Explicitly track the condition variable within an "if" statement,

rather than burying it in a CXXConditionDeclExpr (that occassionally
hides behind implicit conversions). Similar changes for
switch, while, and do-while will follow, then the removal of
CXXConditionDeclExpr. This commit is the canary.

llvm-svn: 89717

4 files changed, 48 insertions, 5 deletions

diff --git a/clang/lib/Sema/Sema.h b/clang/lib/Sema/Sema.h
index 9e20771b826..1df1ec681e0 100644
--- a/clang/lib/Sema/Sema.h
+++ b/clang/lib/Sema/Sema.h
@@ -1879,7 +1879,8 @@ public:
                                                       Declarator &D,
                                                       SourceLocation EqualLoc,
                                                       ExprArg AssignExprVal);
-
+  OwningExprResult CheckConditionVariable(VarDecl *ConditionVar);
+                                          
   /// ActOnUnaryTypeTrait - Parsed one of the unary type trait support
   /// pseudo-functions.
   virtual OwningExprResult ActOnUnaryTypeTrait(UnaryTypeTrait OTT,
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 21ab093a1a5..f2b82aa98ba 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -1002,6 +1002,27 @@ Sema::ActOnCXXConditionDeclarationExpr(Scope *S, SourceLocation StartLoc,
   return Owned(new (Context) CXXConditionDeclExpr(StartLoc, EqualLoc, VD));
 }
 
+/// \brief Check the use of the given variable as a C++ condition in an if,
+/// while, do-while, or switch statement.
+Action::OwningExprResult Sema::CheckConditionVariable(VarDecl *ConditionVar) {
+  QualType T = ConditionVar->getType();
+  
+  // C++ [stmt.select]p2:
+  //   The declarator shall not specify a function or an array.
+  if (T->isFunctionType())
+    return ExprError(Diag(ConditionVar->getLocation(), 
+                          diag::err_invalid_use_of_function_type)
+                       << ConditionVar->getSourceRange());
+  else if (T->isArrayType())
+    return ExprError(Diag(ConditionVar->getLocation(), 
+                          diag::err_invalid_use_of_array_type)
+                     << ConditionVar->getSourceRange());
+  
+  return Owned(DeclRefExpr::Create(Context, 0, SourceRange(), ConditionVar,
+                                   ConditionVar->getLocation(), 
+                                ConditionVar->getType().getNonReferenceType()));
+}
+
 /// CheckCXXBooleanCondition - Returns true if a conversion to bool is invalid.
 bool Sema::CheckCXXBooleanCondition(Expr *&CondExpr) {
   // C++ 6.4p4:
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index ad3376b9c82..cecc9b32c10 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -242,8 +242,17 @@ Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal,
   OwningExprResult CondResult(CondVal.release());
 
   Expr *condExpr = CondResult.takeAs<Expr>();
-
   assert(condExpr && "ActOnIfStmt(): missing expression");
+  
+  VarDecl *ConditionVar = 0;
+  if (CXXConditionDeclExpr *Cond = dyn_cast<CXXConditionDeclExpr>(condExpr)) {
+    ConditionVar = Cond->getVarDecl();
+    condExpr = DeclRefExpr::Create(Context, 0, SourceRange(), ConditionVar,
+                                   ConditionVar->getLocation(), 
+                                 ConditionVar->getType().getNonReferenceType());
+    // FIXME: Leaks the old condExpr
+  }
+  
   if (CheckBooleanCondition(condExpr, IfLoc)) {
     CondResult = condExpr;
     return StmtError();
@@ -265,7 +274,7 @@ Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal,
   DiagnoseUnusedExprResult(elseStmt);
 
   CondResult.release();
-  return Owned(new (Context) IfStmt(IfLoc, condExpr, thenStmt,
+  return Owned(new (Context) IfStmt(IfLoc, ConditionVar, condExpr, thenStmt,
                                     ElseLoc, elseStmt));
 }
 
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index ecac31a3e7a..d226c1eb5c2 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -3084,10 +3084,22 @@ template<typename Derived>
 Sema::OwningStmtResult
 TreeTransform<Derived>::TransformIfStmt(IfStmt *S) {
   // Transform the condition
-  OwningExprResult Cond = getDerived().TransformExpr(S->getCond());
+  OwningExprResult Cond(SemaRef);
+  VarDecl *ConditionVar = 0;
+  if (S->getConditionVariable()) {
+    ConditionVar 
+      = cast_or_null<VarDecl>(
+                   getDerived().TransformDefinition(S->getConditionVariable()));
+    if (!ConditionVar)
+      return SemaRef.StmtError();
+    
+    Cond = getSema().CheckConditionVariable(ConditionVar);
+  } else
+    Cond = getDerived().TransformExpr(S->getCond());
+  
   if (Cond.isInvalid())
     return SemaRef.StmtError();
-
+  
   Sema::FullExprArg FullCond(getSema().FullExpr(Cond));
 
   // Transform the "then" branch.