOTO fail
-  )
-  if not exist "!RF1!\\%%~F\\*" (
-    fc.exe "!RF1!\\%%~F" "!RF2!\\%%~F" 2>NUL 1>NUL
-    if !ERRORLEVEL! neq 0 (
-      if !ERRORLEVEL! equ 1 (
-        echo>&2 FAIL: files "!RF1!\\%%~F" and "!RF2!\\%%~F" differ.
-        set RF1=!RF1!\\%%~F
-        set RF2=!RF2!\\%%~F
-        GOTO fail
-      ) else (
-        fc.exe "!RF1!\\%%~F" "!RF2!\\%%~F"
-        GOTO fail
-      )
-    )
-  )
-)
-for /f "delims=" %%F in (
-  'echo "."^&forfiles /s /p "!RF2!" /m "*" /c "cmd /c echo @relpath"'
-) do (
-  if not exist "!RF1!\\%%~F" (
-    echo>&2 FAIL: file "%%~F" exists in "{file2}" and not in "{file1}".
-    GOTO fail
-  )
-)
-goto :success
-
-:compare_files
-echo compare_files
-fc.exe "!RF1!" "!RF2!" 2>NUL 1>NUL
-set result=%ERRORLEVEL%
-if !result! neq 0 (
-  if !result! equ 1 (
-    echo>&2 FAIL: files "!RF1!" and "!RF2!" differ.
-    goto :fail
-  ) else (
-    echo fc.exe "!RF1!" "!RF2!"
-    fc.exe "!RF1!" "!RF2!"
-    set result=%ERRORLEVEL%
-    exit /b !result!
-  )
-) else (
-  echo fc returned 0
-)
-:success
-exit /b 0
-
-:fail
-{fail_msg}
-echo To see differences run:
-echo.
-echo     diff "!RF1!" "!RF2!"
-echo.
-exit /b 1
+@rem @generated by @bazel_lib//lib/private:diff_test.bzl
+@echo off
+:: TODO: Add support for XML_OUTPUT_FILE like in diff_test_tmpl.sh
+SETLOCAL ENABLEEXTENSIONS
+SETLOCAL ENABLEDELAYEDEXPANSION
+set RUNFILES_MANIFEST_ONLY=1
+{BATCH_RLOCATION_FUNCTION}
+set MF=%RUNFILES_MANIFEST_FILE:/=\\%
+set PATH=%SYSTEMROOT%\\system32
+call :rlocation {file1} RF1
+call :rlocation {file2} RF2
+set RF1=!RF1:/=\!
+set RF2=!RF2:/=\!
+if "{file1_sub_path}" neq "" (
+  set RF1=!RF1!\\{file1_sub_path}
+)
+if "{file2_sub_path}" neq "" (
+  set RF2=!RF2!\\{file2_sub_path}
+)
+set DF1=0
+set DF2=0
+if exist "!RF1!\\*" (
+  set DF1=1
+)
+if exist "!RF2!\\*" (
+  set DF2=1
+)
+if %DF1% equ 1 (
+  if %DF2% equ 0 (
+    echo>&2 ERROR: Cannot compare directory "{file1}" and a file "{file2}"
+    exit /b 1
+  )
+)
+if %DF1% equ 0 (
+  if %DF2% equ 1 (
+    echo>&2 ERROR: Cannot compare file "{file1}" and a directory "{file2}"
+    exit /b 1
+  )
+)
+set DFX=0
+if %DF1% equ 1 (
+  if %DF2% equ 1 (
+    set DFX=1
+  )
+)
+
+if %DFX% equ 0 goto :compare_files
+:compare_directories
+for /f "delims=" %%F in (
+  'echo "."^&forfiles /s /p "!RF1!" /m "*" /c "cmd /c echo @relpath"'
+) do (
+  if not exist "!RF2!\\%%~F" (
+    echo>&2 FAIL: file "%%~F" exists in "{file1}" and not in "{file2}".
+    GOTO fail
+  )
+  if not exist "!RF1!\\%%~F\\*" (
+    fc.exe "!RF1!\\%%~F" "!RF2!\\%%~F" 2>NUL 1>NUL
+    if !ERRORLEVEL! neq 0 (
+      if !ERRORLEVEL! equ 1 (
+        echo>&2 FAIL: files "!RF1!\\%%~F" and "!RF2!\\%%~F" differ.
+        set RF1=!RF1!\\%%~F
+        set RF2=!RF2!\\%%~F
+        GOTO fail
+      ) else (
+        fc.exe "!RF1!\\%%~F" "!RF2!\\%%~F"
+        GOTO fail
+      )
+    )
+  )
+)
+for /f "delims=" %%F in (
+  'echo "."^&forfiles /s /p "!RF2!" /m "*" /c "cmd /c echo @relpath"'
+) do (
+  if not exist "!RF1!\\%%~F" (
+    echo>&2 FAIL: file "%%~F" exists in "{file2}" and not in "{file1}".
+    GOTO fail
+  )
+)
+goto :success
+
+:compare_files
+echo compare_files
+fc.exe "!RF1!" "!RF2!" 2>NUL 1>NUL
+set result=%ERRORLEVEL%
+if !result! neq 0 (
+  if !result! equ 1 (
+    echo>&2 FAIL: files "!RF1!" and "!RF2!" differ.
+    goto :fail
+  ) else (
+    echo fc.exe "!RF1!" "!RF2!"
+    fc.exe "!RF1!" "!RF2!"
+    set result=%ERRORLEVEL%
+    exit /b !result!
+  )
+) else (
+  echo fc returned 0
+)
+:success
+exit /b 0
+
+:fail
+{fail_msg}
+echo To see differences run:
+echo.
+echo     diff "!RF1!" "!RF2!"
+echo.
+exit /b 1

