[clang][dead stores] translate init-capture expressions

Summary:
Not translating these properly was causing false positives for the dead store analysis in cases like

```
int i = 0;
return [j = i]() { return j; }();
```

Reviewed By: da319

Differential Revision: D5731562

fbshipit-source-id: ae79ac8

infer/src/clang/cTrans.ml

@@ -2587,7 +2587,7 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
     | _
      -> assert false
 
-  and lambdaExpr_trans trans_state expr_info {Clang_ast_t.lei_lambda_decl; lei_captures} =
+  and lambdaExpr_trans trans_state stmt_info expr_info {Clang_ast_t.lei_lambda_decl; lei_captures} =
     let open CContext in
     let qual_type = expr_info.Clang_ast_t.ei_qual_type in
     let context = trans_state.context in
@@ -2598,19 +2598,40 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
     (* We need to set the explicit dependency between the newly created lambda and the *)
     (* defining procedure. We add an edge in the call graph.*)
     Cg.add_edge context.cg procname lambda_pname ;
-    let captured_vars =
-      List.fold_right
-        ~f:(fun {Clang_ast_t.lci_captured_var} acc ->
-          match lci_captured_var with
-          | Some decl_ref
-           -> CVar_decl.sil_var_of_captured_var decl_ref context procname :: acc
-          | None
-           -> acc)
-        ~init:[] lei_captures
-      |> List.map ~f:(fun (pvar, typ) -> (Exp.Lvar pvar, pvar, typ))
-    in
+    let make_captured_tuple (pvar, typ) = (Exp.Lvar pvar, pvar, typ) in
+    let get_captured_pvar_typ decl_ref =
+      CVar_decl.sil_var_of_captured_var decl_ref context procname
+    in
+    let translate_capture_init (pvar, typ) init_decl =
+      match init_decl with
+      | Clang_ast_t.VarDecl (_, _, _, {vdi_init_expr})
+       -> init_expr_trans trans_state (Exp.Lvar pvar, typ) stmt_info vdi_init_expr
+      | _
+       -> L.die ExternalError "Unexpected: capture-init statement without var decl"
+    in
+    let translate_captured {Clang_ast_t.lci_captured_var; lci_init_captured_vardecl}
+        (trans_results_acc, captured_vars_acc as acc) =
+      match (lci_captured_var, lci_init_captured_vardecl) with
+      | Some captured_var_decl_ref, Some init_decl
+       -> (* capture and init *)
+          let pvar_typ = get_captured_pvar_typ captured_var_decl_ref in
+          ( translate_capture_init pvar_typ init_decl :: trans_results_acc
+          , make_captured_tuple pvar_typ :: captured_vars_acc )
+      | Some captured_var_decl_ref, None
+       -> (* just capture *)
+          let pvar_typ = get_captured_pvar_typ captured_var_decl_ref in
+          (trans_results_acc, make_captured_tuple pvar_typ :: captured_vars_acc)
+      | None, None
+       -> acc
+      | None, Some _
+       -> L.die InternalError "Capture-init with init, but no capture"
+    in
+    let trans_results, captured_vars =
+      List.fold_right ~f:translate_captured ~init:([], []) lei_captures
+    in
+    let final_trans_result = collect_res_trans context.procdesc trans_results in
     let closure = Exp.Closure {name= lambda_pname; captured_vars} in
-    {empty_res_trans with exps= [(closure, typ)]}
+    {final_trans_result with exps= [(closure, typ)]}
 
   and cxxNewExpr_trans trans_state stmt_info expr_info cxx_new_expr_info =
     let context = trans_state.context in
@@ -3116,9 +3137,9 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
      -> cxxTypeidExpr_trans trans_state stmt_info stmts expr_info
     | CXXStdInitializerListExpr (stmt_info, stmts, expr_info)
      -> cxxStdInitializerListExpr_trans trans_state stmt_info stmts expr_info
-    | LambdaExpr (_, _, expr_info, lambda_expr_info)
+    | LambdaExpr (stmt_info, _, expr_info, lambda_expr_info)
      -> let trans_state' = {trans_state with priority= Free} in
-        lambdaExpr_trans trans_state' expr_info lambda_expr_info
+        lambdaExpr_trans trans_state' stmt_info expr_info lambda_expr_info
     | AttributedStmt (_, stmts, attrs)
      -> attributedStmt_trans trans_state stmts attrs
     | TypeTraitExpr (_, _, expr_info, type_trait_info)

