Clang build fixes (#15628)

* Remove some superfluous std::move calls

The std:move triggered a build error (with -Werror):
```
[  9%] Building CXX object paddle/fluid/memory/allocation/CMakeFiles/allocator_facade.dir/allocator_facade.cc.o
/home/tej/code/gbuella_paddle/paddle/fluid/memory/allocation/allocator_facade.cc:86:29: error: moving a temporary object prevents copy elision [-Werror,-Wpessimizing-move]
            [this] { return std::move(CreateAllocatorWithChunk()); }, capacity);
                            ^
/home/tej/code/gbuella_paddle/paddle/fluid/memory/allocation/allocator_facade.cc:86:29: note: remove std::move call here
            [this] { return std::move(CreateAllocatorWithChunk()); }, capacity);
                            ^~~~~~~~~~                          ~
1 error generated.
```

See: https://reviews.llvm.org/D7633

* Remove a superfluous lambda capture from framework/operator.h

```
[ 10%] Building CXX object paddle/fluid/platform/CMakeFiles/device_context.dir/init.cc.o
In file included from /home/tej/code/gbuella_paddle/paddle/fluid/platform/init.cc:19:
/home/tej/code/gbuella_paddle/paddle/fluid/framework/operator.h:229:21: error: lambda capture 'this' is not used [-Werror,-Wunused-lambda-capture]
                   [this](Variable* var) { return var; });
                    ^~~~
1 error generated.
```

Changing it to `return it->second;`, as is in the function below.

* Rethrow an exception (instead of copying it)

```
[ 11%] Building CXX object paddle/fluid/framework/CMakeFiles/operator.dir/operator.cc.o
/home/tej/code/gbuella_paddle/paddle/fluid/framework/operator.cc:191:13: error: local variable 'exception' will be copied despite being thrown by name [-Werror,-Wreturn-std-move]
      throw exception;
            ^~~~~~~~~
/home/tej/code/gbuella_paddle/paddle/fluid/framework/operator.cc:191:13: note: call 'std::move' explicitly to avoid copying
      throw exception;
            ^~~~~~~~~
            std::move(exception)

```

See https://reviews.llvm.org/D43322 for an explanation of this diagnostic message.

* Remove an unused variable

```
/home/tej/code/gbuella_paddle/paddle/fluid/framework/operator.cc:884:16: error: private field 'scope_' is not used [-Werror,-Wunused-private-field]
  const Scope& scope_;
               ^
```

* struct ComputationOpHandle -> class ComputationOpHandle

```
[ 13%] Building CXX object paddle/fluid/framework/details/CMakeFiles/memory_early_delete_pass.dir/memory_early_delete_pass.cc.o
In file included from /home/tej/code/gbuella_paddle/paddle/fluid/framework/details/memory_early_delete_pass.cc:21:
/home/tej/code/gbuella_paddle/paddle/fluid/framework/details/reference_count_pass_helper.h:30:1: error: class 'ComputationOpHandle' was previously declared as a struct; this is valid, but may result in linker errors under the Microsoft C++ ABI [-Werror,-Wmismatched-tags]
class ComputationOpHandle;
^
/home/tej/code/gbuella_paddle/paddle/fluid/framework/details/computation_op_handle.h:29:8: note: previous use is here
struct ComputationOpHandle : public OpHandleBase {
       ^
/home/tej/code/gbuella_paddle/paddle/fluid/framework/details/reference_count_pass_helper.h:30:1: note: did you mean struct here?
class ComputationOpHandle;
^~~~~
struct
1 error generated.
```

