[PATCH v1 5/6] perf build: Disable fewer bison warnings

[Ian Rogers <irogers@xxxxxxxxxx>]

If bison is version 3.8.2, reduce the number of bison C warnings
disabled. Earlier bison versions have all C warnings disabled. Avoid
implicit declarations of yylex by adding the declaration in the C
file. A header can't be included as a circular dependency would occur
due to the lexer using the bison defined tokens.

Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
 tools/perf/util/Build          | 6 +++---
 tools/perf/util/bpf-filter.y   | 2 ++
 tools/perf/util/expr.y         | 4 +++-
 tools/perf/util/parse-events.y | 1 +
 tools/perf/util/pmu.y          | 3 +++
 5 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 32239c4b0393..20aa8545b127 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -291,9 +291,9 @@ CFLAGS_expr-flex.o          += $(flex_flags)
 CFLAGS_bpf-filter-flex.o    += $(flex_flags)
 
 bison_flags := -DYYENABLE_NLS=0
-BISON_GE_35 := $(shell expr $(shell $(BISON) --version | grep bison | sed -e 's/.\+ \([0-9]\+\).\([0-9]\+\)/\1\2/g') \>\= 35)
-ifeq ($(BISON_GE_35),1)
-  bison_flags += -Wno-unused-parameter -Wno-nested-externs -Wno-implicit-function-declaration -Wno-switch-enum -Wno-unused-but-set-variable -Wno-unknown-warning-option
+BISON_GE_382 := $(shell expr $(shell $(BISON) --version | grep bison | sed -e 's/.\+ \([0-9]\+\).\([0-9]\+\).\([0-9]\+\)/\1\2\3/g') \>\= 382)
+ifeq ($(BISON_GE_382),1)
+  bison_flags += -Wno-switch-enum
 else
   bison_flags += -w
 endif
diff --git a/tools/perf/util/bpf-filter.y b/tools/perf/util/bpf-filter.y
index 07d6c7926c13..5dfa948fc986 100644
--- a/tools/perf/util/bpf-filter.y
+++ b/tools/perf/util/bpf-filter.y
@@ -9,6 +9,8 @@
 #include <linux/list.h>
 #include "bpf-filter.h"
 
+int perf_bpf_filter_lex(void);
+
 static void perf_bpf_filter_error(struct list_head *expr __maybe_unused,
 				  char const *msg)
 {
diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y
index dd504afd8f36..65d54a6f29ad 100644
--- a/tools/perf/util/expr.y
+++ b/tools/perf/util/expr.y
@@ -7,6 +7,8 @@
 #include "util/debug.h"
 #define IN_EXPR_Y 1
 #include "expr.h"
+#include "expr-bison.h"
+int expr_lex(YYSTYPE * yylval_param , void *yyscanner);
 %}
 
 %define api.pure full
@@ -56,7 +58,7 @@
 static void expr_error(double *final_val __maybe_unused,
 		       struct expr_parse_ctx *ctx __maybe_unused,
 		       bool compute_ids __maybe_unused,
-		       void *scanner,
+		       void *scanner __maybe_unused,
 		       const char *s)
 {
 	pr_debug("%s\n", s);
diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index 454577f7aff6..251b7d2fde32 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -20,6 +20,7 @@
 #include "parse-events.h"
 #include "parse-events-bison.h"
 
+int parse_events_lex(YYSTYPE * yylval_param, YYLTYPE * yylloc_param , void *yyscanner);
 void parse_events_error(YYLTYPE *loc, void *parse_state, void *scanner, char const *msg);
 
 #define PE_ABORT(val) \
diff --git a/tools/perf/util/pmu.y b/tools/perf/util/pmu.y
index dff4e892ac4d..3d46cca3bb94 100644
--- a/tools/perf/util/pmu.y
+++ b/tools/perf/util/pmu.y
@@ -11,6 +11,9 @@
 #include <linux/bitmap.h>
 #include <string.h>
 #include "pmu.h"
+#include "pmu-bison.h"
+
+int perf_pmu_lex(YYSTYPE * yylval_param , void *yyscanner);
 
 #define ABORT_ON(val) \
 do { \
-- 
2.41.0.487.g6d72f3e995-goog