Fix LayerNorm tester for gcc4.8 (#30962)

paddle/fluid/framework/ir/layer_norm_fuse_pass_tester.cc

@@ -43,21 +43,21 @@ class LayerNormFuseTest {
              "division_out", "scale_out", "shift_out"},
             {"sqr_pow", "eps", "gamma", "beta"})},
         m_place{},
-        m_exe{m_place},
-        m_block_desc{m_prog.Block(0)} {
-    auto* x_var_desc = m_block_desc.FindVar("x");
+        m_exe{m_place} {
+    const BlockDesc& block_desc = m_prog.Block(0);
+    auto* x_var_desc = block_desc.FindVar("x");
     x_var_desc->SetDataType(proto::VarType::FP32);
     x_var_desc->SetShape({3, 32, 48});
 
-    auto* eps_var_desc = m_block_desc.FindVar("eps");
+    auto* eps_var_desc = block_desc.FindVar("eps");
     eps_var_desc->SetDataType(proto::VarType::FP32);
     eps_var_desc->SetShape({1});
 
-    auto* gamma_var_desc = m_block_desc.FindVar("gamma");
+    auto* gamma_var_desc = block_desc.FindVar("gamma");
     gamma_var_desc->SetDataType(proto::VarType::FP32);
     gamma_var_desc->SetShape({48});
 
-    auto* beta_var_desc = m_block_desc.FindVar("beta");
+    auto* beta_var_desc = block_desc.FindVar("beta");
     beta_var_desc->SetDataType(proto::VarType::FP32);
     beta_var_desc->SetShape({48});
 
@@ -102,7 +102,7 @@ class LayerNormFuseTest {
       : LayerNormFuseTest() {
     m_removed_nodes = removed_nodes;
     m_added_nodes = added_nodes;
-    func(m_block_desc);
+    func(m_prog.Block(0));
   }
 
   void setupGraph() {
@@ -165,7 +165,6 @@ class LayerNormFuseTest {
   ProgramDesc m_prog;
   paddle::platform::CPUPlace m_place;
   NaiveExecutor m_exe;
-  const BlockDesc& m_block_desc;
   Scope m_scope;
   std::unique_ptr<Graph> m_graph{nullptr};
 };