From 83641788d1ff3bc737903a81b9521cf8ba1a7454 Mon Sep 17 00:00:00 2001
From: Sungkeun Cho <scho@fb.com>
Date: Fri, 18 Sep 2020 07:20:30 -0700
Subject: [PATCH] [cost] Use prefix convention not returning autoreleased
 object

Summary: By naming convention, methods start with "alloc", "new", "copy", and "mutableCopy" return non-autoreleased object. Let's avoid raising issues in that case.

Reviewed By: ezgicicek

Differential Revision: D23565512

fbshipit-source-id: e7aa58ea9
---
 infer/src/cost/cost.ml                                 | 10 ++++++++++
 .../codetoanalyze/objc/autoreleasepool/cost-issues.exp |  8 ++++----
 .../codetoanalyze/objc/autoreleasepool/no_arc_caller.m |  8 ++++----
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/infer/src/cost/cost.ml b/infer/src/cost/cost.ml
index 7ca209885..3d35294a2 100644
--- a/infer/src/cost/cost.ml
+++ b/infer/src/cost/cost.ml
@@ -56,6 +56,15 @@ module InstrBasicCostWithReason = struct
     String.equal (Procname.get_method callee_pname) "autorelease"
 
 
+  (** The methods whose name start with one of the prefixes return an object that is owned by the
+      caller. Therefore ARC will not add any objects they return into an autorelease pool. *)
+  let return_object_owned_by_caller =
+    let prefixes = ["alloc"; "new"; "copy"; "mutableCopy"] in
+    fun callee_pname ->
+      let method_name = Procname.get_method callee_pname in
+      List.exists prefixes ~f:(fun prefix -> String.is_prefix method_name ~prefix)
+
+
   let is_objc_call_from_no_arc_to_arc {proc_resolve_attributes} caller_pdesc callee_pname =
     (not (Procdesc.is_objc_arc_on caller_pdesc))
     && Option.exists (proc_resolve_attributes callee_pname)
@@ -127,6 +136,7 @@ module InstrBasicCostWithReason = struct
         else if
           is_objc_call_from_no_arc_to_arc extras cfg callee_pname
           && Typ.is_pointer_to_objc_class ret_typ
+          && not (return_object_owned_by_caller callee_pname)
         then
           let autoreleasepool_trace =
             Bounds.BoundTrace.of_arc_from_non_arc (Procname.to_string callee_pname) location
diff --git a/infer/tests/codetoanalyze/objc/autoreleasepool/cost-issues.exp b/infer/tests/codetoanalyze/objc/autoreleasepool/cost-issues.exp
index f7620d2c8..dce262f7a 100644
--- a/infer/tests/codetoanalyze/objc/autoreleasepool/cost-issues.exp
+++ b/infer/tests/codetoanalyze/objc/autoreleasepool/cost-issues.exp
@@ -34,11 +34,11 @@ codetoanalyze/objc/autoreleasepool/no_arc_callee.m, NoArcCallee.dealloc, 0,  OnU
 codetoanalyze/objc/autoreleasepool/no_arc_callee.m, NoArcCallee.giveMeObject, 1,  OnUIThread:false, [autorelease,Modeled call to autorelease]
 codetoanalyze/objc/autoreleasepool/no_arc_callee.m, NoArcCallee.mutableCopyObject:, 0,  OnUIThread:false, []
 codetoanalyze/objc/autoreleasepool/no_arc_callee.m, NoArcCallee.newObject, 0,  OnUIThread:false, []
-codetoanalyze/objc/autoreleasepool/no_arc_caller.m, NoArcCaller.callAllocObject_zero_FP:, n,  OnUIThread:false, [{n},Loop,autorelease,ARC function call to ArcCallee.allocObject from non-ARC caller]
-codetoanalyze/objc/autoreleasepool/no_arc_caller.m, NoArcCaller.callCopyObject_zero_FP:x:, n,  OnUIThread:false, [{n},Loop,autorelease,ARC function call to ArcCallee.copyObject: from non-ARC caller]
+codetoanalyze/objc/autoreleasepool/no_arc_caller.m, NoArcCaller.callAllocObject_zero:, 0,  OnUIThread:false, []
+codetoanalyze/objc/autoreleasepool/no_arc_caller.m, NoArcCaller.callCopyObject_zero:x:, 0,  OnUIThread:false, []
 codetoanalyze/objc/autoreleasepool/no_arc_caller.m, NoArcCaller.callGiveMeInt_zero, 0,  OnUIThread:false, []
 codetoanalyze/objc/autoreleasepool/no_arc_caller.m, NoArcCaller.callGiveMeObject_autoreleasepool_zero:, 0,  OnUIThread:false, []
 codetoanalyze/objc/autoreleasepool/no_arc_caller.m, NoArcCaller.callGiveMeObject_linear:, n,  OnUIThread:false, [{n},Loop,autorelease,ARC function call to ArcCallee.giveMeObject from non-ARC caller]
-codetoanalyze/objc/autoreleasepool/no_arc_caller.m, NoArcCaller.callMutableCopyObject_zero_FP:x:, n,  OnUIThread:false, [{n},Loop,autorelease,ARC function call to ArcCallee.mutableCopyObject: from non-ARC caller]
-codetoanalyze/objc/autoreleasepool/no_arc_caller.m, NoArcCaller.callNewObject_zero_FP:, n,  OnUIThread:false, [{n},Loop,autorelease,ARC function call to ArcCallee.newObject from non-ARC caller]
+codetoanalyze/objc/autoreleasepool/no_arc_caller.m, NoArcCaller.callMutableCopyObject_zero:x:, 0,  OnUIThread:false, []
+codetoanalyze/objc/autoreleasepool/no_arc_caller.m, NoArcCaller.callNewObject_zero:, 0,  OnUIThread:false, []
 codetoanalyze/objc/autoreleasepool/no_arc_caller.m, NoArcCaller.dealloc, 0,  OnUIThread:false, []
diff --git a/infer/tests/codetoanalyze/objc/autoreleasepool/no_arc_caller.m b/infer/tests/codetoanalyze/objc/autoreleasepool/no_arc_caller.m
index 5a04669cd..dbf2fabb1 100644
--- a/infer/tests/codetoanalyze/objc/autoreleasepool/no_arc_caller.m
+++ b/infer/tests/codetoanalyze/objc/autoreleasepool/no_arc_caller.m
@@ -12,25 +12,25 @@
 
 @implementation NoArcCaller
 
-- (void)callAllocObject_zero_FP:(int)n {
+- (void)callAllocObject_zero:(int)n {
   for (int i = 0; i < n; i++) {
     ArcCallee* obj = [ArcCallee allocObject];
   }
 }
 
-- (void)callNewObject_zero_FP:(int)n {
+- (void)callNewObject_zero:(int)n {
   for (int i = 0; i < n; i++) {
     ArcCallee* obj = [ArcCallee newObject];
   }
 }
 
-- (void)callCopyObject_zero_FP:(int)n x:(ArcCallee*)x {
+- (void)callCopyObject_zero:(int)n x:(ArcCallee*)x {
   for (int i = 0; i < n; i++) {
     ArcCallee* obj = [ArcCallee copyObject:x];
   }
 }
 
-- (void)callMutableCopyObject_zero_FP:(int)n x:(ArcCallee*)x {
+- (void)callMutableCopyObject_zero:(int)n x:(ArcCallee*)x {
   for (int i = 0; i < n; i++) {
     ArcCallee* obj = [ArcCallee mutableCopyObject:x];
   }