This is a proposal to resolve bug 741: UefiLib.c compilation failure with clang
error: passing an object that undergoes default argument promotion to
'va_start' has undefined behavior [-Werror,-Wvarargs]"
Rationale:
1. Default argument promotion causes the sizeof a function's argument to be
different than the corresponding
parameter's sizeof. This may break a permissible implemenation of stdarg.h,
which is why it is considered
undefined behavior in C. The condition should be repaired rather than silenced
with -Wno-varargs.
2. The warning is due to the last non-variadic parameter of GetBestLanguage
having type BOOLEAN.
3. BOOLEAN is typedef'd to 'unsigned char' in all ProcessorBind.h.
4. 'unsigned char' goes default argument promotion to int.
5. All ProcessorBind.h typedef the type INT32 to either 'int' or some 32-bit
equivalent.
6. As a result it is safe to replace the type of the parameter from BOOLEAN to
INT32 in all
current supported architectures.
7. The change is consistent with the BOOLEAN argument being converted to INT32
at the caller site. The
function GetBestLanguage currently converts the argument from INT32 back to
BOOLEAN, however
the function's logic is not disturbed by treating the argument as an INT32.
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Zenith432 <zenith...@users.sourceforge.net>
---
MdePkg/Include/Library/UefiLib.h | 2 +-
MdePkg/Library/UefiLib/UefiLib.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/MdePkg/Include/Library/UefiLib.h b/MdePkg/Include/Library/UefiLib.h
index 0b14792a..5d98eb26 100644
--- a/MdePkg/Include/Library/UefiLib.h
+++ b/MdePkg/Include/Library/UefiLib.h
@@ -818,7 +818,7 @@ CHAR8 *
EFIAPI
GetBestLanguage (
IN CONST CHAR8 *SupportedLanguages,
- IN BOOLEAN Iso639Language,
+ IN INT32 Iso639Language,
...
);
diff --git a/MdePkg/Library/UefiLib/UefiLib.c b/MdePkg/Library/UefiLib/UefiLib.c
index a7eee012..57236511 100644
--- a/MdePkg/Library/UefiLib/UefiLib.c
+++ b/MdePkg/Library/UefiLib/UefiLib.c
@@ -1514,7 +1514,7 @@ CHAR8 *
EFIAPI
GetBestLanguage (
IN CONST CHAR8 *SupportedLanguages,
- IN BOOLEAN Iso639Language,
+ IN INT32 Iso639Language,
...
)
{
--
2.14.3 (Apple Git-98)
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