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Implement P0036R0: remove support for empty unary folds of +, *, |, &. 

llvm-svn: 262747
This commit is contained in:
Richard Smith 2016-03-04 21:27:21 +00:00
parent b89f0fa2a2
commit 8ee39e31bb
3 changed files with 9 additions and 23 deletions
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15
clang/lib/Sema/SemaTemplateVariadic.cpp
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@ -996,10 +996,6 @@ ExprResult Sema::BuildEmptyCXXFoldExpr(SourceLocation EllipsisLoc,
BinaryOperatorKind Operator) {
// [temp.variadic]p9:
// If N is zero for a unary fold-expression, the value of the expression is
// * -> 1
// + -> int()
// & -> -1
// | -> int()
// && -> true
// || -> false
// , -> void()
@ -1009,17 +1005,6 @@ ExprResult Sema::BuildEmptyCXXFoldExpr(SourceLocation EllipsisLoc,
// prevent the result from being a null pointer constant.
QualType ScalarType;
switch (Operator) {
case BO_Add:
ScalarType = Context.IntTy;
break;
case BO_Mul:
return ActOnIntegerConstant(EllipsisLoc, 1);
case BO_Or:
ScalarType = Context.IntTy;
break;
case BO_And:
return CreateBuiltinUnaryOp(EllipsisLoc, UO_Minus,
ActOnIntegerConstant(EllipsisLoc, 1).get());
case BO_LOr:
return ActOnCXXBoolLiteral(EllipsisLoc, tok::kw_false);
case BO_LAnd:

15
clang/test/SemaTemplate/cxx1z-fold-expressions.cpp
View File

@ -25,10 +25,6 @@ constexpr bool check() {
static_assert(check());
template<int ...N> void empty() {
static_assert((N + ...) == 0);
static_assert((N * ...) == 1);
static_assert((N | ...) == 0);
static_assert((N & ...) == -1);
static_assert((N || ...) == false);
static_assert((N && ...) == true);
(N, ...);
@ -36,14 +32,19 @@ template<int ...N> void empty() {
template void empty<>();
// An empty fold-expression isn't a null pointer just because it's an integer
// with value 0.
// with value 0. (This is no longer an issue since empty pack expansions don't
// produce integers any more.)
template<int ...N> void null_ptr() {
void *p = (N + ...); // expected-error {{rvalue of type 'int'}}
void *q = (N | ...); // expected-error {{rvalue of type 'int'}}
void *p = (N || ...); // expected-error {{rvalue of type 'bool'}}
void *q = (N , ...); // expected-error {{rvalue of type 'void'}}
}
template void null_ptr<>(); // expected-note {{in instantiation of}}
template<int ...N> void bad_empty() {
(N + ...); // expected-error {{empty expansion for operator '+' with no fallback}}
(N * ...); // expected-error {{empty expansion for operator '*' with no fallback}}
(N | ...); // expected-error {{empty expansion for operator '|' with no fallback}}
(N & ...); // expected-error {{empty expansion for operator '&' with no fallback}}
(N - ...); // expected-error {{empty expansion for operator '-' with no fallback}}
(N / ...); // expected-error {{empty expansion for operator '/' with no fallback}}
(N % ...); // expected-error {{empty expansion for operator '%' with no fallback}}

2
clang/www/cxx_status.html
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@ -577,7 +577,7 @@ as the draft C++1z standard evolves.</p>
</tr>
<tr> <!-- from Jacksonville -->
<td><a href="http://wg21.link/p0036r0">P0036R0</a></td>
<td class="no" align="center">No</td>
<td class="svn" align="center">SVN</td>
</tr>
<tr>
<td><tt>u8</tt> character literals</td>