[Lldb-commits] [lldb] [LLDB] Add array subscription and integer parsing to DIL (PR #138551)

[Pavel Labath via lldb-commits]

================
@@ -272,4 +272,67 @@ Interpreter::Visit(const UnaryOpNode *node) {
       m_expr, "invalid ast: unexpected binary operator", node->GetLocation());
 }
 
+llvm::Expected<lldb::ValueObjectSP>
+Interpreter::Visit(const ArraySubscriptNode *node) {
+  auto lhs_or_err = Evaluate(node->GetBase());
+  if (!lhs_or_err) {
+    return lhs_or_err;
+  }
+  lldb::ValueObjectSP base = *lhs_or_err;
+  const llvm::APInt *index = node->GetIndex();
+
+  Status error;
+  if (base->GetCompilerType().IsReferenceType()) {
+    base = base->Dereference(error);
+    if (error.Fail())
+      return error.ToError();
+  }
+
+  // Check to see if 'base' has a synthetic value; if so, try using that.
+  uint64_t child_idx = index->getZExtValue();
+  if (base->HasSyntheticValue()) {
+    lldb::ValueObjectSP synthetic = base->GetSyntheticValue();
+    if (synthetic && synthetic != base) {
+      uint32_t num_children = synthetic->GetNumChildrenIgnoringErrors();
+      // Verify that the 'index' is not out-of-range for the declared type.
+      if (child_idx >= num_children) {
+        auto message = llvm::formatv(
+            "array index {0} is not valid for \"({1}) {2}\"", child_idx,
+            base->GetTypeName().AsCString("<invalid type>"),
+            base->GetName().AsCString());
+        return llvm::make_error<DILDiagnosticError>(m_expr, message,
+                                                    node->GetLocation());
+      }
+
+      if (static_cast<uint32_t>(child_idx) <
+          synthetic->GetNumChildrenIgnoringErrors()) {
+        lldb::ValueObjectSP child_valobj_sp =
+            synthetic->GetChildAtIndex(child_idx);
+        if (child_valobj_sp) {
+          return child_valobj_sp;
+        }
+      }
+    }
+  }
+
+  auto base_type = base->GetCompilerType();
+  if (!base_type.IsPointerType() && !base_type.IsArrayType())
----------------
labath wrote:

This is one of the (few) type checks that I think make sense, but I think this would read better if it was structured like:
```
if (pointer) ...
else if (array) ...
else  /*not pointer or array*/
```

https://github.com/llvm/llvm-project/pull/138551