[Lldb-commits] [lldb] [LLDB] Update DIL handling of array subscripting. (PR #151605)

[Pavel Labath via lldb-commits]

================
@@ -330,40 +330,83 @@ Interpreter::Visit(const ArraySubscriptNode *node) {
     return lhs_or_err;
   lldb::ValueObjectSP base = *lhs_or_err;
 
-  // Check to see if 'base' has a synthetic value; if so, try using that.
+  StreamString var_expr_path_strm;
   uint64_t child_idx = node->GetIndex();
-  if (lldb::ValueObjectSP synthetic = base->GetSyntheticValue()) {
-    llvm::Expected<uint32_t> num_children =
-        synthetic->GetNumChildren(child_idx + 1);
-    if (!num_children)
-      return llvm::make_error<DILDiagnosticError>(
-          m_expr, toString(num_children.takeError()), node->GetLocation());
-    if (child_idx >= *num_children) {
-      std::string message = llvm::formatv(
+  lldb::ValueObjectSP child_valobj_sp;
+  bool is_incomplete_array = false;
+  CompilerType base_type = base->GetCompilerType().GetNonReferenceType();
+  base->GetExpressionPath(var_expr_path_strm);
+  if (base_type.IsPointerType()) {
+    child_valobj_sp = base->GetSyntheticArrayMember(child_idx, true);
+    if (!child_valobj_sp) {
+      std::string err_msg = llvm::formatv(
+          "failed to use pointer as array for index {0} for "
+          "\"({1}) {2}\"",
+          child_idx, base->GetTypeName().AsCString("<invalid type>"),
+          var_expr_path_strm.GetData());
+      if (base_type.IsPointerToVoid())
+        err_msg = "subscript of pointer to incomplete type 'void'";
+      return llvm::make_error<DILDiagnosticError>(m_expr, std::move(err_msg),
+                                                  node->GetLocation());
+    }
+  } else if (base_type.IsArrayType(nullptr, nullptr, &is_incomplete_array)) {
----------------
labath wrote:

Maybe too fancy, but reduces the scope of the variable.

```suggestion
  } else if (bool is_incomplete_array; base_type.IsArrayType(nullptr, nullptr, &is_incomplete_array)) {
```

https://github.com/llvm/llvm-project/pull/151605