Add Crystal::System.wstr_literal on Windows

spec/support/time.cr

@@ -66,9 +66,9 @@ end
     fun SetDynamicTimeZoneInformation(lpTimeZoneInformation : DYNAMIC_TIME_ZONE_INFORMATION*) : BOOL
   end
 
-  private SeTimeZonePrivilege = Crystal::System.to_wstr("SeTimeZonePrivilege")
-
   module Crystal::System::Time
+    private SeTimeZonePrivilege = System.wstr_literal "SeTimeZonePrivilege"
+
     # Enable the `SeTimeZonePrivilege` privilege before changing the system time
     # zone. This is necessary because the privilege is by default granted but
     # disabled for any new process. This only needs to be done once per run.

src/crystal/system/win32/mime.cr

@@ -1,7 +1,7 @@
 require "./windows_registry"
 
 module Crystal::System::MIME
-  CONTENT_TYPE = "Content Type".to_utf16
+  CONTENT_TYPE = System.wstr_literal "Content Type"
 
   # Load MIME types from operating system source.
   def self.load

src/crystal/system/win32/time.cr

@@ -192,10 +192,10 @@ module Crystal::System::Time
     return stdname, dstname
   end
 
-  REGISTRY_TIME_ZONES = %q(SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones).to_utf16
-  Std                 = "Std".to_utf16
-  Dlt                 = "Dlt".to_utf16
-  TZI                 = "TZI".to_utf16
+  REGISTRY_TIME_ZONES = System.wstr_literal %q(SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones)
+  Std                 = System.wstr_literal "Std"
+  Dlt                 = System.wstr_literal "Dlt"
+  TZI                 = System.wstr_literal "TZI"
 
   # Searches the registry for an English name of a time zone named *stdname* or *dstname*
   # and returns the English name.

src/crystal/system/win32/user.cr

@@ -172,8 +172,8 @@ module Crystal::System::User
     end
   end
 
-  private REGISTRY_PROFILE_LIST = %q(SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList).to_utf16
-  private ProfileImagePath      = "ProfileImagePath".to_utf16
+  private REGISTRY_PROFILE_LIST = System.wstr_literal %q(SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList)
+  private ProfileImagePath      = System.wstr_literal "ProfileImagePath"
 
   private def self.lookup_home_directory(uid : String, username : String) : String?
     # If this user has logged in at least once their home path should be stored

src/crystal/system/win32/windows_sdk.cr

@@ -1,11 +1,11 @@
 require "./windows_registry"
 
 module Crystal::System::WindowsSDK
-  REGISTRY_WIN10_SDK_64 = %q(SOFTWARE\WOW6432Node\Microsoft\Microsoft SDKs\Windows\v10.0).to_utf16
-  REGISTRY_WIN10_SDK_32 = %q(SOFTWARE\Microsoft\Microsoft SDKs\Windows\v10.0).to_utf16
+  REGISTRY_WIN10_SDK_64 = System.wstr_literal %q(SOFTWARE\WOW6432Node\Microsoft\Microsoft SDKs\Windows\v10.0)
+  REGISTRY_WIN10_SDK_32 = System.wstr_literal %q(SOFTWARE\Microsoft\Microsoft SDKs\Windows\v10.0)
 
-  InstallationFolder = "InstallationFolder".to_utf16
-  ProductVersion     = "ProductVersion".to_utf16
+  InstallationFolder = System.wstr_literal "InstallationFolder"
+  ProductVersion     = System.wstr_literal "ProductVersion"
 
   def self.find_win10_sdk_libpath : ::Path?
     # ported from Common7\Tools\vsdevcmd\core\winsdk.bat (loaded by the MSVC

src/crystal/system/windows.cr

@@ -16,6 +16,22 @@ module Crystal::System
     str.check_no_null_byte(name).to_utf16.to_unsafe
   end
 
+  # Converts the string literal *str* into a `Slice` of UTF-16 code points.
+  # *str* must not contain embedded null characters.
+  #
+  # This is equivalent to the macro `StringLiteral#to_utf16` if slice literals
+  # are available, and the normal `String#to_utf16` otherwise. This is useful
+  # for passing constant string arguments to Win32 functions.
+  {% if compare_versions(Crystal::VERSION, "1.16.0") >= 0 %}
+    macro wstr_literal(str)
+      \{{ str.to_utf16 }}
+    end
+  {% else %}
+    macro wstr_literal(str)
+      (\{{ str }}).check_no_null_byte.to_utf16
+    end
+  {% end %}
+
   def self.sid_to_s(sid : LibC::SID*) : String
     if LibC.ConvertSidToStringSidW(sid, out ptr) == 0
       raise RuntimeError.from_winerror("ConvertSidToStringSidW")

src/crystal/tracing.cr

@@ -147,6 +147,7 @@ module Crystal
         {% if flag?(:win32) %}
           buf = uninitialized UInt16[256]
 
+          # FIXME: use `System.wstr_literal` after #15746 is available
           name = UInt16.static_array({% for chr in "CRYSTAL_TRACE".chars %}{{chr.ord}}, {% end %} 0)
           len = LibC.GetEnvironmentVariableW(name, buf, buf.size)
           parse_sections(buf.to_slice[0...len]) if len > 0