..I just realised that the clang flag is -Wbitfield-enum-conversion, not
-Wenum-bitfield-conversion. Please apply the patch below instead, which
has replaced the two words to remove the inconsistency.
2017-10-16 Sam van Kampen <sam@segfault.party>
* c-family/c.opt: Add a warning flag for struct bit-fields
being too small to hold enumerated types.
* cp/class.c: Likewise.
* doc/invoke.texi: Add documentation for said warning flag.
Index: gcc/c-family/c.opt
===================================================================
--- gcc/c-family/c.opt (revision 253784)
+++ gcc/c-family/c.opt (working copy)
@@ -346,6 +346,10 @@ Wframe-address
C ObjC C++ ObjC++ Var(warn_frame_address) Warning LangEnabledBy(C ObjC C++
ObjC++,Wall)
Warn when __builtin_frame_address or __builtin_return_address is used unsafely.
+Wbitfield-enum-conversion
+C++ Var(warn_bitfield_enum_conversion) Init(1) Warning
+Warn about struct bit-fields being too small to hold enumerated types.
+
Wbuiltin-declaration-mismatch
C ObjC C++ ObjC++ Var(warn_builtin_declaraion_mismatch) Init(1) Warning
Warn when a built-in function is declared with the wrong signature.
Index: gcc/cp/class.c
===================================================================
--- gcc/cp/class.c (revision 253784)
+++ gcc/cp/class.c (working copy)
@@ -3278,10 +3278,11 @@ check_bitfield_decl (tree field)
&& tree_int_cst_lt (TYPE_SIZE (type), w)))
warning_at (DECL_SOURCE_LOCATION (field), 0,
"width of %qD exceeds its type", field);
- else if (TREE_CODE (type) == ENUMERAL_TYPE
+ else if (warn_bitfield_enum_conversion
+ && TREE_CODE (type) == ENUMERAL_TYPE
&& (0 > (compare_tree_int
(w, TYPE_PRECISION (ENUM_UNDERLYING_TYPE (type))))))
- warning_at (DECL_SOURCE_LOCATION (field), 0,
+ warning_at (DECL_SOURCE_LOCATION (field), OPT_Wbitfield_enum_conversion,
"%qD is too small to hold all values of %q#T",
field, type);
}
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi (revision 253784)
+++ gcc/doc/invoke.texi (working copy)
@@ -264,7 +264,7 @@ Objective-C and Objective-C++ Dialects}.
-Walloca -Walloca-larger-than=@var{n} @gol
-Wno-aggressive-loop-optimizations -Warray-bounds -Warray-bounds=@var{n} @gol
-Wno-attributes -Wbool-compare -Wbool-operation @gol
--Wno-builtin-declaration-mismatch @gol
+-Wbitfield-enum-conversion -Wno-builtin-declaration-mismatch @gol
-Wno-builtin-macro-redefined -Wc90-c99-compat -Wc99-c11-compat @gol
-Wc++-compat -Wc++11-compat -Wc++14-compat @gol
-Wcast-align -Wcast-align=strict -Wcast-qual @gol
@@ -5431,6 +5431,12 @@ Incrementing a boolean is invalid in C++17, and de
This warning is enabled by @option{-Wall}.
+@item -Wbitfield-enum-conversion
+@opindex Wbitfield-enum-conversion
+@opindex Wno-bitfield-enum-conversion
+Warn about a bit-field potentially being too small to hold all values
+of an enumerated type. This warning is enabled by default.
+
@item -Wduplicated-branches
@opindex Wno-duplicated-branches
@opindex Wduplicated-branches
