[PATCH bpf-next v2 1/2] bpftool: Add -Wformat-signedness flag to detect format errors

[Jiayuan Chen <jiayuan.chen@linux.dev>]

This commit adds the -Wformat-signedness compiler flag to detect and
prevent printf format errors, where signed or unsigned types are
mismatched with format specifiers. This helps to catch potential issues at
compile-time, ensuring that our code is more robust and reliable. With
this flag, the compiler will now warn about incorrect format strings, such
as using %d with unsigned types or %u with signed types.

Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
---
 tools/bpf/bpftool/Makefile | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index dd9f3ec84201..efe867dd2821 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -71,7 +71,12 @@ prefix ?= /usr/local
 bash_compdir ?= /usr/share/bash-completion/completions
 
 CFLAGS += -O2
-CFLAGS += -W -Wall -Wextra -Wno-unused-parameter -Wno-missing-field-initializers
+CFLAGS += -W
+CFLAGS += -Wall
+CFLAGS += -Wextra
+CFLAGS += -Wformat-signedness
+CFLAGS += -Wno-unused-parameter
+CFLAGS += -Wno-missing-field-initializers
 CFLAGS += $(filter-out -Wswitch-enum -Wnested-externs,$(EXTRA_WARNINGS))
 CFLAGS += -DPACKAGE='"bpftool"' -D__EXPORTED_HEADERS__ \
 	-I$(or $(OUTPUT),.) \
-- 
2.47.1