[Frontend][C++] Add support for default params

Summary:
@public
Add support for default function arguments.
As a side change - always create cmethod_signature for a function

Test Plan:
1. Call function with default parameter and confirm that it gets parsed and reports null dereference (B5 but still). It didn't before.
2. Created a test case

infer/src/clang/cMethod_decl.ml

@@ -50,7 +50,7 @@ struct
       | ParmVarDecl(decl_info, name, qtype, var_decl_info) ->
           Printing.log_out "Adding  param '%s' " name;
           Printing.log_out "with pointer %s@." decl_info.Clang_ast_t.di_pointer;
-          (name, CTypes.get_type qtype)
+          (name, CTypes.get_type qtype, var_decl_info.vdi_init_expr)
       | _ -> assert false in
     match function_method_decl_info with
     | Func_decl_info (function_decl_info, _) ->
@@ -58,7 +58,7 @@ struct
     | Meth_decl_info (method_decl_info, class_name) ->
         let pars = list_map par_to_ms_par method_decl_info.Clang_ast_t.omdi_parameters in
         if (is_instance_method function_method_decl_info false false) then
-          ("self", class_name):: pars
+          ("self", class_name, None):: pars
         else pars
 
   let get_return_type function_method_decl_info =
@@ -154,6 +154,7 @@ struct
         let is_objc_method = is_anonym_block in
         let curr_class = if is_anonym_block then curr_class else CContext.ContextNoCls in
         let attributes = CMethod_signature.ms_get_attributes ms in
+        CMethod_signature.add ms;
         add_method tenv cg cfg curr_class procname namespace [body] is_objc_method is_instance
           captured_vars is_anonym_block fdecl_info.Clang_ast_t.fdi_parameters attributes
     | None, ms ->
@@ -166,6 +167,7 @@ struct
     let method_decl = Meth_decl_info (method_decl_info, class_name) in
     let ms = build_method_signature decl_info procname method_decl false false in
     Printing.log_out " ....Processing implementation for method '%s'\n" (Procname.to_string procname);
+    CMethod_signature.add ms;
     (match method_body_to_translate decl_info ms method_decl_info.Clang_ast_t.omdi_body with
       | Some body ->
           let is_instance = CMethod_signature.ms_is_instance ms in
@@ -173,8 +175,7 @@ struct
           CMethod_trans.create_local_procdesc cfg tenv ms [body] [] is_instance;
           add_method tenv cg cfg curr_class procname namespace [body] true is_instance [] false
             method_decl_info.Clang_ast_t.omdi_parameters attributes
-      | None ->
+      | None -> ())
-          CMethod_signature.add ms)
 
   let rec process_one_method_decl tenv cg cfg curr_class namespace dec =
     match dec with

infer/src/clang/cMethod_signature.ml

@@ -8,7 +8,7 @@
 
 type method_signature = {
   _name : Procname.t;
-  _args : (string * string) list; (* (name, type) *)
+  _args : (string * string * Clang_ast_t.stmt option) list; (* (name, type, default value) *)
   _ret_type : string;
   _attributes : Clang_ast_t.attribute list;
   _loc : Clang_ast_t.source_range;
@@ -52,7 +52,7 @@ let replace_name_ms ms name =
 
 let ms_to_string ms =
   "Method "^(Procname.to_string ms._name)^" "^
-  (Utils.list_to_string (fun (s1, s2) -> s1^", "^s2) ms._args)^"->"^ms._ret_type^" "^
+  (Utils.list_to_string (fun (s1, s2, _) -> s1^", "^s2) ms._args)^"->"^ms._ret_type^" "^
   Clang_ast_j.string_of_source_range ms._loc
 
 let find ms =

infer/src/clang/cMethod_signature.mli

@@ -16,7 +16,7 @@ val reset_map : unit -> unit
 
 val ms_get_name : method_signature -> Procname.t
 
-val ms_get_args : method_signature -> (string * string) list
+val ms_get_args : method_signature -> (string * string * Clang_ast_t.stmt option) list
 
 val ms_get_ret_type : method_signature -> string
 
@@ -26,7 +26,7 @@ val ms_get_loc : method_signature -> Clang_ast_t.source_range
 
 val ms_is_instance : method_signature -> bool
 
-val make_ms : Procname.t -> (string * string) list -> string -> Clang_ast_t.attribute list ->
+val make_ms : Procname.t -> (string * string * Clang_ast_t.stmt option) list -> string -> Clang_ast_t.attribute list ->
 Clang_ast_t.source_range -> bool -> method_signature
 
