From a4e22a5df64a46bc99f737a982c0b9d1e8a45e2b Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Wed, 16 Dec 2015 19:25:32 +0000 Subject: [PATCH] [C++] Fix -Winvalid-offsetof warnings with g++ 4.4 MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 ‘size_t VEC_btrace_insn_s_embedded_size(int)’: gdb/btrace.h:84: error: invalid access to non-static data member ‘VEC_btrace_insn_s::vec’ of NULL object gdb/btrace.h:84: error: (perhaps the ‘offsetof’ macro was used incorrectly) gdb/btrace.h: In function ‘VEC_btrace_insn_s* VEC_btrace_insn_s_alloc(int)’: gdb/btrace.h:84: error: invalid access to non-static data member ‘VEC_btrace_insn_s::vec’ of NULL object gdb/btrace.h:84: error: (perhaps the ‘offsetof’ macro was used incorrectly) gdb/btrace.h: In function ‘VEC_btrace_insn_s* VEC_btrace_insn_s_copy(VEC_btrace_insn_s*)’: gdb/btrace.h:84: error: invalid access to non-static data member ‘VEC_btrace_insn_s::vec’ of NULL object gdb/btrace.h:84: error: (perhaps the ‘offsetof’ macro was used incorrectly) gdb/btrace.h: In function ‘VEC_btrace_insn_s* VEC_btrace_insn_s_merge(VEC_btrace_insn_s*, VEC_btrace_insn_s*)’: gdb/btrace.h:84: error: invalid access to non-static data member ‘VEC_btrace_insn_s::vec’ of NULL object gdb/btrace.h:84: error: (perhaps the ‘offsetof’ macro was used incorrectly) gdb/btrace.h: In function ‘int VEC_btrace_insn_s_reserve(VEC_btrace_insn_s**, int, const char*, unsigned int)’: gdb/btrace.h:84: error: invalid access to non-static data member ‘VEC_btrace_insn_s::vec’ of NULL object gdb/btrace.h:84: error: (perhaps the ‘offsetof’ macro was used incorrectly) gdb/ChangeLog: 2015-12-16 Pedro Alves * 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 5eece01721..fcb0e3035f 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,9 @@ +2015-12-16 Pedro Alves + + * 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 * NEWS: Announce fork and exec event support for target remote. diff --git a/gdb/common/vec.h b/gdb/common/vec.h index 6189283a03..a188b02062 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; \ } \ -- 2.34.1