[infer][nullable checker] only report once when the return of a nullable method is derferenced several times

Summary: This is to avoid reporting several times the issue.

Reviewed By: mbouaziz

Differential Revision: D6230418

fbshipit-source-id: e51506c

infer/src/checkers/NullabilityCheck.ml

@@ -122,7 +122,7 @@ module TransferFunctions (CFG : ProcCfg.S) = struct
           astate
       | Some (nullable_ap, call_sites) ->
           report_nullable_dereference nullable_ap call_sites proc_data loc ;
-          remove_nullable_ap receiver astate )
+          assume_pnames_notnull receiver astate )
     | Call (Some ret_var, _, _, _, _) ->
         remove_nullable_ap (ret_var, []) astate
     | Assign (lhs, rhs, loc)

infer/tests/codetoanalyze/cpp/nullable/issues.exp

@@ -29,6 +29,9 @@ codetoanalyze/cpp/nullable/method.cpp, methodNotAlwaysCheckedForNullBad, 2, NULL
 codetoanalyze/cpp/nullable/method.cpp, methodNotAlwaysCheckedForNullBad, 2, NULL_DEREFERENCE, [start of procedure methodNotAlwaysCheckedForNullBad(),Condition is false,start of procedure mayReturnNullObject,Condition is false,return from a call to T_mayReturnNullObject,Condition is true,start of procedure mayReturnNullObject,Condition is false,return from a call to T_mayReturnNullObject]
 codetoanalyze/cpp/nullable/method.cpp, nullableAssignmentInOneBranchBad, 7, NULLABLE_DEREFERENCE, [deference of &p,assignment of the nullable value,definition of mayReturnNullObject]
 codetoanalyze/cpp/nullable/method.cpp, nullableAssignmentInOneBranchBad, 7, NULL_DEREFERENCE, [start of procedure nullableAssignmentInOneBranchBad(),Condition is true,start of procedure mayReturnNullObject,Condition is true,return from a call to T_mayReturnNullObject]
+codetoanalyze/cpp/nullable/method.cpp, onlyReportOnceBad, 1, NULLABLE_DEREFERENCE, [deference of n$6,definition of mayReturnNullObject]
+codetoanalyze/cpp/nullable/method.cpp, onlyReportOnceBad, 1, NULL_DEREFERENCE, [start of procedure onlyReportOnceBad(),start of procedure mayReturnNullObject,Condition is false,return from a call to T_mayReturnNullObject]
+codetoanalyze/cpp/nullable/method.cpp, onlyReportOnceBad, 3, NULL_DEREFERENCE, [start of procedure onlyReportOnceBad(),start of procedure mayReturnNullObject,Condition is false,return from a call to T_mayReturnNullObject,start of procedure doSomething,return from a call to T_doSomething,start of procedure mayReturnNullObject,Condition is false,return from a call to T_mayReturnNullObject]
 codetoanalyze/cpp/nullable/method.cpp, reportsViolationInNotNullElseBranchBad, 1, NULL_TEST_AFTER_DEREFERENCE, [start of procedure reportsViolationInNotNullElseBranchBad(),start of procedure mayReturnNullObject,Condition is false,return from a call to T_mayReturnNullObject,Condition is false]
 codetoanalyze/cpp/nullable/method.cpp, reportsViolationInNotNullElseBranchBad, 3, NULLABLE_DEREFERENCE, [deference of n$5,definition of mayReturnNullObject]
 codetoanalyze/cpp/nullable/method.cpp, reportsViolationInNotNullElseBranchBad, 3, NULL_DEREFERENCE, [start of procedure reportsViolationInNotNullElseBranchBad(),start of procedure mayReturnNullObject,Condition is true,return from a call to T_mayReturnNullObject,Condition is false,start of procedure mayReturnNullObject,Condition is false,return from a call to T_mayReturnNullObject]

infer/tests/codetoanalyze/cpp/nullable/method.cpp

@@ -123,3 +123,9 @@ void methodNotAlwaysCheckedForNullBad(T* t) {
     t->mayReturnNullObject()->doSomething(); // reports here
   }
 }
+
+void onlyReportOnceBad(T* t) {
+  t->mayReturnNullObject()->doSomething(); // reports here
+  // ...
+  t->mayReturnNullObject()->doSomething(); // does not report here
+}