On Wed, Jun 27, 2018 at 07:35:15PM -0400, Jason Merrill wrote:
> On Wed, Jun 27, 2018 at 12:53 PM, Marek Polacek <pola...@redhat.com> wrote:
> > This PR complains about us accepting invalid code like
> >
> > template<unsigned int> struct A {};
> > A<-1> a;
> >
> > Where we should detect the narrowing: [temp.arg.nontype] says
> > "A template-argument for a non-type template-parameter shall be a converted
> > constant expression ([expr.const]) of the type of the template-parameter."
> > and a converted constant expression can contain only
> > - integral conversions other than narrowing conversions,
> > - [...]."
> > It spurred e.g.
> > <https://stackoverflow.com/questions/28184888/how-implicit-conversion-works-for-non-type-template-parameters>
> > and has >=3 dups so it has some visibility.
> >
> > I think build_converted_constant_expr needs to set check_narrowing.
> > check_narrowing also always mentions that it's in { } but that is no longer
> > true; in the future it will also apply to <=>. We'd probably have to add a
> > new
> > flag to struct conversion if wanted to distinguish between these.
> >
> > This does not yet fix detecting narrowing in function templates (78244).
> >
> > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> >
> > 2018-06-27 Marek Polacek <pola...@redhat.com>
> >
> > PR c++/57891
> > * call.c (build_converted_constant_expr): Set check_narrowing.
> > * decl.c (compute_array_index_type): Add warning sentinel. Use
> > input_location.
> > * pt.c (convert_nontype_argument): Return NULL_TREE if any errors
> > were reported.
> > * typeck2.c (check_narrowing): Don't mention { } in diagnostic.
> >
> > * g++.dg/cpp0x/Wnarrowing6.C: New test.
> > * g++.dg/cpp0x/Wnarrowing7.C: New test.
> > * g++.dg/cpp0x/Wnarrowing8.C: New test.
> > * g++.dg/cpp0x/constexpr-data2.C: Add dg-error.
> > * g++.dg/init/new43.C: Adjust dg-error.
> > * g++.dg/other/fold1.C: Likewise.
> > * g++.dg/parse/array-size2.C: Likewise.
> > * g++.dg/other/vrp1.C: Add dg-error.
> > * g++.dg/template/char1.C: Likewise.
> > * g++.dg/ext/builtin12.C: Likewise.
> > * g++.dg/template/dependent-name3.C: Adjust dg-error.
> >
> > diff --git gcc/cp/call.c gcc/cp/call.c
> > index 209c1fd2f0e..956c7b149dc 100644
> > --- gcc/cp/call.c
> > +++ gcc/cp/call.c
> > @@ -4152,7 +4152,10 @@ build_converted_constant_expr (tree type, tree expr,
> > tsubst_flags_t complain)
> > }
> >
> > if (conv)
> > - expr = convert_like (conv, expr, complain);
> > + {
> > + conv->check_narrowing = !processing_template_decl;
>
> Why !processing_template_decl? This needs a comment.
Otherwise we'd warn for e.g.
template<int N> struct S { char a[N]; };
S<1> s;
where compute_array_index_type will try to convert the size of the array (which
is a template_parm_index of type int when parsing the template) to size_type.
So I guess I can say that we need to wait for instantiation?
> > + expr = convert_like (conv, expr, complain);
> > + }
> > else
> > expr = error_mark_node;
> >
> > diff --git gcc/cp/pt.c gcc/cp/pt.c
> > index 3780f3492aa..12d1a1e1cd3 100644
> > --- gcc/cp/pt.c
> > +++ gcc/cp/pt.c
> > @@ -6669,9 +6669,10 @@ convert_nontype_argument (tree type, tree expr,
> > tsubst_flags_t complain)
> > /* C++17: A template-argument for a non-type template-parameter
> > shall
> > be a converted constant expression (8.20) of the type of the
> > template-parameter. */
> > + int errs = errorcount;
> > expr = build_converted_constant_expr (type, expr, complain);
> > if (expr == error_mark_node)
> > - return error_mark_node;
> > + return errorcount > errs ? NULL_TREE : error_mark_node;
>
> I suspect that what you want here is to check (complain & tf_error)
> rather than errorcount. Otherwise it needs a comment.
