[clang] [clang][clang-scan-deps] Add LangOptions::AllowLiteralDigitSeparator to fix (#88896) (PR #158420)

[Shafik Yaghmour via cfe-commits]

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@@ -1000,6 +1001,21 @@ int z = 128'78;
   EXPECT_STREQ("#include <test.h>\n", Out.data());
 }
 
+TEST(MinimizeSourceToDependencyDirectivesTest, CharacterLiteralInPreprocessor) {
+  SmallVector<char, 128> Out;
+  SmallVector<dependency_directives_scan::Token, 8> Tokens;
+  SmallVector<Directive, 4> Directives;
+
+  StringRef Source = R"(
+    #if 1'2 == 12
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shafik wrote:

I wonder do we have the same problem w/ binary literals which was also brought in via C++14 e.g. `0b10` and then we have the `z` suffix which came in w/ C++23.

https://github.com/llvm/llvm-project/pull/158420