[componentkit] Skip implicit variables during MLV check

Reviewed By: dulmarod

Differential Revision: D4084601

fbshipit-source-id: 1c919cd

infer/src/clang/ComponentKit.ml

@@ -86,7 +86,7 @@ let mutable_local_vars_advice context decl =
     | _ -> false in
 
   match decl with
-  | Clang_ast_t.VarDecl(decl_info, _, qual_type, _) ->
+  | Clang_ast_t.VarDecl(decl_info, named_decl_info, qual_type, _) ->
       let is_const_ref = match Ast_utils.get_type qual_type.qt_type_ptr with
         | Some LValueReferenceType (_, {Clang_ast_t.qt_is_const}) ->
             qt_is_const
@@ -95,11 +95,13 @@ let mutable_local_vars_advice context decl =
       let condition = is_ck_context context decl
                       && (not (Ast_utils.is_syntactically_global_var decl))
                       && (not is_const)
-                      && not (is_of_whitelisted_type qual_type) in
+                      && not (is_of_whitelisted_type qual_type)
+                      && not decl_info.di_is_implicit in
       if condition then
         Some {
           CIssue.issue = CIssue.Mutable_local_variable_in_component_file;
-          CIssue.description = "Local variables should be const to avoid reassignment";
+          CIssue.description = "Local variable '" ^ named_decl_info.ni_name
+                               ^ "' should be const to avoid reassignment";
           CIssue.suggestion = Some "Add a const (after the asterisk for pointer types).";
           CIssue.loc = CFrontend_checkers.location_from_dinfo context decl_info
         }

infer/tests/codetoanalyze/objcpp/linters/componentkit/MutableLocalVariablesTest.mm

@@ -9,6 +9,9 @@
 
 #import <Foundation/Foundation.h>
 
+#include <vector>
+#include <stdio.h>
+
 #import "FakeComponentKitHeader.h"
 
 @interface CKLabelComponent : CKCompositeComponent
@@ -37,6 +40,7 @@
     NSString* foo = @"HI"; // error
     _foo = foo;
   }
+  return nil;
 }
 @end
 
@@ -100,5 +104,25 @@ class BarClass {
   NSError const* __autoreleasing* e2; // no error
   NSError* const* e3 = &e; // no error
   NSError* const* const e4 = &e; // no error
+
+  // implicit vars (e.g. ones generated in a for loop statement)
+  const std::vector<const int> const_vector_of_const_int = {1, 2, 3};
+  for (int i : const_vector_of_const_int) { // error
+    printf("%d", i);
+  }
+  for (const int i : const_vector_of_const_int) {
+    printf("%d", i);
+  }
+  for (auto i : const_vector_of_const_int) { // auto != const int; error
+    printf("%d", i);
+  }
+  for (const auto i : const_vector_of_const_int) {
+    printf("%d", i);
+  }
+  for (auto& i : const_vector_of_const_int) { // auto == const int; no error
+    printf("%d", i);
+  }
+
+  return nil;
 }
 @end

infer/tests/codetoanalyze/objcpp/linters/issues.exp

@@ -8,14 +8,16 @@ componentkit/InitializerWithSideEffectTest.mm, __objc_anonymous_block_______1, 3
 componentkit/InitializerWithSideEffectTest.mm, __objc_anonymous_block_______2, 41, COMPONENT_INITIALIZER_WITH_SIDE_EFFECTS
 componentkit/MultipleFactoryMethodsTest.h, Linters_dummy_method, 18, COMPONENT_WITH_MULTIPLE_FACTORY_METHODS
 componentkit/MultipleFactoryMethodsTest.h, Linters_dummy_method, 27, COMPONENT_WITH_MULTIPLE_FACTORY_METHODS
-componentkit/MutableLocalVariablesTest.mm, BarComponent_new, 85, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
-componentkit/MutableLocalVariablesTest.mm, BarComponent_new, 87, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
-componentkit/MutableLocalVariablesTest.mm, FooComponent_newWithString:, 48, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
-componentkit/MutableLocalVariablesTest.mm, FooComponent_newWithString:, 53, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
-componentkit/MutableLocalVariablesTest.mm, FooComponent_newWithString:, 55, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
+componentkit/MutableLocalVariablesTest.mm, BarComponent_new, 89, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
+componentkit/MutableLocalVariablesTest.mm, BarComponent_new, 91, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
+componentkit/MutableLocalVariablesTest.mm, BarComponent_new, 110, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
+componentkit/MutableLocalVariablesTest.mm, BarComponent_new, 116, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
+componentkit/MutableLocalVariablesTest.mm, FooComponent_newWithString:, 52, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
+componentkit/MutableLocalVariablesTest.mm, FooComponent_newWithString:, 57, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
 componentkit/MutableLocalVariablesTest.mm, FooComponent_newWithString:, 59, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
-componentkit/MutableLocalVariablesTest.mm, FooComponent_newWithString:, 64, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
-componentkit/MutableLocalVariablesTest.mm, SomeClass_init, 37, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
+componentkit/MutableLocalVariablesTest.mm, FooComponent_newWithString:, 63, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
+componentkit/MutableLocalVariablesTest.mm, FooComponent_newWithString:, 68, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
+componentkit/MutableLocalVariablesTest.mm, SomeClass_init, 40, MUTABLE_LOCAL_VARIABLE_IN_COMPONENT_FILE
 componentkit/UnconventionalSuperclassTest.h, Linters_dummy_method, 17, COMPONENT_WITH_UNCONVENTIONAL_SUPERCLASS
 cxx_reference_in_block/block.mm, A_foo3:param2:, 37, CXX_REFERENCE_CAPTURED_IN_OBJC_BLOCK
 cxx_reference_in_block/block.mm, A_foo:, 20, CXX_REFERENCE_CAPTURED_IN_OBJC_BLOCK