[clang] [clang] Fix potential constant expression checking with constexpr-unknown. (PR #149227)

[Corentin Jabot via cfe-commits]

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@@ -24,3 +24,8 @@ constexpr void other_func() {
 
   throw 12;
 }
+
+// Make sure these don't trigger the diagnostic.
+extern const bool& b;
+constexpr bool fun1() { return b; }
+constexpr bool fun2(const bool& b) { return b; }
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cor3ntin wrote:

Can you reference the issue (either a comment or in the namespace name)?

https://github.com/llvm/llvm-project/pull/149227