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

@@ -15,4 +15,9 @@
   return [NSArray alloc];
 }
 
++ (instancetype)arrayWithObject:(char*)anObject {
+  char _ = *anObject;
+  return [NSArray alloc];
+}
+
 @end

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;
 }

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,