[clangd] Add metrics for recovery-expr type propagation.

clang-tools-extra/clangd/Selection.cpp

 namespace {
 using Node = SelectionTree::Node;
 using ast_type_traits::DynTypedNode;
 
 // Measure the fraction of selections that were enabled by recovery AST.
 void recordMetrics(const SelectionTree &S) {
   static constexpr trace::Metric SelectionUsedRecovery(
       "selection_recovery", trace::Metric::Distribution);
+  static constexpr trace::Metric RecoveryType("selection_recovery_type",
+                                              trace::Metric::Distribution);
   const auto *Common = S.commonAncestor();
   for (const auto *N = Common; N; N = N->Parent) {
-    if (N->ASTNode.get<RecoveryExpr>()) {
+    if (const auto *RE = N->ASTNode.get<RecoveryExpr>()) {
       SelectionUsedRecovery.record(1); // used recovery ast.
+      RecoveryType.record(RE->isTypeDependent() ? 0 : 1);
       return;
     }
   }
   if (Common)
     SelectionUsedRecovery.record(0); // unused.
 }
 
 // An IntervalSet maintains a set of disjoint subranges of an array.

clang-tools-extra/clangd/unittests/SelectionTests.cpp

const char *Code = R"cpp(
     int foo(int, int);
     int x = fo^o(42);
   )cpp";
   auto AST = TestTU::withCode(Annotations(Code).code()).build();
   trace::TestTracer Tracer;
   auto T = makeSelectionTree(Code, AST);
   EXPECT_THAT(Tracer.takeMetric("selection_recovery"),
               testing::ElementsAreArray({1}));
+  EXPECT_THAT(Tracer.takeMetric("selection_recovery_type"),
+              testing::ElementsAreArray({1}));
 }
 
 // FIXME: Doesn't select the binary operator node in
 //          #define FOO(X) X + 1
 //          int a, b = [[FOO(a)]];
 TEST(SelectionTest, Selected) {
   // Selection with ^marks^.
   // Partially selected nodes marked with a [[range]].