* Fix name() methods under fluid/operators

```
In file included from /home/tej/code/gbuella_paddle/paddle/fluid/operators/jit/gen/act.cc:15:
In file included from /home/tej/code/gbuella_paddle/paddle/fluid/operators/jit/gen/act.h:19:
/home/tej/code/gbuella_paddle/paddle/fluid/operators/jit/gen/jitcode.h:71:23: error: 'name' overrides a member function but is not marked 'override' [-Werror,-Winconsistent-missing-override]
  virtual const char* name() const = 0;
                      ^
/home/tej/code/gbuella_paddle/paddle/fluid/operators/jit/gen_base.h:31:23: note: overridden virtual function is here
  virtual const char* name() const = 0;
                      ^
```

test=develop

paddle/fluid/framework/details/computation_op_handle.h

@@ -26,7 +26,7 @@
 namespace paddle {
 namespace framework {
 namespace details {
-struct ComputationOpHandle : public OpHandleBase {
+class ComputationOpHandle : public OpHandleBase {
  public:
   ComputationOpHandle(ir::Node *node, Scope *scope, platform::Place place,
                       size_t scope_idx);

paddle/fluid/framework/details/parallel_ssa_graph_executor.cc

@@ -65,7 +65,7 @@ FeedFetchList ParallelSSAGraphExecutor::Run(
     if (pool_) {
       run_futures.emplace_back(pool_->enqueue(std::move(call)));
     } else {
-      fetch_data.emplace_back(std::move(call()));
+      fetch_data.emplace_back(call());
     }
   }
 
@@ -74,7 +74,7 @@ FeedFetchList ParallelSSAGraphExecutor::Run(
       if (exception_holder_.IsCaught()) {
         f.wait();
       } else {
-        fetch_data.emplace_back(std::move(f.get()));
+        fetch_data.emplace_back(f.get());
       }
     }
   }

paddle/fluid/framework/ir/graph.cc

@@ -76,7 +76,7 @@ std::map<std::string, std::vector<ir::Node *>> Graph::InitFromProgram(
       var->inputs.push_back(node);
     }
   }
-  return std::move(var_nodes);
+  return var_nodes;
 }
 
 void Graph::ResolveHazard(

paddle/fluid/framework/operator.cc

@@ -188,14 +188,14 @@ void OperatorBase::Run(const Scope& scope, const platform::Place& place) {
     VLOG(3) << place << " " << DebugStringEx(&scope);
   } catch (platform::EnforceNotMet exception) {
     if (Attrs().count("sub_block") != 0) {
-      throw exception;
+      throw;
     }
 
     auto& callstack = Attr<std::vector<std::string>>(
         OpProtoAndCheckerMaker::OpCreationCallstackAttrName());
 
     if (callstack.empty()) {
-      throw exception;
+      throw;
     }
     std::ostringstream sout;
     sout << "Invoke operator " << Type() << " error.\n";
@@ -206,7 +206,7 @@ void OperatorBase::Run(const Scope& scope, const platform::Place& place) {
     sout << "C++ Callstacks: \n";
     sout << exception.err_str_;
     exception.err_str_ = sout.str();
-    throw exception;
+    throw;
   } catch (...) {
     std::rethrow_exception(std::current_exception());
   }
@@ -589,7 +589,7 @@ class RuntimeInferShapeContext : public InferShapeContext {
  public:
   RuntimeInferShapeContext(const OperatorBase& op, const Scope& scope,
                            const RuntimeContext& ctx)
-      : op_(op), scope_(scope), ctx_(ctx) {}
+      : op_(op), ctx_(ctx) {}
 
   bool HasInput(const std::string& name) const override {
     // has only one input
@@ -881,7 +881,6 @@ class RuntimeInferShapeContext : public InferShapeContext {
   }
 
   const OperatorBase& op_;
-  const Scope& scope_;
   const RuntimeContext& ctx_;
 };
 

paddle/fluid/framework/operator.h

@@ -222,12 +222,7 @@ class ExecutionContext {
     if (it == ctx_.inputs.end()) {
       return {};
     }
-    std::vector<const Variable*> res;
-    res.reserve(it->second.size());
-    std::transform(it->second.begin(), it->second.end(),
-                   std::back_inserter(res),
-                   [this](Variable* var) { return var; });
-    return res;
+    return {it->second.begin(), it->second.end()};
   }
 
   std::vector<Variable*> MultiOutputVar(const std::string& name) const {

paddle/fluid/inference/analysis/ir_pass_manager.cc

@@ -101,7 +101,7 @@ std::unique_ptr<Graph> IRPassManager::Apply(std::unique_ptr<Graph> graph) {
     }
     graph = pass->Apply(std::move(graph));
   }
-  return std::move(graph);
+  return graph;
 }
 
