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

[via cfe-commits]

================
@@ -17256,6 +17378,56 @@ static bool ConvertAPValueToString(const APValue &V, QualType T,
     OS << "i)";
   } break;
 
+  case APValue::ValueKind::Array:
+  case APValue::ValueKind::Vector: {
+    llvm::raw_svector_ostream OS(Str);
+    // we hope to emit a valid initalizer expression
+    // like `(const int[3]){1, 2, 3}`
+    OS << '(' << T << ')';
+    PrintingPolicy Policy(Context.getPrintingPolicy());
+    Policy.UseEnumerators = true;
+    unsigned Limit = Context.getDiagnostics().getConstexprValueSizeLimit();
+    if (Limit) {
+      size_limited_ostream OSS(OS, Limit);
+      V.printPretty(OSS, Policy, T, &Context);
+    } else
+      V.printPretty(OS, Policy, T, &Context);
+  } break;
+
+  case APValue::ValueKind::Struct: {
+    llvm::raw_svector_ostream OS(Str);
+    const auto *RT = T->getAsStructureType();
+    if (RT->hasUnnamedOrLocalType()) {
+      OS << '(';
+      // e.g. `(unnamed struct at ...)`, unless...
+      if (const auto *Defn = RT->getDecl()->getDefinition()) {
+        if (const NamedDecl *ND =
+                dyn_cast_if_present<NamedDecl>(Defn->getNextDeclInContext())) {
+          // ... it's part of a declaration,  then use `(decltype(...))`
+          OS << "decltype(";
+          ND->printQualifiedName(OS);
+          OS << ")";
+        } else
+          Defn->printQualifiedName(OS);
+      }
+      OS << ')';
+    } else if (T.hasQualifiers()) {
+      OS << '(' << T << ')';
+    } else {
+      PrintingPolicy TyPolicy(Context.getPrintingPolicy());
+      TyPolicy.SuppressUnwrittenScope = true;
+      T.print(OS, TyPolicy);
+    }
----------------
cor3ntin wrote:

Why are these two cases so different?

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