I added a comment. Checking complain doesn't work becase that doesn't
say if we have really issued an error. If we have not, and we return
NULL_TREE anyway, we hit this assert:
8515 if (lost)
8516 {
8517 gcc_assert (!(complain & tf_error) || seen_error ());
8518 return error_mark_node;
8519 }
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2018-06-29 Marek Polacek <pola...@redhat.com>
PR c++/57891
* call.c (build_converted_constant_expr): Set check_narrowing.
* decl.c (compute_array_index_type): Add warning sentinel. Use
input_location.
* pt.c (convert_nontype_argument): Return NULL_TREE if any errors
were reported.
* typeck2.c (check_narrowing): Don't mention { } in diagnostic.
* g++.dg/cpp0x/Wnarrowing6.C: New test.
* g++.dg/cpp0x/Wnarrowing7.C: New test.
* g++.dg/cpp0x/Wnarrowing8.C: New test.
* g++.dg/cpp0x/constexpr-data2.C: Add dg-error.
* g++.dg/init/new43.C: Adjust dg-error.
* g++.dg/other/fold1.C: Likewise.
* g++.dg/parse/array-size2.C: Likewise.
* g++.dg/other/vrp1.C: Add dg-error.
* g++.dg/template/char1.C: Likewise.
* g++.dg/ext/builtin12.C: Likewise.
* g++.dg/template/dependent-name3.C: Adjust dg-error.
diff --git gcc/cp/call.c gcc/cp/call.c
index 209c1fd2f0e..3e7988e0358 100644
--- gcc/cp/call.c
+++ gcc/cp/call.c
@@ -4152,7 +4152,12 @@ build_converted_constant_expr (tree type, tree expr,
tsubst_flags_t complain)
}
if (conv)
- expr = convert_like (conv, expr, complain);
+ {
+ /* Only check the narrowing at instantiation time, otherwise
+ we'd emit bogus warnings for template trees. */
+ conv->check_narrowing = !processing_template_decl;
+ expr = convert_like (conv, expr, complain);
+ }
else
expr = error_mark_node;
diff --git gcc/cp/decl.c gcc/cp/decl.c
index c04b9b7d457..8da63fa2aaa 100644
--- gcc/cp/decl.c
+++ gcc/cp/decl.c
@@ -9508,6 +9508,8 @@ compute_array_index_type (tree name, tree size,
tsubst_flags_t complain)
else
{
size = instantiate_non_dependent_expr_sfinae (size, complain);
+ /* Don't warn about narrowing for VLAs. */
+ warning_sentinel s (warn_narrowing, !TREE_CONSTANT (osize));
size = build_converted_constant_expr (size_type_node, size, complain);
size = maybe_constant_value (size);
@@ -9556,7 +9558,7 @@ compute_array_index_type (tree name, tree size,
tsubst_flags_t complain)
{
tree folded = cp_fully_fold (size);
if (TREE_CODE (folded) == INTEGER_CST)
- pedwarn (location_of (size), OPT_Wpedantic,
+ pedwarn (input_location, OPT_Wpedantic,
"size of array is not an integral constant-expression");
/* Use the folded result for VLAs, too; it will have resolved
SIZEOF_EXPR. */
diff --git gcc/cp/pt.c gcc/cp/pt.c
index 3780f3492aa..25b71a75c5f 100644
--- gcc/cp/pt.c
+++ gcc/cp/pt.c
@@ -6669,9 +6669,12 @@ convert_nontype_argument (tree type, tree expr,
tsubst_flags_t complain)
/* C++17: A template-argument for a non-type template-parameter shall
be a converted constant expression (8.20) of the type of the
template-parameter. */
+ int errs = errorcount;
expr = build_converted_constant_expr (type, expr, complain);
if (expr == error_mark_node)
- return error_mark_node;
+ /* Make sure we return NULL_TREE only if we have really issued
+ an error, as described above. */
+ return errorcount > errs ? NULL_TREE : error_mark_node;
expr = maybe_constant_value (expr);
