[edk2-devel] [PATCH 1/2] DebugLib: Update DEBUG macro used when MDEPKG_NDEBUG is defined

["Mike Beaton" <mjsbeaton@gmail.com>]

From: Mike Beaton <mjsbeaton@gmail.com>

The variant provided when MDEPKG_NDEBUG is defined will be optimised
away in RELEASE builds, but by referencing the argument list, avoids
unused variable errors from valid debug code, for example when STATIC
variables are used only in DEBUG statements.

Variables EventNames in OvmfPkg/VirtioSerialDxe/VirtioSerial.c
was causing this issue in CLANGPDB X64 RELEASE build, prior to this
commit. It is also necessary to remove manual work-arounds which had
been applied to some similar cases in ArmPkg (see following commit).

Signed-off-by: Mike Beaton <mjsbeaton@gmail.com>
---
 BaseTools/Conf/tools_def.template | 2 +-
 MdePkg/Include/Library/DebugLib.h | 7 ++++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/BaseTools/Conf/tools_def.template b/BaseTools/Conf/tools_def.template
index c34ecfd557..eaccf0b698 100755
--- a/BaseTools/Conf/tools_def.template
+++ b/BaseTools/Conf/tools_def.template
@@ -1859,7 +1859,7 @@ DEFINE CLANGDWARF_X64_DLINK2_FLAGS        = -Wl,--defsym=PECOFF_HEADER_SIZE=0x22
 DEFINE CLANGDWARF_IA32_TARGET             = -target i686-pc-linux-gnu
 DEFINE CLANGDWARF_X64_TARGET              = -target x86_64-pc-linux-gnu
 
-DEFINE CLANGDWARF_WARNING_OVERRIDES    = -Wno-parentheses-equality -Wno-empty-body -Wno-unused-const-variable -Wno-varargs -Wno-unknown-warning-option -Wno-unused-but-set-variable -Wno-unused-const-variable -Wno-unaligned-access -Wno-unneeded-internal-declaration
+DEFINE CLANGDWARF_WARNING_OVERRIDES    = -Wno-parentheses-equality -Wno-empty-body -Wno-unused-const-variable -Wno-varargs -Wno-unknown-warning-option -Wno-unused-but-set-variable -Wno-unused-const-variable -Wno-unaligned-access
 DEFINE CLANGDWARF_ALL_CC_FLAGS         = DEF(GCC48_ALL_CC_FLAGS) DEF(CLANGDWARF_WARNING_OVERRIDES) -fno-stack-protector -mms-bitfields -Wno-address -Wno-shift-negative-value -Wno-unknown-pragmas -Wno-incompatible-library-redeclaration -fno-asynchronous-unwind-tables -mno-sse -mno-mmx -msoft-float -mno-implicit-float  -ftrap-function=undefined_behavior_has_been_optimized_away_by_clang -funsigned-char -fno-ms-extensions -Wno-null-dereference
 
 ###########################
diff --git a/MdePkg/Include/Library/DebugLib.h b/MdePkg/Include/Library/DebugLib.h
index 40772f2e0f..bc7789f01c 100644
--- a/MdePkg/Include/Library/DebugLib.h
+++ b/MdePkg/Include/Library/DebugLib.h
@@ -426,7 +426,12 @@ UnitTestDebugAssert (
       }                            \
     } while (FALSE)
 #else
-#define DEBUG(Expression)
+#define DEBUG(Expression)        \
+    do {                           \
+      if (FALSE) {                 \
+        _DEBUG (Expression);       \
+      }                            \
+    } while (FALSE)
 #endif
 
 /**
-- 
2.39.2



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