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

@@ -171,7 +171,7 @@ codetoanalyze/cpp/errors/smart_ptr/weak_ptr.cpp, weak_ptr_observers::lock_can_be
 codetoanalyze/cpp/errors/smart_ptr/weak_ptr.cpp, weak_ptr_observers::shared_still_in_scope_good_FP, 6, NULL_DEREFERENCE, [start of procedure weak_ptr_observers::shared_still_in_scope_good_FP()]
 codetoanalyze/cpp/errors/smart_ptr/weak_ptr.cpp, weak_ptr_observers::use_count_after_reset_bad, 5, use_count after weak_ptr reset is 0, [start of procedure weak_ptr_observers::use_count_after_reset_bad(),Condition is true,return from a call to weak_ptr_observers::use_count_after_reset_bad]
 codetoanalyze/cpp/errors/smart_ptr/weak_ptr.cpp, weak_ptr_observers::use_count_empty_bad, 5, use_count on empty weak_ptr is 0, [start of procedure weak_ptr_observers::use_count_empty_bad(),Condition is true,return from a call to weak_ptr_observers::use_count_empty_bad]
-codetoanalyze/cpp/errors/smart_ptr/weak_ptr_compil.cpp, weak_ptr_lock_repro_large::RDC::create::lambda_smart_ptr_weak_ptr_compil.cpp:62:7_operator(), 2, Cannot_star, [start of procedure operator(),Condition is true]
+codetoanalyze/cpp/errors/smart_ptr/weak_ptr_compil.cpp, weak_ptr_lock_repro_large::RDC::create::lambda_smart_ptr_weak_ptr_compil.cpp:62:7_operator(), 2, Cannot_star, [start of procedure operator(),Condition is true,Skipping function: function or method not found]
 codetoanalyze/cpp/errors/stack_escape/basic.cpp, B_return_ref, 0, STACK_VARIABLE_ADDRESS_ESCAPE, [start of procedure return_ref,start of procedure A,return from a call to A_A,return from a call to B_return_ref]
 codetoanalyze/cpp/errors/stack_escape/basic.cpp, basic_escape_local_bad, 3, STACK_VARIABLE_ADDRESS_ESCAPE, [start of procedure basic_escape_local_bad(),return from a call to basic_escape_local_bad]
 codetoanalyze/cpp/errors/stack_escape/basic.cpp, basic_escape_param_bad, 0, STACK_VARIABLE_ADDRESS_ESCAPE, [start of procedure basic_escape_param_bad(),return from a call to basic_escape_param_bad]

infer/tests/codetoanalyze/cpp/liveness/Makefile

@@ -9,7 +9,7 @@ TESTS_DIR = ../../..
 
 ANALYZER = checkers
 # see explanations in cpp/errors/Makefile for the custom isystem
-CLANG_OPTIONS = -x c++ -std=c++11 -nostdinc++ -isystem$(MODELS_DIR)/cpp/include -isystem$(CLANG_INCLUDES)/c++/v1/ -c
+CLANG_OPTIONS = -x c++ -std=c++14 -nostdinc++ -isystem$(MODELS_DIR)/cpp/include -isystem$(CLANG_INCLUDES)/c++/v1/ -c
 INFER_OPTIONS = --liveness --ml-buckets cpp --debug-exceptions --project-root $(TESTS_DIR) --no-keep-going
 INFERPRINT_OPTIONS = --issues-tests
 

infer/tests/codetoanalyze/cpp/liveness/dead_stores.cpp

@@ -51,8 +51,19 @@ void FN_capture_no_read_bad() {
   [x]() { return; }();
 }
 
-void FN_init_capture_no_read_bad() {
-  [i = 0]() { return; };
+void init_capture_reassign_bad() {
+  int i = 0; // this is a dead store
+  return [i = 0]() { return i; }
+  ();
+}
+
+void init_capture_no_call_bad() {
+  [i = 0]() { return i; };
+}
+
+int FN_init_capture_no_read_bad() {
+  return [i = 0]() { return 0; }
+  ();
 }
 
 int return_ok() {
@@ -167,8 +178,44 @@ int FN_capture_by_ref_reuseBad() {
   return x;
 }
 
