Bug 23346 – ImportC: pragma pack is not popped

It seems like #pragma pack(pop) in a C file does not undo a #pragma pack(push). For example (on a target where sizeof(long) == 8): #pragma pack(push, 4) struct Packed { int x; long y; }; #pragma pack(pop) struct NotPacked { int x; // should have 4 bytes of padding long y; }; _Static_assert(sizeof(long)==8, "long is not 8 bytes"); _Static_assert(sizeof(struct Packed)==12, "sizeof(Packed) != 12"); _Static_assert(sizeof(struct NotPacked)==16, "sizeof(NotPacked) != 16”); // This static assertion fails. Compiling with clang passes the static assertions. I noticed this when compiling some code on macOS (which unfortunately uses pragma pack in some system headers).

Inserting #pragma pack(show) into the source makes it obvious that pop is not being applied.

@WalterBright created dlang/dmd pull request #14490 "fix Issue 23346 - ImportC: pragma pack is not popped" fixing this issue: - fix Issue 23346 - ImportC: pragma pack is not popped https://github.com/dlang/dmd/pull/14490