Mordante updated this revision to Diff 215448.
Mordante added a comment.
Updated the unit tests as requested. This required the
`Sema::ActOnParamDefaultArgument` to delay a part of the ODR validation until
the default argument has been 'instantiated'.
As discussed on IRC; the up to date `cwg_index.html` is not public, so I only
updated the unit test and removed the changes to `cxx_dr_status.html`.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D65696/new/
https://reviews.llvm.org/D65696
Files:
clang/lib/Sema/SemaDeclCXX.cpp
clang/test/CXX/dcl.decl/dcl.fct.def/dcl.fct.def.default/p9.cpp
clang/test/CXX/dcl.decl/dcl.meaning/dcl.fct.default/p7.cpp
clang/test/CXX/drs/dr20xx.cpp
Index: clang/test/CXX/drs/dr20xx.cpp
===================================================================
--- clang/test/CXX/drs/dr20xx.cpp
+++ clang/test/CXX/drs/dr20xx.cpp
@@ -8,6 +8,76 @@
#define static_assert(...) _Static_assert(__VA_ARGS__)
#endif
+
+namespace dr2082 { // dr2082: 10
+namespace local_var {
+void g() {
+ int k = 42;
+ void l(int m = k); // expected-error {{default argument references local variable 'k' of enclosing function}}
+}
+} // namespace local_var
+namespace local_const {
+void g() {
+ const int k = 42;
+ void l(int m = k);
+}
+} // namespace local_const
+#if __cplusplus >= 201103L
+namespace local_constexpr {
+void g() {
+ constexpr int k = 42;
+ void l(int m = k);
+}
+} // namespace local_constexpr
+#endif
+
+namespace local_const_float_to_integral {
+void g() {
+ const double k = 42;
+ void l(int m = k); // expected-error {{default argument references local variable 'k' of enclosing function}}
+}
+} // namespace local_const_float_to_integral
+#if __cplusplus >= 201103L
+namespace local_constexpr_float_to_integral {
+void g() {
+ constexpr double k = 42;
+ void l(int m = k);
+}
+} // namespace local_constexpr_float_to_integral
+
+namespace local_member_const {
+struct a {
+ int b;
+ int c;
+};
+void g() {
+ const a n{42, 42};
+ void l(int m = n.b); // expected-error {{default argument references local variable 'n' of enclosing function}}
+}
+} // namespace local_member_const
+namespace local_member_constexpr {
+struct a {
+ int b;
+ int c;
+};
+void g() {
+ constexpr a n{42, 42};
+ void l(int m = n.b);
+}
+} // namespace local_member_constexpr
+namespace local_member_mutable {
+struct a {
+ int b;
+ mutable int c;
+};
+void g() {
+ constexpr a n{42, 42};
+ void l(int m = n.b); // expected-error {{default argument references local variable 'n' of enclosing function}}
+}
+} // namespace local_member_mutable
+#endif
+}
+
namespace dr2083 { // dr2083: partial
#if __cplusplus >= 201103L
void non_const_mem_ptr() {
Index: clang/test/CXX/dcl.decl/dcl.meaning/dcl.fct.default/p7.cpp
===================================================================
--- clang/test/CXX/dcl.decl/dcl.meaning/dcl.fct.default/p7.cpp
+++ clang/test/CXX/dcl.decl/dcl.meaning/dcl.fct.default/p7.cpp
@@ -1,7 +1,8 @@
// RUN: %clang_cc1 -fsyntax-only -verify %s
-void h()
+void f()
{
int i;
- extern void h2(int x = sizeof(i)); // expected-error {{default argument references local variable 'i' of enclosing function}}
+ extern void g(int x = i); // expected-error {{default argument references local variable 'i' of enclosing function}}
+ extern void h(int x = sizeof(i));
}
Index: clang/test/CXX/dcl.decl/dcl.fct.def/dcl.fct.def.default/p9.cpp
===================================================================
--- /dev/null
+++ clang/test/CXX/dcl.decl/dcl.fct.def/dcl.fct.def.default/p9.cpp
@@ -0,0 +1,23 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+int a;
+int f(int a, int b = a); // expected-error {{default argument references parameter 'a'}}
+typedef int I;
+int g(float I, int b = I(2)); // expected-error {{called object type 'float' is not a function or function pointer}}
+int h(int a, int b = sizeof(a));
+
+int b;
+class X {
+ int a;
+ int mem1(int i = a); // expected-error {{invalid use of non-static data member 'a'}}
+ int mem2(int i = b);
+ static int b;
+};
+
+int f(int = 0);
+void h() {
+ int j = f(1);
+ int k = f();
+}
+int (*p1)(int) = &f;
+int (*p2)() = &f; // expected-error {{cannot initialize a variable of type 'int (*)()' with an rvalue of type 'int (*)(int)': different number of parameters (0 vs 1)}}
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -86,29 +86,22 @@
NamedDecl *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.
