Backport: Implement WStringFromUTF8 to simplify code that creates wstring objects for

regular expressions and calling the Win32 API.

Backport of changeset 7325:6148329fb2f3, but replaced std::string_view usage
with const char* and size_t components. Also used #ifdef instead of C++17
`if constexpr` at suggestion of Neil.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/UniConversion.h b/src/UniConversion.h
index 4bb8875d0..9f405e1ed 100644
--- a/src/UniConversion.h
+++ b/src/UniConversion.h
@@ -19,7 +19,11 @@ void UTF8FromUTF16(const wchar_t *uptr, size_t tlen, char *putf, size_t len);
 void UTF8FromUTF32Character(int uch, char *putf);
 size_t UTF16Length(const char *s, size_t len);
 size_t UTF16FromUTF8(const char *s, size_t len, wchar_t *tbuf, size_t tlen);
+size_t UTF32Length(const char *s, size_t len) noexcept;
 size_t UTF32FromUTF8(const char *s, size_t len, unsigned int *tbuf, size_t tlen);
+// WStringFromUTF8 does the right thing when wchar_t is 2 or 4 bytes so
+// works on both Windows and Unix.
+std::wstring WStringFromUTF8(const char *s, size_t len);
 unsigned int UTF16FromUTF32Character(unsigned int val, wchar_t *tbuf) noexcept;
 bool UTF8IsValid(const char *s, size_t len) noexcept;
 std::string FixInvalidUTF8(const std::string &text);