[clang-format] Unexpected formatting on function parameter

[LinZhihao-723]

clang-format version: 18.1
Config file: https://github.com/LinZhihao-723/clp/blob/lint-update/components/core/.clang-format
Formatting output: https://github.com/LinZhihao-723/clp/blob/lint-update/components/core/src/clp/ir/LogEventDeserializer.cpp#L13
Formatted result:

template <typename encoded_variable_t>
auto LogEventDeserializer<encoded_variable_t>::create(ReaderInterface& reader
) -> BOOST_OUTCOME_V2_NAMESPACE::std_result<LogEventDeserializer<encoded_variable_t>> {

Expected result:

template <typename encoded_variable_t>
auto LogEventDeserializer<encoded_variable_t>::create(
        ReaderInterface& reader
) -> BOOST_OUTCOME_V2_NAMESPACE::std_result<LogEventDeserializer<encoded_variable_t>> {

Result from clang-format 17:

template <typename encoded_variable_t>
auto LogEventDeserializer<encoded_variable_t>::create(ReaderInterface& reader)
        -> BOOST_OUTCOME_V2_NAMESPACE::std_result<LogEventDeserializer<encoded_variable_t>> {

Not sure if this is a bug or missing configuration in .clang-format. Would be appreciated if someone can help take a look :D

[rymiel]

I bisected this to e00d32a, which is meant to be an NFC commit, which is slightly concerning

Looking at debug output, two lines are different:
The very first token (template) used to be

 M=0 C=0 T=Unknown S=1 F=0 B=0 BK=0 P=0 Name=template L=8 PPK=2 FakeLParens= FakeRParens=0 Text='template'

and now is

 M=0 C=0 T=Unknown S=1 F=0 B=0 BK=0 P=0 Name=template L=8 PPK=2 FakeLParens=1/ FakeRParens=0 Text='template'

the difference being FakeLParens

and the arrow token (->) used to be

 M=0 C=1 T=TrailingReturnArrow S=1 F=0 B=0 BK=0 P=23 Name=arrow L=215 PPK=2 FakeLParens= FakeRParens=0 Text='->'

and is now

 M=0 C=1 T=TrailingReturnArrow S=1 F=0 B=0 BK=0 P=130 Name=arrow L=215 PPK=2 FakeLParens= FakeRParens=0 Text='->'

the difference being the SplitPenalty (P)

[rymiel]

ccae7b4 has changed the output of this to now be:

template <typename encoded_variable_t>
auto LogEventDeserializer<encoded_variable_t>::create(
        ReaderInterface& reader
) -> BOOST_OUTCOME_V2_NAMESPACE::std_result<LogEventDeserializer<encoded_variable_t>> {

..which is exactly what's listed as "expected behavior" in the original bug report