GeezerVison

Different versions of simdutf may provide different implementations for the same name, for example, the vendored version provides a symbol for simdutf::find(),

simdutf_warn_unused const char *find(const char *start, const char *end,
char character) noexcept;

while upstream simdutf 9.3.3 inlines it,

simdutf_warn_unused simdutf_really_inline simdutf_constexpr23 const char * find(const char *start, const char end, char character) noexcept {
/ An inline function */
...
}

However, the vendored simdutf's headers are currently unconditionally included for merve, regardless whether the shared simdutf is linked against or not, leading to missing symbols at linking time like

mold: error: undefined symbol: simdutf::find(char const*, char const*, char)

referenced by merve.cpp
obj/deps/merve/libmerve.a(obj/deps/merve/merve.merve.o):(lexer::CJSLexer::addReexport(std::__1::basic_string_view<char, std::__1::char_traits>, unsigned int))
referenced by merve.cpp
obj/deps/merve/libmerve.a(obj/deps/merve/merve.merve.o):(lexer::CJSLexer::addExport(std::__1::basic_string_view<char, std::__1::char_traits>, unsigned int))

Do not include the vendored simdutf when compiling merve if shared simdutf is used to ensure the headers match the linked library.