[PATCH] D155064: [clang][SemaCXX] Diagnose tautological uses of consteval if and is_constant_evaluated

[Corentin Jabot via Phabricator via cfe-commits]

cor3ntin added inline comments.


================
Comment at: clang/test/SemaCXX/vartemplate-lambda.cpp:17
+                                                        // expected-note{{cannot be used in a constant expression}} \
+                                                        // expected-error 2{{a lambda expression may not appear inside of a constant expression}}
 };
----------------
This also looks like a regression.

The current error is much clearer, can you investigate?
```
<source>:3:22: error: constexpr variable 't<int>' must be initialized by a constant expression
    3 |   static constexpr T t = [](int f = T(7)){return f;}();
      |                      ^   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:6:12: note: in instantiation of static data member 'S::t<int>' requested here
    6 | int a = S::t<int>;
      |            ^
<source>:3:26: note: non-literal type 'S::(lambda at <source>:3:26)' cannot be used in a constant expression
    3 |   static constexpr T t = [](int f = T(7)){return f;}();
      |                          ^
```

Why do we emt 2 errors instead of a single note? Here the error is that the initializer is not a constant expression, everything else should be notes.


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  https://reviews.llvm.org/D155064/new/

https://reviews.llvm.org/D155064