expr = convert_from_reference (expr);
}
diff --git gcc/cp/typeck2.c gcc/cp/typeck2.c
index 91aa5a62856..d82e3b608da 100644
--- gcc/cp/typeck2.c
+++ gcc/cp/typeck2.c
@@ -875,7 +875,8 @@ store_init_value (tree decl, tree init, vec<tree, va_gc>**
cleanups, int flags)
}
-/* Give diagnostic about narrowing conversions within { }. */
+/* Give diagnostic about narrowing conversions within { }, or as part of
+ a converted constant expression. */
bool
check_narrowing (tree type, tree init, tsubst_flags_t complain)
@@ -967,7 +968,7 @@ check_narrowing (tree type, tree init, tsubst_flags_t
complain)
{
if (complain & tf_warning)
warning_at (loc, OPT_Wnarrowing, "narrowing conversion of %qE "
- "from %qH to %qI inside { } is ill-formed in C++11",
+ "from %qH to %qI is ill-formed in C++11",
init, ftype, type);
ok = true;
}
@@ -977,8 +978,7 @@ check_narrowing (tree type, tree init, tsubst_flags_t
complain)
{
if ((!almost_ok || pedantic)
&& pedwarn (loc, OPT_Wnarrowing,
- "narrowing conversion of %qE "
- "from %qH to %qI inside { }",
+ "narrowing conversion of %qE from %qH to %qI",
init, ftype, type)
&& almost_ok)
inform (loc, " the expression has a constant value but is not "
@@ -991,8 +991,8 @@ check_narrowing (tree type, tree init, tsubst_flags_t
complain)
int savederrorcount = errorcount;
global_dc->pedantic_errors = 1;
pedwarn (loc, OPT_Wnarrowing,
- "narrowing conversion of %qE from %qH to %qI "
- "inside { }", init, ftype, type);
+ "narrowing conversion of %qE from %qH to %qI ",
+ init, ftype, type);
if (errorcount == savederrorcount)
ok = true;
global_dc->pedantic_errors = flag_pedantic_errors;
diff --git gcc/testsuite/g++.dg/cpp0x/Wnarrowing6.C
gcc/testsuite/g++.dg/cpp0x/Wnarrowing6.C
index e69de29bb2d..989d277cd00 100644
--- gcc/testsuite/g++.dg/cpp0x/Wnarrowing6.C
+++ gcc/testsuite/g++.dg/cpp0x/Wnarrowing6.C
@@ -0,0 +1,8 @@
+// PR c++/57891
+// { dg-do compile { target c++11 } }
+
+template<unsigned int> struct A {};
+A<-1> a; // { dg-error "narrowing conversion" }
+
+template<signed char> struct B {};
+B<1000> b; // { dg-error "narrowing conversion" }
diff --git gcc/testsuite/g++.dg/cpp0x/Wnarrowing7.C
gcc/testsuite/g++.dg/cpp0x/Wnarrowing7.C
index e69de29bb2d..099fdfb7d81 100644
--- gcc/testsuite/g++.dg/cpp0x/Wnarrowing7.C
+++ gcc/testsuite/g++.dg/cpp0x/Wnarrowing7.C
@@ -0,0 +1,9 @@
+// PR c++/57891
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wno-narrowing" }
+
+template<unsigned int> struct A {};
+A<-1> a;
+
+template<signed char> struct B {};
+B<1000> b; // { dg-warning "overflow" }
diff --git gcc/testsuite/g++.dg/cpp0x/Wnarrowing8.C
gcc/testsuite/g++.dg/cpp0x/Wnarrowing8.C
index e69de29bb2d..39c924c9c6c 100644
--- gcc/testsuite/g++.dg/cpp0x/Wnarrowing8.C
+++ gcc/testsuite/g++.dg/cpp0x/Wnarrowing8.C
@@ -0,0 +1,6 @@
+// PR c++/57891
+// { dg-do compile { target c++11 } }
+
+struct X { constexpr operator int () { return 1000; } };
+template<signed char> struct C {};
+C<X{}> c; // { dg-error "narrowing conversion" }
diff --git gcc/testsuite/g++.dg/cpp0x/constexpr-data2.C
gcc/testsuite/g++.dg/cpp0x/constexpr-data2.C
index 898102167de..dee5ed82301 100644
--- gcc/testsuite/g++.dg/cpp0x/constexpr-data2.C
+++ gcc/testsuite/g++.dg/cpp0x/constexpr-data2.C
@@ -43,4 +43,4 @@ extern template struct A3<int, 510>;
// Use.