 val replace_name_ms : method_signature -> Procname.t -> method_signature

infer/src/clang/cMethod_trans.ml

@@ -87,7 +87,7 @@ let get_formal_parameters tenv ms =
   let rec defined_parameters pl =
     match pl with
     | [] -> []
-    | (name, raw_type):: pl' ->
+    | (name, raw_type, _):: pl' ->
         let qt =
           if (name = CFrontend_config.self && CMethod_signature.ms_is_instance ms) then
             (Ast_expressions.create_pointer_type raw_type)

infer/src/clang/cTrans.ml

@@ -539,7 +539,28 @@ struct
         (* verbatim from a call to a different function, and they might be side-effecting *)
         (Procname.to_string pn) <> CFrontend_config.builtin_object_size
       | _ -> true in
-    let params_stmt = if should_translate_args then params_stmt else [] in
+
+    let assign_default_params params_stmt =
+      match callee_pname_opt with
+      | None -> params_stmt
+      | Some callee_pname ->
+        try
+          let callee_ms = CMethod_signature.find callee_pname in
+          let args = CMethod_signature.ms_get_args callee_ms in
+          let params_args = list_combine params_stmt args in
+          let replace_default_arg param =
+            match param with
+            | CXXDefaultArgExpr(_, _, _), (_, _, Some default_instr) -> default_instr
+            | instr, _ -> instr in
+          list_map replace_default_arg params_args
+        with
+        | Invalid_argument _ ->
+          (* list_combine failed because of different list lengths *)
+          Printing.log_err "Param count doesn't match %s\n" (Procname.to_string callee_pname);
+          params_stmt
+        | Not_found -> params_stmt in
+
+    let params_stmt = if should_translate_args then assign_default_params params_stmt else [] in
     let res_trans_par =
       let l = list_map (fun i -> exec_with_self_exception instruction trans_state_param i) params_stmt in
       let rt = collect_res_trans (res_trans_callee :: l) in

infer/src/clang/cTrans_models.ml

@@ -130,7 +130,7 @@ let get_predefined_ms_method condition class_name method_name mk_procname
 
 let get_predefined_ms_stringWithUTF8String class_name method_name mk_procname =
   let condition = class_name = nsstring_cl && method_name = string_with_utf8_m in
-  get_predefined_ms_method condition class_name method_name mk_procname [("x", "char *")]
+  get_predefined_ms_method condition class_name method_name mk_procname [("x", "char *", None)]
     id_cl [] None
 
 let get_predefined_ms_retain_release class_name method_name mk_procname =
@@ -139,17 +139,17 @@ let get_predefined_ms_retain_release class_name method_name mk_procname =
     if is_retain_method method_name || is_autorelease_method method_name
     then id_cl else void in
   get_predefined_ms_method condition nsobject_cl method_name mk_procname
-    [(self, class_name)] return_type [] (get_builtinname method_name)
+    [(self, class_name, None)] return_type [] (get_builtinname method_name)
 
 let get_predefined_ms_autoreleasepool_init class_name method_name mk_procname =
   let condition = (method_name = init) && (class_name = nsautorelease_pool_cl) in
   get_predefined_ms_method condition class_name method_name mk_procname
-    [(self, class_name)] void [] None
+    [(self, class_name, None)] void [] None
 
 let get_predefined_ms_nsautoreleasepool_release class_name method_name mk_procname =
   let condition = (method_name = release || method_name = drain) &&
     (class_name = nsautorelease_pool_cl) in
-  get_predefined_ms_method condition class_name method_name mk_procname [(self, class_name)]
+  get_predefined_ms_method condition class_name method_name mk_procname [(self, class_name, None)]
     void [] (Some SymExec.ModelBuiltins.__objc_release_autorelease_pool)
 
 let get_predefined_model_method_signature class_name method_name mk_procname =

infer/tests/codetoanalyze/cpp/frontend/types/functions.cpp

@@ -0,0 +1,18 @@
+int fun_default(int a = 3, int b = 5) {
+  return a + b;
+}
+
+int fun_default_decl(int a, int b = 5);
+// note that b is default param, but function was declared earlier
+int fun_default_decl(int a, int b) {
+  return a + b;
+}
+
+void test() {
+  fun_default(1, 2);
+  fun_default(1);
+  fun_default();
+
+  fun_default_decl(6);
+  fun_default_decl(6,6);
+}

