std/io/os/temp_directory.c3: fix INVALID_PATH in Win32 native_temp_directory (#2762)

* std/io/os/temp_directory.c3: fix INVALID_PATH in Windows native_temp_directory

- Use the actual length from GetTempPathW for Windows temp path slice
- We can remove the workaround in the test_suite_runner for WIN32 and
create all directories in %temp% now

* Updated releasenotes.

---------

Co-authored-by: Christoffer Lerno <christoffer@aegik.com>

lib/std/io/os/temp_directory.c3

@@ -122,9 +122,10 @@ fn Path? native_temp_directory(Allocator allocator) @if(env::WIN32) => @pool()
 {
 	Win32_DWORD len = win32::getTempPathW(0, null);
 	if (!len) return io::GENERAL_ERROR?;
-	Char16[] buff = mem::talloc_array(Char16, len + (usz)1);
-	if (!win32::getTempPathW(len, buff)) return io::GENERAL_ERROR?;
-	return path::new(allocator, string::tfrom_utf16(buff[:len]));
+	Char16[] buff = mem::talloc_array(Char16, len);
+	Win32_DWORD res = win32::getTempPathW(len, buff);
+	if (!res) return io::GENERAL_ERROR?;
+	return path::new(allocator, string::tfrom_utf16(buff[:res]));
 }
 
 module std::io::os @if(env::NO_LIBC);

releasenotes.md

@@ -60,6 +60,7 @@
 - bitorder::read and bitorder::write may fail because of unaligned access #2734.
 - Fix `LinkedList.to_format` to properly iterate linked list for printing.
 - Hashing a vector would not use the entire vector in some cases.
+- Fix to `temp_directory` on Windows #2762.
 
 ### Stdlib changes
 - Add `ThreadPool` join function to wait for all threads to finish in the pool without destroying the threads.

test/src/test_suite_runner.c3

@@ -704,11 +704,7 @@ fn int main(String[] args)
 	context.start_cwd = path::tcwd()!!;
 	context.print_mutex.init()!!;
 
-	$if env::WIN32:
-		context.test_root = context.start_cwd;
-	$else
-		context.test_root = path::temp_directory(mem)!!;
-	$endif
+	context.test_root = path::temp_directory(mem)!!;
 
 	Path? path = args[1].to_tpath();
 	if (catch path) arg_error_exit(appname, "Invalid compiler path: %s", args[1]);