[PATCH v2 07/10] perf parse-events: Disable a subset of flex warnings

[Ian Rogers]

Rather than disable all warnings with -w, disable specific warnings.
Predicate enabling the warnings on more recent flex versions.
Tested with GCC 9.3.0 and clang 9.0.1.

Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
 tools/perf/util/Build | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 504a6bb991ba..53383bd6f4e2 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -221,9 +221,15 @@ $(OUTPUT)util/pmu-bison.c $(OUTPUT)util/pmu-bison.h: util/pmu.y
 	$(Q)$(call echo-cmd,bison)$(BISON) -v $< -d $(PARSER_DEBUG_BISON) \
 		-o $(OUTPUT)util/pmu-bison.c -p perf_pmu_
 
-CFLAGS_parse-events-flex.o  += -w
-CFLAGS_pmu-flex.o           += -w
-CFLAGS_expr-flex.o          += -w
+FLEX_GE_264 := $(shell expr $(shell $(FLEX) --version | sed -e  's/flex \([0-9]\+\).\([0-9]\+\).\([0-9]\+\)/\1\2\3/g') \>\= 264)
+ifeq ($(FLEX_GE_264),1)
+  flex_flags := -Wno-switch-enum -Wno-switch-default -Wno-unused-function -Wno-redundant-decls
+else
+  flex_flags := -w
+endif
+CFLAGS_parse-events-flex.o  += $(flex_flags)
+CFLAGS_pmu-flex.o           += $(flex_flags)
+CFLAGS_expr-flex.o          += $(flex_flags)
 CFLAGS_parse-events-bison.o += -DYYENABLE_NLS=0 -w
 CFLAGS_pmu-bison.o          += -DYYENABLE_NLS=0 -DYYLTYPE_IS_TRIVIAL=0 -w
 CFLAGS_expr-bison.o         += -DYYENABLE_NLS=0 -DYYLTYPE_IS_TRIVIAL=0 -w
-- 
2.27.0.111.gc72c7da667-goog