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[PATCH 2/3 v2] vec: Silence -Wunused-function warnings on clang
- From: Simon Marchi <simon dot marchi at ericsson dot com>
- To: <gdb-patches at sourceware dot org>
- Cc: Pedro Alves <palves at redhat dot com>, Simon Marchi <simon dot marchi at ericsson dot com>
- Date: Mon, 26 Jun 2017 14:45:56 +0200
- Subject: [PATCH 2/3 v2] vec: Silence -Wunused-function warnings on clang
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New in v2:
- Define DIAGNOSTIC_IGNORE_UNUSED_FUNCTION for GCC too.
- Define DIAGNOSTIC_IGNORE_UNUSED_VEC_FUNCTION on clang only and use it.
clang has a too aggressive (or broken, depends on how you want to see
it) -Wunused-function warning, which is triggered by the functions
defined by DEF_VEC_* but not used in the current source file. Normally,
it won't warn about unused static inline functions defined in header
files, because it's expected that a source file won't use all functions
defined in a header file it includes. However, if the DEF_VEC_* macro
is used in a source file, it considers those functions as defined in the
source file, which leads it to think that we should remove those
functions. It is therefore missing a check to see whether those
functions are resulting from macro expansion. A bug already exists for
that:
https://bugs.llvm.org//show_bug.cgi?id=22712
It's quite easy to silence this warning in a localized way, that is in
the DEF_VEC_* macros.
gdb/ChangeLog:
* common/diagnostics.h: Define macros for GCC.
(DIAGNOSTIC_IGNORE_UNUSED_FUNCTION): New macro.
* common/vec.h: Include diagnostics.h.
(DIAGNOSTIC_IGNORE_UNUSED_VEC_FUNCTION): New macro.
(DEF_VEC_I, DEF_VEC_P, DEF_VEC_O): Ignore -Wunused-function
warning.
---
gdb/common/diagnostics.h | 17 +++++++++++++++--
gdb/common/vec.h | 25 +++++++++++++++++++++++++
2 files changed, 40 insertions(+), 2 deletions(-)
diff --git a/gdb/common/diagnostics.h b/gdb/common/diagnostics.h
index 35bacf2..d6ab698 100644
--- a/gdb/common/diagnostics.h
+++ b/gdb/common/diagnostics.h
@@ -31,13 +31,26 @@
# define DIAGNOSTIC_IGNORE(option)
#endif
-#ifdef __clang__
+#if defined (__clang__) /* clang */
+
# define DIAGNOSTIC_IGNORE_SELF_MOVE DIAGNOSTIC_IGNORE ("-Wself-move")
# define DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER \
DIAGNOSTIC_IGNORE ("-Wdeprecated-register")
-#else
+# define DIAGNOSTIC_IGNORE_UNUSED_FUNCTION \
+ DIAGNOSTIC_IGNORE ("-Wunused-function")
+
+#elif defined (__GNUC__) /* GCC */
+
+# define DIAGNOSTIC_IGNORE_SELF_MOVE
+# define DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER
+# define DIAGNOSTIC_IGNORE_UNUSED_FUNCTION \
+ DIAGNOSTIC_IGNORE ("-Wunused-function")
+
+#else /* Other compilers */
+
# define DIAGNOSTIC_IGNORE_SELF_MOVE
# define DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER
+# define DIAGNOSTIC_IGNORE_UNUSED_FUNCTION
#endif
#endif /* COMMON_DIAGNOSTICS_H */
diff --git a/gdb/common/vec.h b/gdb/common/vec.h
index 982f771..98d4576 100644
--- a/gdb/common/vec.h
+++ b/gdb/common/vec.h
@@ -20,6 +20,22 @@
#if !defined (GDB_VEC_H)
#define GDB_VEC_H
+#include "diagnostics.h"
+
+/* clang has a bug that makes it warn (-Wunused-function) about unused functions
+ that are the result of the DEF_VEC_* macro expansion. See:
+
+ https://bugs.llvm.org/show_bug.cgi?id=22712
+
+ We specifically ignore this warning for the vec functions when the compiler
+ is clang. */
+#ifdef __clang__
+# define DIAGNOSTIC_IGNORE_UNUSED_VEC_FUNCTION \
+ DIAGNOSTIC_IGNORE_UNUSED_FUNCTION
+#else
+# define DIAGNOSTIC_IGNORE_UNUSED_VEC_FUNCTION
+#endif
+
/* The macros here implement a set of templated vector types and
associated interfaces. These templates are implemented with
macros, as we're not in C++ land. The interface functions are
@@ -408,6 +424,8 @@ typedef struct VEC(T) \
/* Vector of integer-like object. */
#define DEF_VEC_I(T) \
+DIAGNOSTIC_PUSH \
+DIAGNOSTIC_IGNORE_UNUSED_VEC_FUNCTION \
static inline void VEC_OP (T,must_be_integral_type) (void) \
{ \
(void)~(T)0; \
@@ -416,10 +434,13 @@ static inline void VEC_OP (T,must_be_integral_type) (void) \
VEC_T(T); \
DEF_VEC_FUNC_P(T) \
DEF_VEC_ALLOC_FUNC_I(T) \
+DIAGNOSTIC_POP \
struct vec_swallow_trailing_semi
/* Vector of pointer to object. */
#define DEF_VEC_P(T) \
+DIAGNOSTIC_PUSH \
+DIAGNOSTIC_IGNORE_UNUSED_VEC_FUNCTION \
static inline void VEC_OP (T,must_be_pointer_type) (void) \
{ \
(void)((T)1 == (void *)1); \
@@ -428,13 +449,17 @@ static inline void VEC_OP (T,must_be_pointer_type) (void) \
VEC_T(T); \
DEF_VEC_FUNC_P(T) \
DEF_VEC_ALLOC_FUNC_P(T) \
+DIAGNOSTIC_POP \
struct vec_swallow_trailing_semi
/* Vector of object. */
#define DEF_VEC_O(T) \
+DIAGNOSTIC_PUSH \
+DIAGNOSTIC_IGNORE_UNUSED_VEC_FUNCTION \
VEC_T(T); \
DEF_VEC_FUNC_O(T) \
DEF_VEC_ALLOC_FUNC_O(T) \
+DIAGNOSTIC_POP \
struct vec_swallow_trailing_semi
/* Avoid offsetof (or its usual C implementation) as it triggers
--
2.7.4