[clang] [Clang][Preprocessor] Unify header-name lookahead for import and include (PR #191004)

[Jordan Rose via cfe-commits]

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@@ -422,6 +422,7 @@ Bug Fixes in This Version
 - Fixed a crash on _BitInt(N) arrays where 129 ≤ N ≤ 192 due to incorrect array filler lowering. (#GH189643)
 - Fixed the behavior in C23 of ``auto``, by emitting an error when an array type is specified for a ``char *``. (#GH162694)
 - Fixed incorrect rejection of ``auto`` with reordered declaration specifiers in C23. (#GH164121)
+- Fixed incorrect handling of header-name lookahead in C++ import and #include directives involving digraphs and macro expansion. (#GH190693)
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belkadan wrote:

Belated: I'm not an *active* hobbyist, but while `:Macintosh HD:CIncludes:header.h` would be a valid absolute path on classic Mac OS, neither I nor Gwynne Raskind could think of a reason someone would specify a header path that way, and if they really needed to they could presumably use quotes instead of angle brackets. (None of the platform headers I have on hand do such a thing.)

https://github.com/llvm/llvm-project/pull/191004