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[pushed] [C++] Fix -Winvalid-offsetof warnings with g++ 4.4
- From: Pedro Alves <palves at redhat dot com>
- To: gdb-patches at sourceware dot org
- Date: Wed, 16 Dec 2015 20:10:14 +0000
- Subject: [pushed] [C++] Fix -Winvalid-offsetof warnings with g++ 4.4
- Authentication-results: sourceware.org; auth=none
Ref: https://sourceware.org/ml/gdb/2015-12/msg00014.html
Fixes the build in C++ mode with g++ 4.4:
gdb/btrace.h: In function âsize_t VEC_btrace_insn_s_embedded_size(int)â:
gdb/btrace.h:84: error: invalid access to non-static data member âVEC_btrace_insn_s::vecâ of NULL object
gdb/btrace.h:84: error: (perhaps the âoffsetofâ macro was used incorrectly)
gdb/btrace.h: In function âVEC_btrace_insn_s* VEC_btrace_insn_s_alloc(int)â:
gdb/btrace.h:84: error: invalid access to non-static data member âVEC_btrace_insn_s::vecâ of NULL object
gdb/btrace.h:84: error: (perhaps the âoffsetofâ macro was used incorrectly)
gdb/btrace.h: In function âVEC_btrace_insn_s* VEC_btrace_insn_s_copy(VEC_btrace_insn_s*)â:
gdb/btrace.h:84: error: invalid access to non-static data member âVEC_btrace_insn_s::vecâ of NULL object
gdb/btrace.h:84: error: (perhaps the âoffsetofâ macro was used incorrectly)
gdb/btrace.h: In function âVEC_btrace_insn_s* VEC_btrace_insn_s_merge(VEC_btrace_insn_s*, VEC_btrace_insn_s*)â:
gdb/btrace.h:84: error: invalid access to non-static data member âVEC_btrace_insn_s::vecâ of NULL object
gdb/btrace.h:84: error: (perhaps the âoffsetofâ macro was used incorrectly)
gdb/btrace.h: In function âint VEC_btrace_insn_s_reserve(VEC_btrace_insn_s**, int, const char*, unsigned int)â:
gdb/btrace.h:84: error: invalid access to non-static data member âVEC_btrace_insn_s::vecâ of NULL object
gdb/btrace.h:84: error: (perhaps the âoffsetofâ macro was used incorrectly)
gdb/ChangeLog:
2015-12-16 Pedro Alves <palves@redhat.com>
* common/vec.h (vec_offset): New macro.
(DEF_VEC_ALLOC_FUNC_I, DEF_VEC_ALLOC_FUNC_O): Use it instead of
offsetof.
---
gdb/ChangeLog | 6 ++++++
gdb/common/vec.h | 44 ++++++++++++++++++++++++++++++++++----------
2 files changed, 40 insertions(+), 10 deletions(-)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 5eece01..fcb0e30 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2015-12-16 Pedro Alves <palves@redhat.com>
+
+ * common/vec.h (vec_offset): New macro.
+ (DEF_VEC_ALLOC_FUNC_I, DEF_VEC_ALLOC_FUNC_O): Use it instead of
+ offsetof.
+
2015-12-11 Don Breazeal <donb@codesourcery.com>
* NEWS: Announce fork and exec event support for target remote.
diff --git a/gdb/common/vec.h b/gdb/common/vec.h
index 6189283..a188b02 100644
--- a/gdb/common/vec.h
+++ b/gdb/common/vec.h
@@ -437,13 +437,23 @@ DEF_VEC_FUNC_O(T) \
DEF_VEC_ALLOC_FUNC_O(T) \
struct vec_swallow_trailing_semi
+/* Avoid offsetof (or its usual C implementation) as it triggers
+ -Winvalid-offsetof warnings with enum_flags types with G++ <= 4.4,
+ even though those types are memcpyable. This requires allocating a
+ dummy local VEC in all routines that use this, but that has the
+ advantage that it only works if T is default constructible, which
+ is exactly a check we want, to keep C compatibility. */
+#define vec_offset(T, VPTR) ((size_t) ((char *) &(VPTR)->vec - (char *) VPTR))
+
#define DEF_VEC_ALLOC_FUNC_I(T) \
static inline VEC(T) *VEC_OP (T,alloc) \
(int alloc_) \
{ \
+ VEC(T) dummy; \
+ \
/* We must request exact size allocation, hence the negation. */ \
return (VEC(T) *) vec_o_reserve (NULL, -alloc_, \
- offsetof (VEC(T),vec), sizeof (T)); \
+ vec_offset (T, &dummy), sizeof (T)); \
} \
\
static inline VEC(T) *VEC_OP (T,copy) (VEC(T) *vec_) \
@@ -453,9 +463,11 @@ static inline VEC(T) *VEC_OP (T,copy) (VEC(T) *vec_) \
\
if (len_) \
{ \
+ VEC(T) dummy; \
