[clang] Fix printing of templated records. (PR #86339)

[via cfe-commits]

mikaelholmen wrote:

> @zahiraam I still get
> 
> ```
> ../../clang/unittests/AST/DeclPrinterTest.cpp:1394:3: error: expression result unused [-Werror,-Wunused-value]
>   [](PrintingPolicy &Policy) { Policy.SuppressTagKeyword = false; };
>   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../../clang/unittests/AST/DeclPrinterTest.cpp:1405:3: error: expression result unused [-Werror,-Wunused-value]
>   [](PrintingPolicy &Policy) { Policy.SuppressTagKeyword = false; };
>   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../../clang/unittests/AST/DeclPrinterTest.cpp:1416:3: error: expression result unused [-Werror,-Wunused-value]
>   [](PrintingPolicy &Policy) { Policy.SuppressTagKeyword = true; };
>   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../../clang/unittests/AST/DeclPrinterTest.cpp:1435:3: error: expression result unused [-Werror,-Wunused-value]
>   [](PrintingPolicy &Policy) { Policy.SuppressTagKeyword = false; };
>   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../../clang/unittests/AST/DeclPrinterTest.cpp:1455:3: error: expression result unused [-Werror,-Wunused-value]
>   [](PrintingPolicy &Policy) { Policy.SuppressTagKeyword = true; };
>   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 5 errors generated.
> ```
> 
> This has been broken for quite a while now, can you please fix or revert?

Thank you @alinas for fixing the problem in 577e0ef94fb0 !

https://github.com/llvm/llvm-project/pull/86339