[pulse] Loosen fieldname comparison in state

Summary:
When C and C++ code handle a common struct typed value, the struct
type is handled as a `CStruct` in the C code, but as a `CppClass` in
the C++ code.  On the other hand, `Fieldname.t` contains a string of
field and **the struct type**.  As a result, even if a same field is
accessed in C and C++ code, the accessed fieldnames are different.

```
void callee_in_c(struct s* x) {
  x->a = 3;
}

void caller_in_cpp() {
  struct s x;
  x.a = 5;
  callee_in_c(&x);
  // HERE
}
```

For example, in the above code, `caller_in_cpp` sets the field `a` as
5, then calls `callee_in_c`, which sets the field `a` as 3.  However,
at `HERE`, the value of `x` in Pulse is `{a -> 5, a -> 3}`, because the two
fieldnames are addressed as different ones.

To avoid the issue, this diff loosens the fieldname comparison in
Pulse.

Reviewed By: jvillard

Differential Revision: D26000812

fbshipit-source-id: 77142ebda

infer/src/IR/Fieldname.ml

@@ -8,7 +8,12 @@
 open! IStd
 module F = Format
 
-type t = {class_name: Typ.Name.t; field_name: string} [@@deriving compare, equal, yojson_of]
+type 'typ_name t_ = {class_name: 'typ_name; field_name: string}
+[@@deriving compare, equal, yojson_of]
+
+type t = Typ.Name.t t_ [@@deriving compare, equal, yojson_of]
+
+let loose_compare = compare_t_ Typ.Name.loose_compare
 
 let make class_name field_name = {class_name; field_name}
 

infer/src/IR/Fieldname.mli

@@ -11,6 +11,9 @@ module F = Format
 (** Names for fields of class/struct/union *)
 type t [@@deriving compare, equal, yojson_of]
 
+val loose_compare : t -> t -> int
+(** Similar to compare, but addresses [CStruct x] and [CppClass x] as equal. *)
+
 val make : Typ.Name.t -> string -> t
 (** create a field of the given class and fieldname *)
 

infer/src/IR/Typ.ml

@@ -355,6 +355,20 @@ let desc_to_string desc =
 module Name = struct
   type t = name [@@deriving compare, equal, yojson_of]
 
+  (* NOTE: When a same struct type is used in C/C++/ObjC/ObjC++, their struct types may different,
+     eg [CStruct] in, C but [CppClass] in C++.  On the other hand, since [Fieldname.t] includes the
+     class names, even for the same field, its field name used in C and C++ can be different.
+     However, in analyses, we may want to *not* distinguish fieldnames of the same struct type.  For
+     that, we can use these loosened compare functions instead. *)
+  let loose_compare x y =
+    match (x, y) with
+    | (CStruct name1 | CppClass (name1, NoTemplate)), (CStruct name2 | CppClass (name2, NoTemplate))
+      ->
+        QualifiedCppName.compare name1 name2
+    | _ ->
+        compare x y
+
+
   let hash = Hashtbl.hash
 
   let qual_name = function

infer/src/IR/Typ.mli

@@ -152,6 +152,9 @@ module Name : sig
   (** Named types. *)
   type t = name [@@deriving compare, yojson_of]
 
+  val loose_compare : t -> t -> int
+  (** Similar to compare, but addresses [CStruct x] and [CppClass x] as equal. *)
+
   val equal : t -> t -> bool
   (** Equality for typenames *)
 

infer/src/absint/HilExp.ml

@@ -16,13 +16,17 @@ let yojson_of_typ_ = [%yojson_of: _]
 let compare_typ_ _ _ = 0
 
 module Access = struct
-  type 'array_index t =
-    | FieldAccess of Fieldname.t
+  type ('fieldname, 'array_index) t_ =
+    | FieldAccess of 'fieldname
     | ArrayAccess of typ_ * 'array_index
     | TakeAddress
     | Dereference
   [@@deriving compare, yojson_of]
 
+  type 'array_index t = (Fieldname.t, 'array_index) t_ [@@deriving compare, yojson_of]
+
+  let loose_compare compare_array_index = compare_t_ Fieldname.loose_compare compare_array_index
+
   let pp pp_array_index fmt = function
     | FieldAccess field_name ->
         Fieldname.pp fmt field_name

infer/src/absint/HilExp.mli

@@ -9,13 +9,18 @@ open! IStd
 module F = Format
 
 module Access : sig
-  type 'array_index t =
-    | FieldAccess of Fieldname.t
+  type ('fieldname, 'array_index) t_ =
+    | FieldAccess of 'fieldname
     | ArrayAccess of Typ.t * 'array_index
     | TakeAddress
     | Dereference
   [@@deriving compare, yojson_of]
 
