Fix unsqueeze with empty axis bug (#51828)

paddle/phi/infermeta/unary.cc

@@ -4791,15 +4791,10 @@ void UnsqueezeInferMeta(const MetaTensor& x,
     std::vector<int64_t> vec_out_dims(output_size, -1);
     out->set_dtype(x.dtype());
     out->set_dims(phi::make_ddim(vec_out_dims));
-  } else if (!axes.GetData().empty()) {
-    std::vector<int32_t> tmp;
-    tmp.reserve(axes.GetData().size());
-    std::for_each(axes.GetData().begin(),
-                  axes.GetData().end(),
-                  [&tmp](const int64_t& t) { tmp.push_back(t); });
-    auto out_dims = funcs::GetUnsqueezeShape(tmp, x_dims);
+  } else {
+    auto out_dims = funcs::GetUnsqueezeShape(axes.GetData(), x_dims);
     out->set_dims(out_dims);
-    if (x_dims[0] == out_dims[0]) {
+    if (x_dims.size() > 0 && x_dims[0] == out_dims[0]) {
       out->share_lod(x);
     }
     out->set_dtype(x.dtype());

paddle/phi/kernels/funcs/unsqueeze.h

@@ -103,7 +103,7 @@ inline DDim GetOutputSqueezeShape(const std::vector<int> squeeze_dims,
   return phi::make_ddim(output_shape);
 }
 
-inline DDim GetUnsqueezeShape(const std::vector<int> unsqz_dims,
+inline DDim GetUnsqueezeShape(const std::vector<int64_t> unsqz_dims,
                               const DDim& in_dims) {
   int output_size = in_dims.size() + static_cast<int>(unsqz_dims.size());
   int cur_output_size = in_dims.size();

paddle/phi/kernels/unsqueeze_kernel.cc

@@ -28,12 +28,7 @@ void UnsqueezeInferKernel(const Context& dev_ctx,
   auto x_dims = x.dims();
   auto out_dims = out->dims();
   if (axes.FromTensor()) {
-    std::vector<int32_t> tmp;
-    tmp.reserve(axes.GetData().size());
-    std::for_each(axes.GetData().begin(),
-                  axes.GetData().end(),
-                  [&tmp](const int64_t& t) { tmp.push_back(t); });
-    out_dims = funcs::GetUnsqueezeShape(tmp, x_dims);
+    out_dims = funcs::GetUnsqueezeShape(axes.GetData(), x_dims);
   }
   out->Resize(out_dims);
   dev_ctx.template Alloc<T>(out);

python/paddle/fluid/tests/unittests/test_unsqueeze_op.py

@@ -108,6 +108,22 @@ class TestUnsqueezeOp4(TestUnsqueezeOp):
         self.new_shape = (10, 1, 1, 2, 5, 1)
 
 
+# axis is empty, x is ND
+class TestUnsqueezeOp5(TestUnsqueezeOp):
+    def init_test_case(self):
+        self.ori_shape = ()
+        self.axes = ()
+        self.new_shape = ()
+
+
+# axis is empty, x is 0D
+class TestUnsqueezeOp6(TestUnsqueezeOp):
+    def init_test_case(self):
+        self.ori_shape = (10, 2, 5)
+        self.axes = ()
+        self.new_shape = (10, 2, 5)
+
+
 class TestUnsqueezeOp_ZeroDim1(TestUnsqueezeOp):
     def init_test_case(self):
         self.ori_shape = ()