Several improvements from Doug Gregor related to default
argument handling. I'll fix up the c89 (void) thing next.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@49459 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index e7bf7bf..3211e22 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -14,11 +14,79 @@
#include "Sema.h"
#include "clang/Basic/LangOptions.h"
#include "clang/AST/Expr.h"
+#include "clang/AST/StmtVisitor.h"
#include "clang/AST/Type.h"
#include "llvm/ADT/OwningPtr.h"
+#include "llvm/Support/Compiler.h"
using namespace clang;
+//===----------------------------------------------------------------------===//
+// CheckDefaultArgumentVisitor
+//===----------------------------------------------------------------------===//
+
+/// CheckDefaultArgumentVisitor - Traverses the default argument of a
+/// parameter to determine whether it contains any ill-formed
+/// subexpressions. For example, this will diagnose the use of local
+/// variables or parameters within the default argument expression.
+class VISIBILITY_HIDDEN CheckDefaultArgumentVisitor
+ : public StmtVisitor<CheckDefaultArgumentVisitor, bool>
+{
+ Sema *S;
+
+public:
+ explicit CheckDefaultArgumentVisitor(Sema *s) : S(s) {}
+
+ bool VisitExpr(Expr *Node);
+ bool VisitDeclRefExpr(DeclRefExpr *DRE);
+};
+
+/// VisitExpr - Visit all of the children of this expression.
+bool CheckDefaultArgumentVisitor::VisitExpr(Expr *Node) {
+ bool IsInvalid = false;
+ for (Stmt::child_iterator first = Node->child_begin(),
+ last = Node->child_end();
+ first != last; ++first)
+ IsInvalid |= Visit(*first);
+
+ return IsInvalid;
+}
+
+/// VisitDeclRefExpr - Visit a reference to a declaration, to
+/// determine whether this declaration can be used in the default
+/// argument expression.
+bool CheckDefaultArgumentVisitor::VisitDeclRefExpr(DeclRefExpr *DRE) {
+ ValueDecl *Decl = DRE->getDecl();
+ if (ParmVarDecl *Param = dyn_cast<ParmVarDecl>(Decl)) {
+ // C++ [dcl.fct.default]p9
+ // Default arguments are evaluated each time the function is
+ // called. The order of evaluation of function arguments is
+ // unspecified. Consequently, parameters of a function shall not
+ // be used in default argument expressions, even if they are not
+ // evaluated. Parameters of a function declared before a default
+ // argument expression are in scope and can hide namespace and
+ // class member names.
+ return S->Diag(DRE->getSourceRange().getBegin(),
+ diag::err_param_default_argument_references_param,
+ Param->getName());
+ } else if (BlockVarDecl *BlockVar = dyn_cast<BlockVarDecl>(Decl)) {
+ // C++ [dcl.fct.default]p7
+ // Local variables shall not be used in default argument
+ // expressions.
+ return S->Diag(DRE->getSourceRange().getBegin(),
+ diag::err_param_default_argument_references_local,
+ BlockVar->getName());
+ }
+
+ // FIXME: when Clang has support for member functions, "this"
+ // will also need to be diagnosted.
+
+ return false;
+}
+
+/// ActOnParamDefaultArgument - Check whether the default argument
+/// provided for a function parameter is well-formed. If so, attach it
+/// to the parameter declaration.
void
Sema::ActOnParamDefaultArgument(DeclTy *param, SourceLocation EqualLoc,
ExprTy *defarg) {
@@ -66,6 +134,11 @@
// parameter-declaration-clause, it shall not occur within a
// declarator or abstract-declarator of a parameter-declaration.
+ // Check that the default argument is well-formed
+ CheckDefaultArgumentVisitor DefaultArgChecker(this);
+ if (DefaultArgChecker.Visit(DefaultArg.get()))
+ return;
+
// Okay: add the default argument to the parameter
Param->setDefaultArg(DefaultArg.take());
}