More clang-tidy and wjr@ comment fixes

Change-Id: I5736ae482f736fc56c00d21c659b1f8d41da68e9

internal/ceres/autodiff_benchmarks/autodiff_benchmarks.cc

diff --git a/internal/ceres/autodiff_benchmarks/autodiff_benchmarks.cc b/internal/ceres/autodiff_benchmarks/autodiff_benchmarks.cc
index 3d1699b..2ab1598 100644
--- a/internal/ceres/autodiff_benchmarks/autodiff_benchmarks.cc
+++ b/internal/ceres/autodiff_benchmarks/autodiff_benchmarks.cc
@@ -41,7 +41,6 @@
 #include "ceres/ceres.h"
 
 namespace ceres {
-
 namespace internal {
 
 // If we want to use functors with both operator() and an Evaluate() method
@@ -54,7 +53,7 @@
 template <typename CostFunction>
 struct CostFunctionToFunctor {
     template <typename... _Args>
-    CostFunctionToFunctor(_Args&&... __args)
+    explicit CostFunctionToFunctor(_Args&&... __args)
         : cost_function(std::forward<_Args>(__args)...) {}
 
     template <typename... _Args>
@@ -64,7 +63,8 @@
 
     CostFunction cost_function;
 };
-}
+
+}  // namespace internal
 
 template <int kParameterBlockSize>
 static void BM_ConstantAnalytic(benchmark::State& state) {

internal/ceres/problem_test.cc

diff --git a/internal/ceres/problem_test.cc b/internal/ceres/problem_test.cc
index f2b5da5..9093b7a 100644
--- a/internal/ceres/problem_test.cc
+++ b/internal/ceres/problem_test.cc
@@ -2123,16 +2123,12 @@
   EXPECT_EQ(problem.ParameterBlockSize(x), 3);
 }
 
-TEST(Solver, ZeroSizedLocalParameterizationHoldsParameterBlockConstant) {
+TEST(Solver, ZeroSizedLocalParameterizationMeansParameterBlockIsConstant) {
   double x = 0.0;
   double y = 1.0;
   Problem problem;
   problem.AddResidualBlock(new BinaryCostFunction(1, 1, 1), nullptr, &x, &y);
   problem.SetParameterization(&y, new SubsetParameterization(1, {0}));
-  // Zero dimensional tangent space means that the block is
-  // effectively constant, but because the user did not mark it
-  // constant explicitly, the user will not see it as constant when
-  // querying IsParameterBlockConstant.
   EXPECT_TRUE(problem.IsParameterBlockConstant(&y));
 }