A3<int, 1111> a31;
-A3<char, 9999> a32; // { dg-warning "overflow" }
+A3<char, 9999> a32; // { dg-error "narrowing conversion" }
diff --git gcc/testsuite/g++.dg/ext/builtin12.C
gcc/testsuite/g++.dg/ext/builtin12.C
index 1d6bb75cd77..489b37777c4 100644
--- gcc/testsuite/g++.dg/ext/builtin12.C
+++ gcc/testsuite/g++.dg/ext/builtin12.C
@@ -5,6 +5,6 @@ template<bool> struct A {};
constexpr int foo()
{
- A<__builtin_constant_p(0)> a{};
+ A<__builtin_constant_p(0)> a{}; // { dg-error "narrowing conversion" }
return 0;
}
diff --git gcc/testsuite/g++.dg/init/new43.C gcc/testsuite/g++.dg/init/new43.C
index 9b0866720fe..7ab2a36392e 100644
--- gcc/testsuite/g++.dg/init/new43.C
+++ gcc/testsuite/g++.dg/init/new43.C
@@ -31,35 +31,35 @@ void test_literal ()
// Verify integer literal.
p = new char [-1]; // { dg-error "size of array is negative" }
- p = new char [2][-3]; // { dg-error "size of array is negative" }
+ p = new char [2][-3]; // { dg-error "size of array is
negative|narrowing conversion" }
p = new char [-4][5]; // { dg-error "size of array is negative" }
- p = new char [-6][-7]; // { dg-error "size of array is negative" }
+ p = new char [-6][-7]; // { dg-error "size of array is
negative|narrowing conversion" }
p = new (p) char [-1]; // { dg-error "size of array is negative" }
- p = new (p) char [2][-3]; // { dg-error "size of array is negative" }
+ p = new (p) char [2][-3]; // { dg-error "size of array is
negative|narrowing conversion" }
p = new (p) char [-4][5]; // { dg-error "size of array is negative" }
- p = new (p) char [-6][-7]; // { dg-error "size of array is negative" }
+ p = new (p) char [-6][-7]; // { dg-error "size of array is
negative|narrowing conversion" }
p = new (p) A [-1]; // { dg-error "size of array is negative" }
- p = new (p) A [2][-3]; // { dg-error "size of array is negative" }
+ p = new (p) A [2][-3]; // { dg-error "size of array is
negative|narrowing conversion" }
p = new (p) A [-4][5]; // { dg-error "size of array is negative" }
- p = new (p) A [-6][-7]; // { dg-error "size of array is negative" }
+ p = new (p) A [-6][-7]; // { dg-error "size of array is
negative|narrowing conversion" }
p = new (p) B [-1]; // { dg-error "size of array is negative" }
- p = new (p) B [2][-3]; // { dg-error "size of array is negative" }
+ p = new (p) B [2][-3]; // { dg-error "size of array is
negative|narrowing conversion" }
p = new (p) B [-4][5]; // { dg-error "size of array is negative" }
- p = new (p) B [-6][-7]; // { dg-error "size of array is negative" }
+ p = new (p) B [-6][-7]; // { dg-error "size of array is
negative|narrowing conversion" }
p = new (&b) B [-1]; // { dg-error "size of array is negative" }
- p = new (&b) B [2][-3]; // { dg-error "size of array is negative" }
+ p = new (&b) B [2][-3]; // { dg-error "size of array is
negative|narrowing conversion" }
p = new (&b) B [-4][5]; // { dg-error "size of array is negative" }
- p = new (&b) B [-6][-7]; // { dg-error "size of array is negative" }
+ p = new (&b) B [-6][-7]; // { dg-error "size of array is
negative|narrowing conversion" }
p = new char [1 - 2]; // { dg-error "size of array is negative" }
p = new (p) char [2 - 3]; // { dg-error "size of array is negative" }
p = new A [2 < 1 ? -1 : -2]; // { dg-error "size of array is negative" }
p = new (p) B [2 - 3 * 2]; // { dg-error "size of array is negative" }
- p = new (&b) B [1][2 - 3 * 2];// { dg-error "size of array is negative" }
+ p = new (&b) B [1][2 - 3 * 2];// { dg-error "size of array|narrowing
conversion" }
}
void test_constant_expression ()
@@ -79,35 +79,35 @@ void test_constant_expression ()
// Verify constant expression.