+ \
/* We must request exact size allocation, hence the negation. */ \
new_vec_ = (VEC (T) *) \
- vec_o_reserve (NULL, -len_, offsetof (VEC(T),vec), sizeof (T)); \
+ vec_o_reserve (NULL, -len_, vec_offset (T, &dummy), sizeof (T)); \
\
new_vec_->num = len_; \
memcpy (new_vec_->vec, vec_->vec, sizeof (T) * len_); \
@@ -467,12 +479,13 @@ static inline VEC(T) *VEC_OP (T,merge) (VEC(T) *vec1_, VEC(T) *vec2_) \
{ \
if (vec1_ && vec2_) \
{ \
+ VEC(T) dummy; \
size_t len_ = vec1_->num + vec2_->num; \
VEC (T) *new_vec_ = NULL; \
\
/* We must request exact size allocation, hence the negation. */ \
new_vec_ = (VEC (T) *) \
- vec_o_reserve (NULL, -len_, offsetof (VEC(T),vec), sizeof (T)); \
+ vec_o_reserve (NULL, -len_, vec_offset (T, &dummy), sizeof (T)); \
\
new_vec_->num = len_; \
memcpy (new_vec_->vec, vec1_->vec, sizeof (T) * vec1_->num); \
@@ -505,12 +518,13 @@ static inline void VEC_OP (T,cleanup) \
static inline int VEC_OP (T,reserve) \
(VEC(T) **vec_, int alloc_ VEC_ASSERT_DECL) \
{ \
+ VEC(T) dummy; \
int extend = !VEC_OP (T,space) \
(*vec_, alloc_ < 0 ? -alloc_ : alloc_ VEC_ASSERT_PASS); \
\
if (extend) \
*vec_ = (VEC(T) *) vec_o_reserve (*vec_, alloc_, \
- offsetof (VEC(T),vec), sizeof (T)); \
+ vec_offset (T, &dummy), sizeof (T)); \
\
return extend; \
} \
@@ -581,7 +595,9 @@ static inline int VEC_OP (T,iterate) \
static inline size_t VEC_OP (T,embedded_size) \
(int alloc_) \
{ \
- return offsetof (VEC(T),vec) + alloc_ * sizeof(T); \
+ VEC(T) dummy; \
+ \
+ return vec_offset (T, &dummy) + alloc_ * sizeof(T); \
} \
\
static inline void VEC_OP (T,embedded_init) \
@@ -863,7 +879,9 @@ static inline int VEC_OP (T,iterate) \
static inline size_t VEC_OP (T,embedded_size) \
(int alloc_) \
{ \
- return offsetof (VEC(T),vec) + alloc_ * sizeof(T); \
+ VEC(T) dummy; \
+ \
+ return vec_offset (T, &dummy) + alloc_ * sizeof(T); \
} \
\
static inline void VEC_OP (T,embedded_init) \
@@ -998,9 +1016,11 @@ static inline unsigned VEC_OP (T,lower_bound) \
static inline VEC(T) *VEC_OP (T,alloc) \
(int alloc_) \
{ \
+ VEC(T) dummy; \
+ \
/* We must request exact size allocation, hence the negation. */ \
return (VEC(T) *) vec_o_reserve (NULL, -alloc_, \
- offsetof (VEC(T),vec), sizeof (T)); \
+ vec_offset (T, &dummy), sizeof (T)); \
} \
\
static inline VEC(T) *VEC_OP (T,copy) (VEC(T) *vec_) \
@@ -1010,9 +1030,11 @@ static inline VEC(T) *VEC_OP (T,copy) (VEC(T) *vec_) \
\
if (len_) \
{ \
+ VEC(T) dummy; \
+ \
/* We must request exact size allocation, hence the negation. */ \
new_vec_ = (VEC (T) *) \
- vec_o_reserve (NULL, -len_, offsetof (VEC(T),vec), sizeof (T)); \
+ vec_o_reserve (NULL, -len_, vec_offset (T, &dummy), sizeof (T)); \
\
new_vec_->num = len_; \
memcpy (new_vec_->vec, vec_->vec, sizeof (T) * len_); \
@@ -1024,12 +1046,13 @@ static inline VEC(T) *VEC_OP (T,merge) (VEC(T) *vec1_, VEC(T) *vec2_) \
{ \
if (vec1_ && vec2_) \
{ \
+ VEC(T) dummy; \
size_t len_ = vec1_->num + vec2_->num; \
VEC (T) *new_vec_ = NULL; \
\
/* We must request exact size allocation, hence the negation. */ \
new_vec_ = (VEC (T) *) \
- vec_o_reserve (NULL, -len_, offsetof (VEC(T),vec), sizeof (T)); \
+ vec_o_reserve (NULL, -len_, vec_offset (T, &dummy), sizeof (T)); \
\
new_vec_->num = len_; \
memcpy (new_vec_->vec, vec1_->vec, sizeof (T) * vec1_->num); \
@@ -1062,12 +1085,13 @@ static inline void VEC_OP (T,cleanup) \
static inline int VEC_OP (T,reserve) \
(VEC(T) **vec_, int alloc_ VEC_ASSERT_DECL) \
{ \
+ VEC(T) dummy; \
int extend = !VEC_OP (T,space) (*vec_, alloc_ < 0 ? -alloc_ : alloc_ \
VEC_ASSERT_PASS); \
\
if (extend) \
*vec_ = (VEC(T) *) \
- vec_o_reserve (*vec_, alloc_, offsetof (VEC(T),vec), sizeof (T)); \
+ vec_o_reserve (*vec_, alloc_, vec_offset (T, &dummy), sizeof (T)); \
\
return extend; \
} \
--
1.9.3