infer/tests/codetoanalyze/cpp/frontend/types/functions.dot

@@ -0,0 +1,51 @@
+digraph iCFG {
+13 [label="13:  Call _fun_fun_default \n   n$8=_fun_fun_default(1:int ,2:int ) [line 12]\n  REMOVE_TEMPS(n$8); [line 12]\n " shape="box"]
+	
+
+	 13 -> 12 ;
+12 [label="12:  Call _fun_fun_default \n   n$7=_fun_fun_default(1:int ,5:int ) [line 13]\n  REMOVE_TEMPS(n$7); [line 13]\n " shape="box"]
+	
+
+	 12 -> 11 ;
+11 [label="11:  Call _fun_fun_default \n   n$6=_fun_fun_default(3:int ,5:int ) [line 14]\n  REMOVE_TEMPS(n$6); [line 14]\n " shape="box"]
+	
+
+	 11 -> 10 ;
+10 [label="10:  Call _fun_fun_default_decl \n   n$5=_fun_fun_default_decl(6:int ,5:int ) [line 16]\n  REMOVE_TEMPS(n$5); [line 16]\n " shape="box"]
+	
+
+	 10 -> 9 ;
+9 [label="9:  Call _fun_fun_default_decl \n   n$4=_fun_fun_default_decl(6:int ,6:int ) [line 17]\n  REMOVE_TEMPS(n$4); [line 17]\n  APPLY_ABSTRACTION; [line 17]\n " shape="box"]
+	
+
+	 9 -> 8 ;
+8 [label="8: Exit test \n  " color=yellow style=filled]
+	
+
+7 [label="7: Start test\nFormals: \nLocals:  \n   DECLARE_LOCALS(&return); [line 11]\n " color=yellow style=filled]
+	
+
+	 7 -> 13 ;
+6 [label="6:  Return Stmt \n   n$2=*&a:int  [line 8]\n  n$3=*&b:int  [line 8]\n  *&return:int =(n$2 + n$3) [line 8]\n  REMOVE_TEMPS(n$2,n$3); [line 8]\n  NULLIFY(&a,false); [line 8]\n  NULLIFY(&b,false); [line 8]\n  APPLY_ABSTRACTION; [line 8]\n " shape="box"]
+	
+
+	 6 -> 5 ;
+5 [label="5: Exit fun_default_decl \n  " color=yellow style=filled]
+	
+
+4 [label="4: Start fun_default_decl\nFormals:  a:int  b:int \nLocals:  \n   DECLARE_LOCALS(&return); [line 7]\n " color=yellow style=filled]
+	
+
+	 4 -> 6 ;
+3 [label="3:  Return Stmt \n   n$0=*&a:int  [line 2]\n  n$1=*&b:int  [line 2]\n  *&return:int =(n$0 + n$1) [line 2]\n  REMOVE_TEMPS(n$0,n$1); [line 2]\n  NULLIFY(&a,false); [line 2]\n  NULLIFY(&b,false); [line 2]\n  APPLY_ABSTRACTION; [line 2]\n " shape="box"]
+	
+
+	 3 -> 2 ;
+2 [label="2: Exit fun_default \n  " color=yellow style=filled]
+	
+
+1 [label="1: Start fun_default\nFormals:  a:int  b:int \nLocals:  \n   DECLARE_LOCALS(&return); [line 1]\n " color=yellow style=filled]
+	
+
+	 1 -> 3 ;
+}

infer/tests/frontend/cpp/FunctionsTest.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2013- Facebook.
+ * All rights reserved.
+ */
+
+package frontend.cpp;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static utils.matchers.DotFilesEqual.dotFileEqualTo;
+
+import com.google.common.collect.ImmutableList;
+
+import org.junit.Rule;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.IOException;
+
+import utils.DebuggableTemporaryFolder;
+import utils.InferException;
+import utils.InferRunner;
+
+public class FunctionsTest {
+
+  @Rule
+  public DebuggableTemporaryFolder folder = new DebuggableTemporaryFolder();
+
+  @Test
+  public void whenCaptureRunCommaThenDotFilesAreTheSame()
+      throws InterruptedException, IOException, InferException {
+    String literal_src =
+        "infer/tests/codetoanalyze/cpp/frontend/types/functions.cpp";
+
+    String literal_dotty =
+        "infer/tests/codetoanalyze/cpp/frontend/types/functions.dot";
+
+    ImmutableList<String> inferCmd =
+        InferRunner.createCPPInferCommandFrontend(
+            folder,
+            literal_src);
+    File newDotFile = InferRunner.runInferFrontend(inferCmd);
+    assertThat(
+        "In the capture of " + literal_src +
+            " the dotty files should be the same.",
+        newDotFile, dotFileEqualTo(literal_dotty));
+  }
+}