From 2efa22073cbc1d335676f0d426414531224878dd Mon Sep 17 00:00:00 2001
From: Jules Villard <jul@fb.com>
Date: Tue, 17 Nov 2020 11:58:15 -0800
Subject: [PATCH] [clang] force node creation in switch statements

Summary:
The translation of `switch` cases needs to insert nodes around the
translation of each `case` sub-statement, so we need to force node
creation in these sub-statements so the nodes around it can be connected
to the translation of the sub-statements.

Also added more logging I found useful when debugging that.

Reviewed By: da319

Differential Revision: D24991455

fbshipit-source-id: d3a622142
---
 infer/src/clang/SwitchCase.ml                 |  4 ++--
 infer/src/clang/cTrans.ml                     | 20 ++++++++++++++-----
 .../cpp/liveness/dead_stores.cpp              | 10 ++++++++++
 3 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/infer/src/clang/SwitchCase.ml b/infer/src/clang/SwitchCase.ml
index cc6b41b85..b6b9d5583 100644
--- a/infer/src/clang/SwitchCase.ml
+++ b/infer/src/clang/SwitchCase.ml
@@ -26,12 +26,12 @@ let add switch_case = current_cases := switch_case :: !current_cases
 
 let pp_condition fmt = function
   | Case stmt ->
-      F.fprintf fmt "case %a:" (Pp.of_string ~f:Clang_ast_j.string_of_stmt) stmt
+      F.fprintf fmt "case %a:" (Pp.of_string ~f:Clang_ast_proj.get_stmt_kind_string) stmt
   | Default ->
       F.pp_print_string fmt "default:"
 
 
 let pp fmt {condition; root_nodes} =
-  F.fprintf fmt "%a -> @[<h>[%a]@]" pp_condition condition
+  F.fprintf fmt "%a->@[<h>[%a]@]" pp_condition condition
     (Pp.semicolon_seq Procdesc.Node.pp)
     root_nodes
diff --git a/infer/src/clang/cTrans.ml b/infer/src/clang/cTrans.ml
index c03ea2f42..e6ddbeb00 100644
--- a/infer/src/clang/cTrans.ml
+++ b/infer/src/clang/cTrans.ml
@@ -1938,9 +1938,12 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
       | _ ->
           assert false
     in
-    let body_trans_result = instruction trans_state body in
-    (let open SwitchCase in
-    add {condition= Case condition; stmt_info; root_nodes= body_trans_result.control.root_nodes}) ;
+    L.debug Capture Verbose "translating a caseStmt@\n" ;
+    let body_trans_result = exec_with_node_creation ~f:instruction trans_state body in
+    L.debug Capture Verbose "result of translating a caseStmt: %a@\n" pp_control
+      body_trans_result.control ;
+    SwitchCase.add
+      {condition= Case condition; stmt_info; root_nodes= body_trans_result.control.root_nodes} ;
     body_trans_result
 
 
@@ -2013,7 +2016,11 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
     let switch_cases, (_ : trans_result) =
       SwitchCase.in_switch_body ~f:(instruction inner_trans_state) body
     in
-    let link_up_switch_cases curr_succ_nodes = function
+    let link_up_switch_cases curr_succ_nodes case =
+      L.debug Capture Verbose "switch: curr_succ_nodes=[%a], linking case %a@\n"
+        (Pp.semicolon_seq Procdesc.Node.pp)
+        curr_succ_nodes SwitchCase.pp case ;
+      match (case : SwitchCase.t) with
       | {SwitchCase.condition= Case case_condition; stmt_info; root_nodes} ->
           (* create case prune nodes, link the then branch to [root_nodes], the else branch to
              [curr_succ_nodes] *)
@@ -3894,7 +3901,10 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
                   (Pp.of_string ~f:Clang_ast_proj.get_stmt_kind_string)
                   instr ) )
       in
-      L.(debug Capture Verbose) "@]" ;
+      L.debug Capture Verbose
+        "@]@\nResult of translating statement '%a' (pointer= '%a')@\ncontrol=%a@\n"
+        (Pp.of_string ~f:Clang_ast_proj.get_stmt_kind_string)
+        instr pp_pointer instr pp_control trans_result.control ;
       (* don't forget to reset this so we output messages for future errors too *)
       logged_error := false ;
       trans_result
diff --git a/infer/tests/codetoanalyze/cpp/liveness/dead_stores.cpp b/infer/tests/codetoanalyze/cpp/liveness/dead_stores.cpp
index 90d6aa46a..3cd12f752 100644
--- a/infer/tests/codetoanalyze/cpp/liveness/dead_stores.cpp
+++ b/infer/tests/codetoanalyze/cpp/liveness/dead_stores.cpp
@@ -599,4 +599,14 @@ void binaryConditional_bad() {
   int j = 42;
 }
 
+X getXFromInt(int x);
+
+void switch_with_temporary_ok() {
+  int x = 44;
+  switch (42) {
+    case 0:
+      getXFromInt(x);
+  };
+}
+
 } // namespace dead_stores