codegen: Ensure API structs don't collide with API client type name (#…

…3651)

Updates the SDK's code generation to renames structures that collide
with the service's API client struct name.

For example, service Foo, has struct shape named Foo. The API client
type would be generated as Foo, and the colliding struct shape would be
renamed to Foo_, with a trailing underscore(_).

private/model/api/passes.go

@@ -334,6 +334,12 @@ func (a *API) renameExportable() {
 		}
 
 		newName := a.ExportableName(k)
+		if s.Type == "structure" && newName == a.StructName() {
+			// If struct collides client's struct type name the shape needs to
+			// be renamed with a trailing `_` to prevent collision.
+			newName += "_"
+		}
+
 		if newName != s.ShapeName {
 			s.Rename(newName)
 		}

private/model/api/passes_test.go

@@ -576,6 +576,42 @@ func TestCreateInputOutputShapes(t *testing.T) {
 				"FirstOpInput", "FirstOpOutput",
 			},
 		},
+		"collidingShape": {
+			API: &API{
+				name:     "APIClientName",
+				Metadata: meta,
+				Operations: map[string]*Operation{
+					"FirstOp": {Name: "FirstOp",
+						InputRef: ShapeRef{ShapeName: "FirstOpRequest"},
+					},
+				},
+				Shapes: map[string]*Shape{
+					"FirstOpRequest": {ShapeName: "FirstOpRequest", Type: "structure",
+						MemberRefs: map[string]*ShapeRef{
+							"Foo": {ShapeName: "APIClientName"},
+							"ooF": {ShapeName: "APIClientNameList"},
+						},
+					},
+					"APIClientName": {
+						ShapeName: "APIClientName", Type: "structure",
+					},
+					"APIClientNameList": {
+						ShapeName: "APIClientNameList", Type: "list",
+						MemberRef: ShapeRef{ShapeName: "APIClientName"},
+					},
+				},
+			},
+			ExpectOps: map[string]OpExpect{
+				"FirstOp": {
+					Input:  "FirstOpInput",
+					Output: "FirstOpOutput",
+				},
+			},
+			ExpectShapes: []string{
+				"APIClientNameList", "APIClientName_",
+				"FirstOpInput", "FirstOpOutput",
+			},
+		},
 	}
 
 	for name, c := range cases {