Instrument: fix the handling of declarations in while loop conditions

This fixes the handling of "while (T var = expr)" C++ constructs.

TN: V816-018
Change-Id: Icd1a0a47f9608ed1472aaa7f255c96973540da20

Author: pmderodat

tools/gnatcov/clang-extensions.ads

@@ -39,6 +39,12 @@ package Clang.Extensions is
    function Get_For_Inc (C : Cursor_T) return Cursor_T
      with Import, Convention => C, External_Name => "clang_getForInc";
 
+   function Get_Cond_Var (C : Cursor_T) return Cursor_T
+     with Import, Convention => C, External_Name => "clang_getCondVar";
+
+   function Get_Var_Init_Expr (C : Cursor_T) return Cursor_T
+     with Import, Convention => C, External_Name => "clang_getVarInitExpr";
+
    function Get_Then (C : Cursor_T) return Cursor_T
      with Import, Convention => C, External_Name => "clang_getThen";
 

tools/gnatcov/clang-wrapper.cc

@@ -59,6 +59,15 @@ MakeCXCursorWithNull (const Stmt *S, CXCursor C)
     return clang_getNullCursor ();
 }
 
+CXCursor
+MakeCXCursorWithNull (const Decl *decl, CXCursor C)
+{
+  if (decl)
+    return MakeCXCursor (decl, getCursorTU (C));
+  else
+    return clang_getNullCursor ();
+}
+
 /* Most of the functions are getters around existing clang functions of a
    similar name, for the accepted type(s).  For instance, clang_getCond will
    simply call getCond on the given node, if this is a statement or an
@@ -181,6 +190,40 @@ clang_getForInc (CXCursor C)
   return clang_getNullCursor ();
 }
 
+extern "C" CXCursor
+clang_getCondVar (CXCursor C)
+{
+  const Stmt *stmt;
+  const WhileStmt *while_stmt;
+  const VarDecl *decl;
+
+  if (clang_isStatement (C.kind)
+      && (stmt = cxcursor::getCursorStmt (C))
+      && stmt->getStmtClass () == Stmt::WhileStmtClass)
+    {
+      while_stmt = cast<WhileStmt> (stmt);
+      if (decl = while_stmt->getConditionVariable ())
+        return MakeCXCursorWithNull (decl, C);
+    }
+  return clang_getNullCursor ();
+}
+
+extern "C" CXCursor
+clang_getVarInitExpr (CXCursor C)
+{
+  const Decl *decl;
+  const VarDecl *var_decl;
+
+  if (clang_isDeclaration (C.kind)
+      && (decl = cxcursor::getCursorDecl (C))
+      && decl->getKind () == Decl::Kind::Var)
+    {
+      var_decl = cast<VarDecl> (decl);
+      return MakeCXCursorWithNull (var_decl->getInit (), C);
+    }
+  return clang_getNullCursor ();
+}
+
 extern "C" CXCursor
 clang_getThen (CXCursor C)
 {

tools/gnatcov/instrument-c.adb

@@ -1898,16 +1898,24 @@ package body Instrument.C is
             when Cursor_While_Stmt =>
                declare
                   While_Body     : constant Cursor_T := Get_Body (N);
+                  Cond_Var       : constant Cursor_T := Get_Cond_Var (N);
                   Cond           : constant Cursor_T := Get_Cond (N);
                   Inner_Dominant : constant Dominant_Info := ('S', N);
 
                begin
                   UIC.Pass.Curlify (N   => While_Body,
                                     Rew => UIC.Rewriter);
+
+                  --  If the loop condition is a declaration, instrument its
+                  --  initialization expression.
+
                   Extend_Statement_Sequence
                     (N, 'W',
-                     Insertion_N  => Cond,
+                     Insertion_N  => (if Is_Null (Cond_Var)
+                                      then Cond
+                                      else Get_Var_Init_Expr (Cond_Var)),
                      Instr_Scheme => Instr_Expr);
+
                   Process_Decisions_Defer (Cond, 'W');
                   Set_Statement_Entry;
                   Traverse_Statements

tools/gnatcov/instrument-c.ads

@@ -119,11 +119,6 @@ package Instrument.C is
    --  very well be a goto pointing inside the loop, making it skip the
    --  execution of the witness statement, but we would still be executing the
    --  condition of the loop on the second iteration.
-   --
-   --  TODO??? we still have to figure out what should be done with such valid
-   --  C++ constructs:
-   --
-   --    while (int i = calc()){}
 
    type C_Source_Statement is record
       LL_SCO : Nat;