[clang] [Clang][Sema] Print more static_assert exprs (PR #74852)

[Erich Keane via cfe-commits]

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@@ -0,0 +1,117 @@
+// RUN: %clang_cc1 -std=c++2a -verify %s
+
+struct A {
+  int a, b[3], c;
+  bool operator==(const A&) const = default;
+};
+
+constexpr auto a0 = A{0, 0, 3, 4, 5};
+
+// expected-note at +1 {{evaluates to '{0, {0, 3, 4}, 5} == {1, {2, 3, 4}, 5}'}}
+static_assert(a0 == A{1, {2, 3, 4}, 5}); // expected-error {{failed}}
+
+struct _arr {
+  const int b[3];
+  constexpr bool operator==(const int rhs[3]) const {
+    for (unsigned i = 0; i < sizeof(b) / sizeof(int); i++)
+      if (b[i] != rhs[i])
+        return false;
+    return true;
+  }
+};
+
+// TODO[seth] syntactically sort of valid but almost entirely unusuable
+// (it's an int *, not an int [3] )
+// constexpr int _[3] = {...}; would work, but that's not piecewise substitutable
+// maybe it's ok? I mean, not like we can do better really...
+constexpr auto _ = (int[3]){2, 3, 4};
+
+// output: '{{2, 3, 4}} == {0, 3, 4}'  (the `{{` breaks VerifyDiagnosticConsumer::ParseDirective)
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erichkeane wrote:

IIRC, you can escape a { with \.

https://github.com/llvm/llvm-project/pull/74852