[clang] [Clang] Ignore -fchar8_t in C (PR #138716)

[Aaron Ballman via cfe-commits]

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@@ -5,6 +5,7 @@
 // RUN: %clang_cc1 -std=c++17 -verify %s
 // RUN: %clang_cc1 -std=c++17 -verify %s -fno-char8_t
 // RUN: %clang_cc1 -std=c++20 -verify %s -fno-char8_t
+// RUN: %clang_cc1 -x c -verify %s -fchar8_t
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AaronBallman wrote:

Shouldn't this generate a diagnostic now? Or are we planning to continue to accept in cc1 mode? If so, we need a driver test showing we reject from the driver side.

https://github.com/llvm/llvm-project/pull/138716