From 97cb854e5ce80a297c215f0ed74987fba1bdf711 Mon Sep 17 00:00:00 2001
From: Josh Berdine <jjb@fb.com>
Date: Thu, 17 Mar 2016 07:16:13 -0700
Subject: [PATCH] Model NSArray::arrayWithObject

Summary:public
This models [NSArray arrayWithObject:o] to require [o] to be non-nil,
reporting NULL_DEREFERENCE otherwise.

Reviewed By: jvillard

Differential Revision: D2968563

fb-gh-sync-id: 04ae123
shipit-source-id: 04ae123
---
 infer/models/objc/src/NSArray.m                    |  5 +++++
 .../objc/errors/npe/nil_in_array_literal.m         | 14 ++++++++++++++
 infer/tests/endtoend/objc/NPEArrayLiteralTest.java |  3 ++-
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/infer/models/objc/src/NSArray.m b/infer/models/objc/src/NSArray.m
index c73bdb125..b36f3a03a 100644
--- a/infer/models/objc/src/NSArray.m
+++ b/infer/models/objc/src/NSArray.m
@@ -15,4 +15,9 @@
   return [NSArray alloc];
 }
 
++ (instancetype)arrayWithObject:(char*)anObject {
+  char _ = *anObject;
+  return [NSArray alloc];
+}
+
 @end
diff --git a/infer/tests/codetoanalyze/objc/errors/npe/nil_in_array_literal.m b/infer/tests/codetoanalyze/objc/errors/npe/nil_in_array_literal.m
index 934af3287..d8422fcea 100644
--- a/infer/tests/codetoanalyze/objc/errors/npe/nil_in_array_literal.m
+++ b/infer/tests/codetoanalyze/objc/errors/npe/nil_in_array_literal.m
@@ -19,6 +19,10 @@
   NSArray* foo = @[ @"aaa", @"bbb" ];
   // check that array literals create valid objects
   NSArray* foofoo = @[ foo ];
+  NSArray* bar = [NSArray arrayWithObject:@"ccc"];
+  // test return value of arrayWithObject to avoid RETURN_VALUE_IGNORED report
+  if (bar)
+    return;
 }
 
 - (void)nilInArrayLiteral0 {
@@ -49,11 +53,21 @@
   NSArray* foo = @[ @"aaa", @"bbb", str ];
 }
 
+- (NSArray*)nilInArrayWithObject {
+  NSString* str = nil;
+
+  // nil argument in arrayWithObject crashes
+  NSArray* foo = [NSArray arrayWithObject:str];
+
+  return foo;
+}
+
 @end
 
 int main() {
   A* a = [A alloc];
   [a noProblem];
   [a nilInArrayLiteral0];
+  [a nilInArrayWithObject];
   return 0;
 }
diff --git a/infer/tests/endtoend/objc/NPEArrayLiteralTest.java b/infer/tests/endtoend/objc/NPEArrayLiteralTest.java
index 356f6007c..b5d30d413 100644
--- a/infer/tests/endtoend/objc/NPEArrayLiteralTest.java
+++ b/infer/tests/endtoend/objc/NPEArrayLiteralTest.java
@@ -63,7 +63,8 @@ public class NPEArrayLiteralTest {
         "nilInArrayLiteral0",
         "nilInArrayLiteral1",
         "nilInArrayLiteral2",
-        "nilInArrayLiteral3"
+        "nilInArrayLiteral3",
+        "nilInArrayWithObject"
     };
     assertThat(
         "Only NPE should be found", inferResults,