[Clang] Fix an incorrect assertion in Sema::CheckAddressOfOperand

clang/docs/ReleaseNotes.rst

@@ -379,6 +379,8 @@ Bug Fixes to C++ Support
   the function type.
 - Fix an assertion failure when a ``constexpr`` variable is only referenced through
   ``__builtin_addressof``, and related issues with builtin arguments. (#GH154034)
+- Fix an assertion failure when taking the address on a non-type template parameter argument of
+  object type. (#GH151531)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/Sema/SemaExpr.cpp

@@ -14725,8 +14725,9 @@ QualType Sema::CheckAddressOfOperand(ExprResult &OrigOp, SourceLocation OpLoc) {
           return MPTy;
         }
       }
-    } else if (!isa<FunctionDecl, NonTypeTemplateParmDecl, BindingDecl,
-                    MSGuidDecl, UnnamedGlobalConstantDecl>(dcl))
+    } else if (!isa<FunctionDecl, TemplateParamObjectDecl,
+                    NonTypeTemplateParmDecl, BindingDecl, MSGuidDecl,
+                    UnnamedGlobalConstantDecl>(dcl))
       llvm_unreachable("Unknown/unexpected decl type");
   }
 

clang/test/SemaTemplate/temp_arg_nontype_cxx20.cpp

@@ -371,3 +371,18 @@ namespace ReportedRegression2 {
     fn<str>();
   }
 }
+
+namespace GH151531 {
+struct w {
+    int n;
+};
+
+template <const w *X> void f() { static_assert(X->n == 42); }
+
+template <w X> void g() { f<&X>(); }
+
+void test() {
+    constexpr w X = {42};
+    g<X>();
+}
+}