Bug 21969 – importC: Error: bit fields are not supported

Bitfields can be supported by merging and replacing them with a representative field - ignoring any field name of the bitfield. --- struct bitfieldsA { int start; unsigned codes : 11; int end; }; struct bitfieldsB { int start; unsigned codes : 11; unsigned reserved : 5; unsigned flags : 16; int end; }; struct bitfieldsC { int start; unsigned codes : 11; unsigned reserved : 5; unsigned : 0; unsigned flags : 16; int end; }; --- The above can be translated into the following D representation without compromising ABI. --- struct bitfieldsA { int start; ushort __bitfield_padding_0; int end; } struct bitfieldsB { int start; uint __bitfield_padding_0; int end; } struct bitfieldsC { int start; ushort __bitfield_padding_0; ushort __bitfield_padding_1; int end; } --- As per the specification: C99 6.7.2.1-11: An implementation may allocate any addressable storage unit large enough to hold a bit-field. If enough space remains, a bit-field that immediately follows another bit-field in a structure shall be packed into adjacent bits of the same unit. If insufficient space remains,whether a bit-field that does not fit is put into the next unit or overlaps adjacent units is implementation-defined. C99 6.7.2.1-12: A bit-field declaration with no declarator, but only a colon and a width, indicates an unnamed bit-field. As a special case, a bit-field structure member with a width of 0 indicates that no further bit-field is to be packed into the unit in which the previous bit-field, if any, was placed.

(In reply to Iain Buclaw from comment #0) > The above can be translated into the following D representation without > compromising ABI. > --- > struct bitfieldsA > { > int start; > ushort __bitfield_padding_0; > int end; > } > If we need to expose the original names of the bit-fields, then @property functions and bitmasks will also suffice.

@ibuclaw created dlang/dmd pull request #12722 "importC: Implement C99 bit-fields - front-end semantic only" mentioning this issue: - partial fix Issue 21969 - importC: Error: bit fields are not supported https://github.com/dlang/dmd/pull/12722

@ibuclaw created dlang/dmd pull request #13033 "fix Issue 21969 - importC: Error: bit fields are not supported" fixing this issue: - fix Issue 21969 - importC: Error: bit fields are not supported https://github.com/dlang/dmd/pull/13033

dlang/dmd pull request #13033 "fix Issue 21969 - importC: Error: bit fields are not supported" was merged into master: - 580a16b91ca1a7dee3d2aa66fd7b11da73b507b5 by Iain Buclaw: fix Issue 21969 - importC: Error: bit fields are not supported https://github.com/dlang/dmd/pull/13033

dlang/dmd pull request #13037 "[stable] Cherry-pick bit-field fixes from master" was merged into stable: - 497464b45bd972426685a33606922dbef3216a52 by Iain Buclaw: fix Issue 21969 - importC: Error: bit fields are not supported https://github.com/dlang/dmd/pull/13037