In C++11 mode, when an integral constant expression is desired and we have a

value of class type, look for a unique conversion operator converting to
integral or unscoped enumeration type and use that. Implements [expr.const]p5.

Sema::VerifyIntegerConstantExpression now performs the conversion and returns
the converted result. Some important callers of Expr::isIntegralConstantExpr
have been switched over to using it (including all of those required for C++11
conformance); this switch brings a side-benefit of improved diagnostics and, in
several cases, simpler code. However, some language extensions and attributes
have not been moved across and will not perform implicit conversions on
constant expressions of literal class type where an ICE is required.

In passing, fix static_assert to perform a contextual conversion to bool on its
argument.

llvm-svn: 149776

1 files changed, 23 insertions, 19 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 0e5e6781a68..b68591ae93d 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -8465,9 +8465,10 @@ void Sema::ActOnTagDefinitionError(Scope *S, Decl *TagD) {
 }
 
 // Note that FieldName may be null for anonymous bitfields.
-bool Sema::VerifyBitField(SourceLocation FieldLoc, IdentifierInfo *FieldName,
-                          QualType FieldTy, const Expr *BitWidth,
-                          bool *ZeroWidth) {
+ExprResult Sema::VerifyBitField(SourceLocation FieldLoc,
+                                IdentifierInfo *FieldName,
+                                QualType FieldTy, Expr *BitWidth,
+                                bool *ZeroWidth) {
   // Default to true; that shouldn't confuse checks for emptiness
   if (ZeroWidth)
     *ZeroWidth = true;
@@ -8477,7 +8478,7 @@ bool Sema::VerifyBitField(SourceLocation FieldLoc, IdentifierInfo *FieldName,
   if (!FieldTy->isDependentType() && !FieldTy->isIntegralOrEnumerationType()) {
     // Handle incomplete types with specific error.
     if (RequireCompleteType(FieldLoc, FieldTy, diag::err_field_incomplete))
-      return true;
+      return ExprError();
     if (FieldName)
       return Diag(FieldLoc, diag::err_not_integral_type_bitfield)
         << FieldName << FieldTy << BitWidth->getSourceRange();
@@ -8485,16 +8486,18 @@ bool Sema::VerifyBitField(SourceLocation FieldLoc, IdentifierInfo *FieldName,
       << FieldTy << BitWidth->getSourceRange();
   } else if (DiagnoseUnexpandedParameterPack(const_cast<Expr *>(BitWidth),
                                              UPPC_BitFieldWidth))
-    return true;
+    return ExprError();
 
   // If the bit-width is type- or value-dependent, don't try to check
   // it now.
   if (BitWidth->isValueDependent() || BitWidth->isTypeDependent())
-    return false;
+    return Owned(BitWidth);
 
   llvm::APSInt Value;
-  if (VerifyIntegerConstantExpression(BitWidth, &Value))
-    return true;
+  ExprResult ICE = VerifyIntegerConstantExpression(BitWidth, &Value);
+  if (ICE.isInvalid())
+    return ICE;
+  BitWidth = ICE.take();
 
   if (Value != 0 && ZeroWidth)
     *ZeroWidth = false;
@@ -8534,7 +8537,7 @@ bool Sema::VerifyBitField(SourceLocation FieldLoc, IdentifierInfo *FieldName,
     }
   }
 
-  return false;
+  return Owned(BitWidth);
 }
 
 /// ActOnField - Each field of a C struct/union is passed into this in order
@@ -8700,11 +8703,13 @@ FieldDecl *Sema::CheckFieldDecl(DeclarationName Name, QualType T,
 
   bool ZeroWidth = false;
   // If this is declared as a bit-field, check the bit-field.
-  if (!InvalidDecl && BitWidth &&
-      VerifyBitField(Loc, II, T, BitWidth, &ZeroWidth)) {
-    InvalidDecl = true;
-    BitWidth = 0;
-    ZeroWidth = false;
+  if (!InvalidDecl && BitWidth) {
+    BitWidth = VerifyBitField(Loc, II, T, BitWidth, &ZeroWidth).take();
+    if (!BitWidth) {
+      InvalidDecl = true;
+      BitWidth = 0;
+      ZeroWidth = false;
+    }
   }
 
   // Check that 'mutable' is consistent with the type of the declaration.
@@ -9027,10 +9032,9 @@ Decl *Sema::ActOnIvar(Scope *S,
 
   if (BitWidth) {
     // 6.7.2.1p3, 6.7.2.1p4
-    if (VerifyBitField(Loc, II, T, BitWidth)) {
+    BitWidth = VerifyBitField(Loc, II, T, BitWidth).take();
+    if (!BitWidth)
       D.setInvalidType();
-      BitWidth = 0;
-    }
   } else {
     // Not a bitfield.
 
@@ -9591,9 +9595,9 @@ EnumConstantDecl *Sema::CheckEnumConstant(EnumDecl *Enum,
         else
           Val = Converted.take();
       } else if (!Val->isValueDependent() &&
-                 VerifyIntegerConstantExpression(Val, &EnumVal)) {
+                 !(Val = VerifyIntegerConstantExpression(Val,
+                                                         &EnumVal).take())) {
         // C99 6.7.2.2p2: Make sure we have an integer constant expression.
-        Val = 0;
       } else {
         if (!getLangOptions().CPlusPlus) {
           // C99 6.7.2.2p2: