Upgrade frontend & libs to v2.110

[kinke]

No description provided.

[kinke]

Great, just one problem for new runnable_cxx/testbitfields.d, possibly the same as #4646.

[kinke]

Interesting, another bit fields problem remaining, on Linux AArch64 only, working with Apple-clang on arm64 though; probably a frontend problem, needing more special cases:

1837: Test 'runnable_cxx/testbitfields.d' failed. The logged output:
1837: /tmp/cirrus-ci-build/../clang/bin/clang++ -c runnable_cxx/extra-files/testbitfields_cpp.cpp -o ../../../build/dmd-testsuite-debug/runnable_cxx/d/testbitfields_cpp.cpp.o -std=c++11
1837: /tmp/build/bin/ldmd2 -conf= -m64 -Irunnable_cxx -g -link-defaultlib-debug -L-lstdc++ -L--no-demangle  -od../../../build/dmd-testsuite-debug/runnable_cxx/d -of../../../build/dmd-testsuite-debug/runnable_cxx/d/testbitfields_0  runnable_cxx/testbitfields.d runnable_cxx/extra-files/testbitfields_importc.c ../../../build/dmd-testsuite-debug/runnable_cxx/d/testbitfields_cpp.cpp.o 
1837: ../../../build/dmd-testsuite-debug/runnable_cxx/d/testbitfields_0  --DRT-testmode=run-main
1837: Struct S16 has different bitfield layout for C and D:
1837:   D: size=4 align=1
1837:   C: size=4 align=4
1837: Struct S18 has different bitfield layout for C and D:
1837:   D: size=9 align=1
1837:   C: size=16 align=8
1837:   char a:
1837:     D: FF000000 00000000 00
1837:     C: FF000000 00000000 00000000 00000000
1837:   char b:
1837:     D: 00000000 00000000 FF
1837:     C: 00000000 00000000 FF000000 00000000

[kinke]

Oh WTF:

struct S16 { int :32; };
struct S18 { char a; long long :0; char b; };

static_assert(alignof(S16) == 1); // 4 on non-Apple AArch64
static_assert(alignof(S18) == 1); // 8 on non-Apple AArch64

It works fine for arm64-apple-macos and riscv64-linux-gnu, x86 etc., but not for aarch64-linux-gnu and aarch64-freebsd. So looks like some AArch64 special case, where anonymous and 0-length bitfields do contribute to the aggregate alignment, and Apple went with a simpler/standard approach. I've checked this with clang v18.1.0, and latest stable AArch64 gcc on godbolt.org.

This appears to be handled in https://github.com/dlang/dmd/blob/6c826179ad5eec50b0bc40411acce8f7053e333f/compiler/src/dmd/dsymbolsem.d#L7176-L7193, possibly requiring a new BitFieldStyle enum member.

[kinke]

Okay, spec is here: https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst#1018bit-fields

The container type contributes to the alignment of the containing aggregate in the same way a plain (not bit-field) member of that type would, without exception for zero-sized or anonymous bit-fields.

Note

The C++ standard states that an anonymous bit-field is not a member, so it is unclear whether or not an anonymous bit-field of non-zero size should contribute to an aggregate’s alignment. Under this ABI it does.

[tim-dlang]

The layout for Linux armv7 is currently also wrong. Interestingly Apple seems to behave the same as Linux for armv7 and only aarch64 is different:

for t in aarch64-apple-darwin aarch64-unknown-linux-gnu \
  armv7k-apple-watchos armv7s-apple-ios armv7-unknown-linux-gnueabi
do
  echo ============ $t ============
  clang test.c -Xclang -fdump-record-layouts -c --target="$t" \
    | sed -n "/Dumping AST/,/^$/p"
done

============ aarch64-apple-darwin ============
*** Dumping AST Record Layout
         0 | struct S18
         0 |   char a
       8:- |   long long 
         8 |   char b
           | [sizeof=9, align=1]

============ aarch64-unknown-linux-gnu ============
*** Dumping AST Record Layout
         0 | struct S18
         0 |   char a
       8:- |   long long 
         8 |   char b
           | [sizeof=16, align=8]

============ armv7k-apple-watchos ============
*** Dumping AST Record Layout
         0 | struct S18
         0 |   char a
       8:- |   long long 
         8 |   char b
           | [sizeof=16, align=8]

============ armv7s-apple-ios ============
*** Dumping AST Record Layout
         0 | struct S18
         0 |   char a
       4:- |   long long 
         4 |   char b
           | [sizeof=8, align=4]

============ armv7-unknown-linux-gnueabi ============
*** Dumping AST Record Layout
         0 | struct S18
         0 |   char a
       8:- |   long long 
         8 |   char b
           | [sizeof=16, align=8]