-void init_capture_ok() {
-  [i = 0]() { return i; };
+int init_capture1_ok() {
+  return [i = 0]() { return i; }
+  ();
+}
+
+int init_capture2_ok() {
+  int i = 0;
+  return [j = i]() { return j; }
+  ();
+}
+
+int init_capture3_ok() {
+  int i = 0;
+  return [i = i]() { return i; }
+  ();
+}
+
+int init_capture4_ok() {
+  int i = 0;
+  int j = 0;
+  return [ a = 0, b = i, c = j ]() { return a + b + c; }
+  ();
+}
+
+int init_capture5_ok() {
+  int i = 0;
+  int k = [j = i]() { return j; }
+  ();
+  i = 5; // should not be flagged
+  return i + k;
+}
+
+int init_capture6_ok() {
+  int i = 0;
+  int k = [i = i + 1]() { return i; }
+  ();
+  i = 5; // should not be flagged;
+  return i + k;
 }
 
 char* global;
@@ -179,4 +226,5 @@ void FP_assign_array_tricky_ok() {
   *(int*)arr = 123; // think this is a bug in the frontend... this instruction
   // looks like &arr:int = 123
 }
+
 }

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

@@ -2,7 +2,9 @@ codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::FP_assign_array_tricky_
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::dead_pointer_bad, 2, DEAD_STORE, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::dead_then_live_bad, 1, DEAD_STORE, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::easy_bad, 0, DEAD_STORE, [Write of unused value]
-codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::lambda_bad::lambda_dead_stores.cpp:128:11_operator(), 1, DEAD_STORE, [Write of unused value]
+codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::init_capture_no_call_bad, 1, DEAD_STORE, [Write of unused value]
+codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::init_capture_reassign_bad, 1, DEAD_STORE, [Write of unused value]
+codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::lambda_bad::lambda_dead_stores.cpp:139:11_operator(), 1, DEAD_STORE, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::plus_plus1_bad, 2, DEAD_STORE, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::plus_plus2_bad, 2, DEAD_STORE, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::plus_plus3_bad, 2, DEAD_STORE, [Write of unused value]

infer/tests/codetoanalyze/cpp/shared/lambda/lambda1.cpp

@@ -39,6 +39,13 @@ int capture_by_ref() {
   return x;
 }
 
-void init_capture() {
-  [i = 0]() { i; };
+int init_capture1() {
+  return [i = 0]() { return i; }
+  ();
+}
+
+int init_capture2() {
+  int i = 0;
+  return [ a = i, b = 0, c = 3 ]() { return a + b + c; }
+  ();
 }

infer/tests/codetoanalyze/cpp/shared/lambda/lambda1.cpp.dot

@@ -87,13 +87,48 @@ digraph iCFG {
 	
 
 	 "capture_by_ref#_Z14capture_by_refv.c683a8db53a834aa19283088dfffe460_5" -> "capture_by_ref#_Z14capture_by_refv.c683a8db53a834aa19283088dfffe460_4" ;
-"init_capture#_Z12init_capturev.b56a308a8fe2b749cb39e3b566237ec2_1" [label="1: Start init_capture\nFormals: \nLocals:  \n   DECLARE_LOCALS(&return); [line 42]\n " color=yellow style=filled]
+"init_capture1#_Z13init_capture1v.7519553572919eb8fa8af50760159e66_1" [label="1: Start init_capture1\nFormals: \nLocals:  \n   DECLARE_LOCALS(&return); [line 42]\n " color=yellow style=filled]
 	
 
-	 "init_capture#_Z12init_capturev.b56a308a8fe2b749cb39e3b566237ec2_1" -> "init_capture#_Z12init_capturev.b56a308a8fe2b749cb39e3b566237ec2_2" ;
-"init_capture#_Z12init_capturev.b56a308a8fe2b749cb39e3b566237ec2_2" [label="2: Exit init_capture \n  " color=yellow style=filled]
+	 "init_capture1#_Z13init_capture1v.7519553572919eb8fa8af50760159e66_1" -> "init_capture1#_Z13init_capture1v.7519553572919eb8fa8af50760159e66_3" ;
+"init_capture1#_Z13init_capture1v.7519553572919eb8fa8af50760159e66_2" [label="2: Exit init_capture1 \n  " color=yellow style=filled]
 	
