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Michael Kubacki 7a934d0bef MdeModulePkg: Replace include guards with #pragma once
Replace traditional `#ifndef`/`#define`/`#endif` include guards with
`#pragma` once.

`#pragma once` is a widely supported preprocessor directive that
prevents header files from being included multiple times. It is
supported by all toolchains used to build edk2: GCC, Clang/LLVM, and
MSVC.

Compared to macro-based include guards, `#pragma once`:

- Eliminates the risk of macro name collisions or copy/paste errors
  where two headers inadvertently use the same guard macro.
- Eliminate inconsistency in the way include guard macros are named
  (e.g., some files use `__FILE_H__`, others use `FILE_H_`, etc.).
- Reduces boilerplate (three lines replaced by one).
- Avoids polluting the macro namespace with guard symbols.
- Can improve build times as the preprocessor can skip re-opening the
  file entirely, rather than re-reading it to find the matching
  `#endif` ("multiple-include optimization").
  - Note that some compilers may already optimize traditional include
    guards, by recognzining the idiomatic pattern.

This change is made acknowledging that overall portability of the
code will technically be reduced, as `#pragma once` is not part of the
C/C++ standards.

However, this is considered acceptable given:

1. edk2 already defines a subset of supported compilers in
   BaseTools/Conf/tools_def.template, all of which have supported
   `#pragma once` for over two decades.
2. There have been concerns raised to the project about inconsistent
   include guard naming and potential macro collisions.

Approximate compiler support dates:

- MSVC: Supported since Visual C++ 4.2 (1996)
- GCC: Supported since 3.4 (2004)
  (http://gnu.ist.utl.pt/software/gcc/gcc-3.4/changes.html)
- Clang (LLVM based): Since initial release in 2007

Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
2026-02-23 21:01:28 +00:00

27 lines
878 B
C

/** @file
Formset guids, form id and VarStore data structure for File explorer library.
Copyright (c) 2004 - 2017, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#pragma once
#define EFI_FILE_EXPLORE_FORMSET_GUID \
{ \
0xfe561596, 0xe6bf, 0x41a6, {0x83, 0x76, 0xc7, 0x2b, 0x71, 0x98, 0x74, 0xd0} \
}
#define FORM_FILE_EXPLORER_ID 0x1000
#define FORM_ADD_NEW_FILE_ID 0x2000
#define NEW_FILE_NAME_ID 0x2001
#define KEY_VALUE_CREATE_FILE_AND_EXIT 0x2002
#define KEY_VALUE_NO_CREATE_FILE_AND_EXIT 0x2003
#define FORM_ADD_NEW_FOLDER_ID 0x3000
#define NEW_FOLDER_NAME_ID 0x3001
#define KEY_VALUE_CREATE_FOLDER_AND_EXIT 0x3002
#define KEY_VALUE_NO_CREATE_FOLDER_AND_EXIT 0x3003
#define LABEL_END 0xffff