clang-format cannot format attributes on lambdas

[nico]

Input:

% cat test.cc
void CanonicalCode::write_symbol(LittleEndianOutputBitStream& bit_stream, u32 symbol) const
{
    m_code.visit(
        [&](u32 single_code) __attribute__((always_inline)) -> void {},
        [&](Compress::CanonicalCode const& code) __attribute__((always_inline)) {});
}

clang-format strips the spaces around ->:

% ~/src/llvm-project/out/gn/bin/clang-format test.cc
void CanonicalCode::write_symbol(LittleEndianOutputBitStream& bit_stream, u32 symbol) const
{
    m_code.visit(
        [&](u32 single_code) __attribute__((always_inline))->void {},
        [&](Compress::CanonicalCode const& code) __attribute__((always_inline)) {});
}

This is with today's HEAD (58c7785), but it also repros with older clang-formats.

[llvmbot]

@llvm/issue-subscribers-clang-format

Author: Nico Weber (nico)

Input:

% cat test.cc
void CanonicalCode::write_symbol(LittleEndianOutputBitStream& bit_stream, u32 symbol) const
{
    m_code.visit(
        [&](u32 single_code) __attribute__((always_inline)) -> void {},
        [&](Compress::CanonicalCode const& code) __attribute__((always_inline)) {});
}

clang-format strips the spaces around ->:

% ~/src/llvm-project/out/gn/bin/clang-format test.cc
void CanonicalCode::write_symbol(LittleEndianOutputBitStream& bit_stream, u32 symbol) const
{
    m_code.visit(
        [&](u32 single_code) __attribute__((always_inline))->void {},
        [&](Compress::CanonicalCode const& code) __attribute__((always_inline)) {});
}

This is with today's HEAD (58c7785), but it also repros with older clang-formats.