 
+"init_capture1#_Z13init_capture1v.7519553572919eb8fa8af50760159e66_3" [label="3:  DeclStmt \n   *&i:int=0 [line 43]\n " shape="box"]
+	
+
+	 "init_capture1#_Z13init_capture1v.7519553572919eb8fa8af50760159e66_3" -> "init_capture1#_Z13init_capture1v.7519553572919eb8fa8af50760159e66_4" ;
+"init_capture1#_Z13init_capture1v.7519553572919eb8fa8af50760159e66_4" [label="4:  Return Stmt \n   n$0=_fun_init_capture1::lambda_shared_lambda_lambda1.cpp:43:10_operator()((_fun_init_capture1::lambda_shared_lambda_lambda1.cpp:43:10_operator(),&i):init_capture1::lambda_shared_lambda_lambda1.cpp:43:10) [line 43]\n  *&return:int=n$0 [line 43]\n " shape="box"]
+	
+
+	 "init_capture1#_Z13init_capture1v.7519553572919eb8fa8af50760159e66_4" -> "init_capture1#_Z13init_capture1v.7519553572919eb8fa8af50760159e66_2" ;
+"init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_1" [label="1: Start init_capture2\nFormals: \nLocals:  i:int \n   DECLARE_LOCALS(&return,&i); [line 47]\n " color=yellow style=filled]
+	
+
+	 "init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_1" -> "init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_7" ;
+"init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_2" [label="2: Exit init_capture2 \n  " color=yellow style=filled]
+	
+
+"init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_3" [label="3:  DeclStmt \n   *&c:int=3 [line 49]\n " shape="box"]
+	
+
+	 "init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_3" -> "init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_6" ;
+"init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_4" [label="4:  DeclStmt \n   *&b:int=0 [line 49]\n " shape="box"]
+	
+
+	 "init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_4" -> "init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_3" ;
+"init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_5" [label="5:  DeclStmt \n   n$0=*&i:int [line 49]\n  *&a:int=n$0 [line 49]\n " shape="box"]
+	
+
+	 "init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_5" -> "init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_4" ;
+"init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_6" [label="6:  Return Stmt \n   n$1=_fun_init_capture2::lambda_shared_lambda_lambda1.cpp:49:10_operator()((_fun_init_capture2::lambda_shared_lambda_lambda1.cpp:49:10_operator(),&a,&b,&c):init_capture2::lambda_shared_lambda_lambda1.cpp:49:10) [line 49]\n  *&return:int=n$1 [line 49]\n " shape="box"]
+	
+
+	 "init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_6" -> "init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_2" ;
+"init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_7" [label="7:  DeclStmt \n   *&i:int=0 [line 48]\n " shape="box"]
+	
+
+	 "init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_7" -> "init_capture2#_Z13init_capture2v.ea2bbe7e5f5b3cec548b40ebd7beb345_5" ;
 "operator()#lambda_shared_lambda_lambda1.cpp:11:15#bar#(_ZZ3barvENK3$_0clEv).6e24f7d75fa4d9b98ee11419b33635ae_1" [label="1: Start bar::lambda_shared_lambda_lambda1.cpp:11:15_operator()\nFormals:  this:bar::lambda_shared_lambda_lambda1.cpp:11:15*\nLocals:  i:int \n   DECLARE_LOCALS(&return,&i); [line 11]\n " color=yellow style=filled]
 	