lib/private/write_source_file.bzl

@@ -390,7 +390,8 @@ if !ERRORLEVEL! neq 0 (
     ctx.actions.write(
         output = updater,
         is_executable = True,
-        content = "\n".join(contents),
+        # since `contents` already contains some \n, splitting lines first avoids bogus \r\r\n
+        content = "\r\n".join([line for content in contents for line in content.splitlines()]),
     )
     return updater
 

lib/tests/bats/BUILD.bazel

@@ -1,3 +1,4 @@
+load("@bazel_skylib//rules:native_binary.bzl", "native_test")
 load("//lib:bats.bzl", "bats_test")
 
 NOT_WINDOWS = select({
@@ -15,6 +16,14 @@ bats_test(
     target_compatible_with = NOT_WINDOWS,
 )
 
+# Verify line endings in the launcher script generated by bats_test: CRLF-only on Windows, LF-only otherwise
+native_test(
+    name = "script_newlines_test",
+    src = "//lib/tests/check_newlines",
+    args = ["$(rlocationpath :basic)"],
+    data = [":basic"],
+)
+
 bats_test(
     name = "env",
     size = "small",

lib/tests/check_newlines/BUILD.bazel

@@ -0,0 +1,9 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_binary")
+
+go_binary(
+    name = "check_newlines",
+    testonly = True,
+    srcs = ["main.go"],
+    visibility = ["//lib/tests:__subpackages__"],
+    deps = ["@io_bazel_rules_go//go/runfiles"],
+)

lib/tests/check_newlines/main.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"runtime"
+
+	"github.com/bazelbuild/rules_go/go/runfiles"
+)
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Fprintln(os.Stderr, "Usage: check_newlines <script>")
+		os.Exit(1)
+	}
+
+	r, err := runfiles.New()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to initialize runfiles: %v\n", err)
+		os.Exit(1)
+	}
+
+	script, err := r.Rlocation(os.Args[1])
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to locate %s in runfiles: %v\n", os.Args[1], err)
+		os.Exit(1)
+	}
+
+	content, err := os.ReadFile(script)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to read %s: %v\n", script, err)
+		os.Exit(1)
+	}
+
+	cr := bytes.Count(content, []byte("\r"))
+	lf := bytes.Count(content, []byte("\n"))
+	crlf := bytes.Count(content, []byte("\r\n"))
+	if runtime.GOOS == "windows" {
+		if cr != lf || cr != crlf {
+			fmt.Fprintf(os.Stderr, "%s contains non-Windows line endings (\\r=%d, \\n=%d, \\r\\n=%d)\n", script, cr, lf, crlf)
+			os.Exit(1)
+		}
+	} else if cr > 0 {
+		fmt.Fprintf(os.Stderr, "%s contains Windows line endings (\\r=%d, \\n=%d, \\r\\n=%d)\n", script, cr, lf, crlf)
+		os.Exit(1)
+	}
+}

lib/tests/diff_test/BUILD.bazel

@@ -0,0 +1,37 @@
+load("@bazel_lib//lib:diff_test.bzl", "diff_test")
+load("@bazel_skylib//rules:native_binary.bzl", "native_test")
+load("@bazel_skylib//rules:write_file.bzl", "write_file")
+
+# Create two simple files to compare
+write_file(
+    name = "gen_file1",
+    out = "file1.txt",
+    content = [
+        "line1",
+        "line2",
+    ],
+)
+
+write_file(
+    name = "gen_file2",
+    out = "file2.txt",
+    content = [
+        "line1",
+        "line2",
+    ],
+)
+
+# Have diff_test generate a script
+diff_test(
+    name = "gen_script",
+    file1 = ":file1.txt",
+    file2 = ":file2.txt",
+)
+
+# Verify line endings in the script generated by diff_test: CRLF-only on Windows, LF-only otherwise
+native_test(
+    name = "script_newlines_test",
+    src = "//lib/tests/check_newlines",
+    args = ["$(rlocationpath :gen_script)"],
+    data = [":gen_script"],
+)