+  type 'array_index t = (Fieldname.t, 'array_index) t_ [@@deriving compare, yojson_of]
+
+  val loose_compare :
+    ('array_index -> 'array_index -> int) -> 'array_index t -> 'array_index t -> int
+
   val pp : (Format.formatter -> 'array_index -> unit) -> Format.formatter -> 'array_index t -> unit
 
   val is_field_or_array_access : 'a t -> bool

infer/src/pulse/PulseBaseMemory.ml

@@ -12,7 +12,9 @@ open PulseBasicInterface
 (* {3 Heap domain } *)
 
 module Access = struct
-  type t = AbstractValue.t HilExp.Access.t [@@deriving compare, yojson_of]
+  type t = AbstractValue.t HilExp.Access.t [@@deriving yojson_of]
+
+  let compare = HilExp.Access.loose_compare AbstractValue.compare
 
   let equal = [%compare.equal: t]
 

infer/tests/clang-c-cpp.make

@@ -0,0 +1,24 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+SOURCES = $(SOURCES_C) $(SOURCES_CPP)
+
+ROOT_DIR = $(TESTS_DIR)/../..
+
+CLEAN_EXTRA += duplicates.txt
+
+OBJECTS = $(foreach source,$(filter %.c %.cpp %.m %.mm,$(SOURCES)),$(basename $(source)).o)
+
+include $(TESTS_DIR)/infer.make
+include $(TESTS_DIR)/clang-base.make
+
+infer-out$(TEST_SUFFIX)/report.json: $(CLANG_DEPS) $(SOURCES) $(HEADERS) $(TESTS_DIR)/.inferconfig $(MAKEFILE_LIST)
+	$(QUIET)$(call silent_on_success,Testing infer/clang in $(TEST_REL_DIR),\
+	  echo $(SOURCES) && \
+	  $(INFER_BIN) capture --results-dir $(@D) --dump-duplicate-symbols \
+	    $(INFER_OPTIONS) -- clang $(CLANG_OPTIONS_C) $(SOURCES_C) && \
+	  $(INFER_BIN) capture --continue --results-dir $(@D) --dump-duplicate-symbols \
+	    $(INFER_OPTIONS) -- clang $(CLANG_OPTIONS_CPP) $(SOURCES_CPP) && \
+	  $(INFER_BIN) analyze --results-dir $(@D) --dump-duplicate-symbols $(INFER_OPTIONS))

infer/tests/codetoanalyze/c_cpp/pulse/Makefile

@@ -0,0 +1,19 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+TESTS_DIR = ../../..
+
+CLANG_OPTIONS_C = -c
+CLANG_OPTIONS_CPP = -x c++ -std=c++17 -nostdinc++ -isystem$(CLANG_INCLUDES)/c++/v1/ -c
+
+INFER_OPTIONS = --pulse-only --debug-exceptions --project-root $(TESTS_DIR) \
+  --pulse-report-latent-issues
+
+INFERPRINT_OPTIONS = --issues-tests
+
+SOURCES_C = $(wildcard *.c)
+SOURCES_CPP = $(wildcard *.cpp)
+
+include $(TESTS_DIR)/clang-c-cpp.make

infer/tests/codetoanalyze/c_cpp/pulse/callee_in_c.c

@@ -0,0 +1,10 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include "callee_in_c.h"
+
+void set_field_three(struct s* x) { x->a = 3; }

infer/tests/codetoanalyze/c_cpp/pulse/callee_in_c.h

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+struct s {
+  int a;
+};
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void set_field_three(struct s* x);
+
+#ifdef __cplusplus
+}
+#endif

infer/tests/codetoanalyze/c_cpp/pulse/caller_in_cpp.cpp

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <stdlib.h>
+#include "callee_in_c.h"
+
+void call_set_field_three_Ok(int* p) {
+  struct s x;
+  x.a = 5;
+  set_field_three(&x);
+  if (x.a == 5) {
+    free(p);
+    *p = 3;
+  }
+}