+ // A default argument is evaluated each time the function is called
+ // with no argument for the corresponding parameter. A parameter shall
+ // not appear as a potentially-evaluated expression in a default
+ // argument. Parameters of a function declared before a default
+ // argument are in scope and can hide namespace and class member
+ // names.
+ if (DRE->isNonOdrUse() == NOUR_Unevaluated)
+ return false;
+
return S->Diag(DRE->getBeginLoc(),
diag::err_param_default_argument_references_param)
<< Param->getDeclName() << DefaultArg->getSourceRange();
- } else if (VarDecl *VDecl = dyn_cast<VarDecl>(Decl)) {
- // C++ [dcl.fct.default]p7
- // Local variables shall not be used in default argument
- // expressions.
- if (VDecl->isLocalVarDecl())
- return S->Diag(DRE->getBeginLoc(),
- diag::err_param_default_argument_references_local)
- << VDecl->getDeclName() << DefaultArg->getSourceRange();
}
return false;
}
-
/// VisitCXXThisExpr - Visit a C++ "this" expression.
bool CheckDefaultArgumentVisitor::VisitCXXThisExpr(CXXThisExpr *ThisE) {
// C++ [dcl.fct.default]p8:
@@ -147,6 +140,60 @@
}
}
+ /// CheckDefaultArgumentVisitorODR - C++ [dcl.fct.default] Traverses
+ /// the default argument of a parameter to determine whether it
+ /// contains ODR violations. These violations cannot be checked in
+ /// \ref CheckDefaultArgumentVisitor since the DeclRefExp's may be changed to
+ /// an implicit cast from an LValue to RValue by \ref SetParamDefaultArgument.
+ /// When that happens the ODR usage may be allowed.
+ class CheckDefaultArgumentVisitorODR
+ : public StmtVisitor<CheckDefaultArgumentVisitorODR, bool> {
+ Expr *DefaultArg;
+ Sema *S;
+
+ public:
+ CheckDefaultArgumentVisitorODR(Expr *defarg, Sema *s)
+ : DefaultArg(defarg), S(s) {}
+
+ bool VisitExpr(Expr *Node);
+ bool VisitDeclRefExpr(DeclRefExpr *DRE);
+ };
+
+ /// VisitExpr - Visit all of the children of this expression.
+ bool CheckDefaultArgumentVisitorODR::VisitExpr(Expr *Node) {
+ bool IsInvalid = false;
+ for (Stmt *SubStmt : Node->children())
+ IsInvalid |= Visit(SubStmt);
+ return IsInvalid;
+ }
+
+ /// VisitDeclRefExpr - Visit a reference to a declaration, to determine
+ /// whether this declaration can be used in the default argument expression.
+ bool CheckDefaultArgumentVisitorODR::VisitDeclRefExpr(DeclRefExpr *DRE) {
+ NamedDecl *Decl = DRE->getDecl();
+
+ if (VarDecl *VDecl = dyn_cast<VarDecl>(Decl)) {
+ // C++ [dcl.fct.default]p7
+ // A local variable cannot be odr-used (6.2) in a default argument.
+ // C++2a [basic.def.odr]p4:
+ // A variable x whose name appears as a potentially-evalauted expression
+ // e is odr-used by e unless [...]
+ // -- x is a variable of non-reference type that is usable in constant
+ // expressions and has no mutable subobjects, and e is an element of
+ // the set of potential results of an expression of
+ // non-volatile-qualified non-class type to which the
+ // lvalue-to-rvalue conversion is applied, or
+ if (DRE->isNonOdrUse() != NOUR_None)
+ return false;
+
+ if (VDecl->isLocalVarDecl())
+ return S->Diag(DRE->getBeginLoc(),
+ diag::err_param_default_argument_references_local)
+ << VDecl->getDeclName() << DefaultArg->getSourceRange();
+ }
+ return false;
+ }
+
void
Sema::ImplicitExceptionSpecification::CalledDecl(SourceLocation CallLoc,
const CXXMethodDecl *Method) {
@@ -333,7 +380,11 @@
return;
}
- SetParamDefaultArgument(Param, DefaultArg, EqualLoc);
+ if (!SetParamDefaultArgument(Param, DefaultArg, EqualLoc)) {
+ CheckDefaultArgumentVisitorODR DefaultArgCheckerODR(DefaultArg, this);
+ if (DefaultArgCheckerODR.Visit(Param->getDefaultArg()))
+ Param->setInvalidDecl();
+ }
}
/// ActOnParamUnparsedDefaultArgument - We've seen a default
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