 
@@ -192,11 +227,26 @@ digraph iCFG {
 	
 
 	 "operator()#lambda_shared_lambda_lambda1.cpp:38:3#capture_by_ref#(_ZZ14capture_by_refvENK3$_5clEv).801ff4a46ab35f8d28f7ad0e26ae456e_3" -> "operator()#lambda_shared_lambda_lambda1.cpp:38:3#capture_by_ref#(_ZZ14capture_by_refvENK3$_5clEv).801ff4a46ab35f8d28f7ad0e26ae456e_2" ;
-"operator()#lambda_shared_lambda_lambda1.cpp:43:3#init_capture#(_ZZ12init_capturevENK3$_6clEv).43d5b008ae982e3438cddd48c4a55f04_1" [label="1: Start init_capture::lambda_shared_lambda_lambda1.cpp:43:3_operator()\nFormals:  this:init_capture::lambda_shared_lambda_lambda1.cpp:43:3*\nLocals:  \n   DECLARE_LOCALS(&return); [line 43]\n " color=yellow style=filled]
+"operator()#lambda_shared_lambda_lambda1.cpp:43:10#init_capture1#(_ZZ13init_capture1vENK3$_6clEv).184e351188c1ce3cde6eb3d7757baeac_1" [label="1: Start init_capture1::lambda_shared_lambda_lambda1.cpp:43:10_operator()\nFormals:  this:init_capture1::lambda_shared_lambda_lambda1.cpp:43:10*\nLocals:  \n   DECLARE_LOCALS(&return); [line 43]\n " color=yellow style=filled]
+	
+
+	 "operator()#lambda_shared_lambda_lambda1.cpp:43:10#init_capture1#(_ZZ13init_capture1vENK3$_6clEv).184e351188c1ce3cde6eb3d7757baeac_1" -> "operator()#lambda_shared_lambda_lambda1.cpp:43:10#init_capture1#(_ZZ13init_capture1vENK3$_6clEv).184e351188c1ce3cde6eb3d7757baeac_3" ;
+"operator()#lambda_shared_lambda_lambda1.cpp:43:10#init_capture1#(_ZZ13init_capture1vENK3$_6clEv).184e351188c1ce3cde6eb3d7757baeac_2" [label="2: Exit init_capture1::lambda_shared_lambda_lambda1.cpp:43:10_operator() \n  " color=yellow style=filled]
+	
+
+"operator()#lambda_shared_lambda_lambda1.cpp:43:10#init_capture1#(_ZZ13init_capture1vENK3$_6clEv).184e351188c1ce3cde6eb3d7757baeac_3" [label="3:  Return Stmt \n   n$0=*&i:int [line 43]\n  *&return:int=n$0 [line 43]\n " shape="box"]
+	
+
+	 "operator()#lambda_shared_lambda_lambda1.cpp:43:10#init_capture1#(_ZZ13init_capture1vENK3$_6clEv).184e351188c1ce3cde6eb3d7757baeac_3" -> "operator()#lambda_shared_lambda_lambda1.cpp:43:10#init_capture1#(_ZZ13init_capture1vENK3$_6clEv).184e351188c1ce3cde6eb3d7757baeac_2" ;
+"operator()#lambda_shared_lambda_lambda1.cpp:49:10#init_capture2#(_ZZ13init_capture2vENK3$_7clEv).1c25acd20a722db722068b75ba66296b_1" [label="1: Start init_capture2::lambda_shared_lambda_lambda1.cpp:49:10_operator()\nFormals:  this:init_capture2::lambda_shared_lambda_lambda1.cpp:49:10*\nLocals:  \n   DECLARE_LOCALS(&return); [line 49]\n " color=yellow style=filled]
+	
+
+	 "operator()#lambda_shared_lambda_lambda1.cpp:49:10#init_capture2#(_ZZ13init_capture2vENK3$_7clEv).1c25acd20a722db722068b75ba66296b_1" -> "operator()#lambda_shared_lambda_lambda1.cpp:49:10#init_capture2#(_ZZ13init_capture2vENK3$_7clEv).1c25acd20a722db722068b75ba66296b_3" ;
+"operator()#lambda_shared_lambda_lambda1.cpp:49:10#init_capture2#(_ZZ13init_capture2vENK3$_7clEv).1c25acd20a722db722068b75ba66296b_2" [label="2: Exit init_capture2::lambda_shared_lambda_lambda1.cpp:49:10_operator() \n  " color=yellow style=filled]
 	
 
-	 "operator()#lambda_shared_lambda_lambda1.cpp:43:3#init_capture#(_ZZ12init_capturevENK3$_6clEv).43d5b008ae982e3438cddd48c4a55f04_1" -> "operator()#lambda_shared_lambda_lambda1.cpp:43:3#init_capture#(_ZZ12init_capturevENK3$_6clEv).43d5b008ae982e3438cddd48c4a55f04_2" ;
-"operator()#lambda_shared_lambda_lambda1.cpp:43:3#init_capture#(_ZZ12init_capturevENK3$_6clEv).43d5b008ae982e3438cddd48c4a55f04_2" [label="2: Exit init_capture::lambda_shared_lambda_lambda1.cpp:43:3_operator() \n  " color=yellow style=filled]
+"operator()#lambda_shared_lambda_lambda1.cpp:49:10#init_capture2#(_ZZ13init_capture2vENK3$_7clEv).1c25acd20a722db722068b75ba66296b_3" [label="3:  Return Stmt \n   n$0=*&a:int [line 49]\n  n$1=*&b:int [line 49]\n  n$2=*&c:int [line 49]\n  *&return:int=((n$0 + n$1) + n$2) [line 49]\n " shape="box"]
 	
 
+	 "operator()#lambda_shared_lambda_lambda1.cpp:49:10#init_capture2#(_ZZ13init_capture2vENK3$_7clEv).1c25acd20a722db722068b75ba66296b_3" -> "operator()#lambda_shared_lambda_lambda1.cpp:49:10#init_capture2#(_ZZ13init_capture2vENK3$_7clEv).1c25acd20a722db722068b75ba66296b_2" ;
 }