 framework::proto::ProgramDesc IRPassManager::AcquireProgram(

paddle/fluid/inference/api/analysis_predictor.cc

@@ -421,7 +421,7 @@ std::unique_ptr<PaddlePredictor> CreatePaddlePredictor<
   if (!dynamic_cast<AnalysisPredictor *>(predictor.get())->Init(nullptr)) {
     return nullptr;
   }
-  return std::move(predictor);
+  return predictor;
 }
 
 void AnalysisPredictor::PrepareFeedFetch() {

paddle/fluid/memory/allocation/allocator_facade.cc

@@ -83,7 +83,7 @@ class ChunkedAllocator : public Allocator {
         VLOG(1) << "Create AutoIncrementAllocator with chunk_size "
                 << max_chunk_size_ << " and capacity " << capacity;
         default_allocator_ = std::make_shared<AutoIncrementAllocator>(
-            [this] { return std::move(CreateAllocatorWithChunk()); }, capacity);
+            [this] { return CreateAllocatorWithChunk(); }, capacity);
       }
     }
 

paddle/fluid/operators/jit/gen/act.h

@@ -63,7 +63,6 @@ class VActFunc : public JitCode {
  public:
   explicit VActFunc(size_t code_size, void* code_ptr)
       : JitCode(code_size, code_ptr) {}
-  virtual const char* name() const = 0;
   virtual void genCode() = 0;
 
  protected:

paddle/fluid/operators/jit/gen/blas.h

@@ -41,7 +41,7 @@ class VXXJitCode : public JitCode {
     this->genCode();
   }
 
-  virtual const char* name() const {
+  virtual const char* name() const override {
     std::string base = "VXXJitCode";
     if (scalar_index_ == 1) {
       base += "_Scalar";

paddle/fluid/operators/jit/gen/hopv.h

@@ -35,7 +35,7 @@ class HOPVJitCode : public JitCode {
     this->genCode();
   }
 
-  virtual const char* name() const {
+  virtual const char* name() const override {
     std::string base = "VXXJitCode";
     if (type_ == operand_type::MAX) {
       base += "_MAX";

paddle/fluid/operators/jit/gen/jitcode.h

@@ -68,7 +68,6 @@ class JitCode : public GenBase, public Xbyak::CodeGenerator {
             (code_size % 4096 != 0 ? (code_size / 4096 + 1) * 4096 : code_size),
             code_ptr) {}
 
-  virtual const char* name() const = 0;
   virtual void genCode() = 0;
 
   size_t getSize() const override { return CodeGenerator::getSize(); }

paddle/fluid/operators/jit/gen/matmul.h

@@ -36,7 +36,7 @@ class MatMulJitCode : public JitCode {
     this->genCode();
   }
 
-  virtual const char* name() const {
+  virtual const char* name() const override {
     std::string base = "MatMulJitCode";
     base = base + "_M" + std::to_string(m_) + "_N" + std::to_string(n_) + "_K" +
            std::to_string(k_);

paddle/fluid/operators/jit/gen/seqpool.h

@@ -38,7 +38,7 @@ class SeqPoolJitCode : public JitCode {
     this->genCode();
   }
 
-  virtual const char* name() const {
+  virtual const char* name() const override {
     std::string base = "SeqPoolJitCode";
     if (type_ == SeqPoolType::kSum) {
       base += "_Sum";

paddle/fluid/pybind/inference_api.cc

@@ -74,12 +74,12 @@ void BindPaddleBuf(py::module *m) {
       .def(py::init([](std::vector<float> &data) {
         auto buf = PaddleBuf(data.size() * sizeof(float));
         std::memcpy(buf.data(), static_cast<void *>(data.data()), buf.length());
-        return std::move(buf);
+        return buf;
       }))
       .def(py::init([](std::vector<int64_t> &data) {
         auto buf = PaddleBuf(data.size() * sizeof(int64_t));
         std::memcpy(buf.data(), static_cast<void *>(data.data()), buf.length());
-        return std::move(buf);
+        return buf;
       }))
       .def("resize", &PaddleBuf::Resize)
       .def("reset",