p = new char [i1]; // { dg-error "size of array is negative" }
- p = new char [2][i3]; // { dg-error "size of array is negative" }
+ p = new char [2][i3]; // { dg-error "size of array is|narrowing
conversion" }
p = new char [i4][5]; // { dg-error "size of array is negative" }
- p = new char [i6][i7]; // { dg-error "size of array is negative" }
+ p = new char [i6][i7]; // { dg-error "size of array is|narrowing
conversion" }
p = new (p) char [i1]; // { dg-error "size of array is negative" }
- p = new (p) char [2][i3]; // { dg-error "size of array is negative" }
+ p = new (p) char [2][i3]; // { dg-error "size of array is|narrowing
conversion" }
p = new (p) char [i4][5]; // { dg-error "size of array is negative" }
- p = new (p) char [i6][i7]; // { dg-error "size of array is negative" }
+ p = new (p) char [i6][i7]; // { dg-error "size of array is|narrowing
conversion" }
p = new (p) A [i1]; // { dg-error "size of array is negative" }
- p = new (p) A [2][i3]; // { dg-error "size of array is negative" }
+ p = new (p) A [2][i3]; // { dg-error "size of array is|narrowing
conversion" }
p = new (p) A [i4][5]; // { dg-error "size of array is negative" }
- p = new (p) A [i6][i7]; // { dg-error "size of array is negative" }
+ p = new (p) A [i6][i7]; // { dg-error "size of array is|narrowing
conversion" }
p = new (p) B [i1]; // { dg-error "size of array is negative" }
- p = new (p) B [2][i3]; // { dg-error "size of array is negative" }
+ p = new (p) B [2][i3]; // { dg-error "size of array is|narrowing
conversion" }
p = new (p) B [i4][5]; // { dg-error "size of array is negative" }
- p = new (p) B [i6][i7]; // { dg-error "size of array is negative" }
+ p = new (p) B [i6][i7]; // { dg-error "size of array is|narrowing
conversion" }
p = new (&b) B [i1]; // { dg-error "size of array is negative" }
- p = new (&b) B [2][i3]; // { dg-error "size of array is negative" }
+ p = new (&b) B [2][i3]; // { dg-error "size of array is|narrowing
conversion" }
p = new (&b) B [i4][5]; // { dg-error "size of array is negative" }
- p = new (&b) B [i6][i7]; // { dg-error "size of array is negative" }
+ p = new (&b) B [i6][i7]; // { dg-error "size of array is|narrowing
conversion" }
p = new short [i1 - 2]; // { dg-error "size of array is negative" }
p = new (p) bool [i2 - 3]; // { dg-error "size of array is negative" }
p = new A [2 < 1 ? i1 : i2]; // { dg-error "size of array is negative" }
p = new (p) B [2 + i3 * 2]; // { dg-error "size of array is negative" }
- p = new (&b) B [1][i1 - 3 * 2];// { dg-error "size of array is negative" }
+ p = new (&b) B [1][i1 - 3 * 2];// { dg-error "size of array|narrowing
conversion" }
}
void test_constexpr ()
diff --git gcc/testsuite/g++.dg/other/fold1.C gcc/testsuite/g++.dg/other/fold1.C
index 23d34546e0b..bf074038b04 100644
--- gcc/testsuite/g++.dg/other/fold1.C
+++ gcc/testsuite/g++.dg/other/fold1.C
@@ -4,5 +4,5 @@
struct A
{
static const int i = i; // { dg-error "not declared" }
- int x[i]; // { dg-error "constant-expression" }
+ int x[i]; // { dg-error "constant-expression|narrowing
conversion" }
};
diff --git gcc/testsuite/g++.dg/other/vrp1.C gcc/testsuite/g++.dg/other/vrp1.C
index 0a798c9954e..466a15b4cbb 100644
--- gcc/testsuite/g++.dg/other/vrp1.C
+++ gcc/testsuite/g++.dg/other/vrp1.C
@@ -9,4 +9,4 @@ long long mod (long long l, long long r)
return 0LL;
return l % r;
}
-template long long mod<-0x8000000000000000LL> (long long, long long);
+template long long mod<-0x8000000000000000LL> (long long, long long); // {
dg-error "template-id" "" { target { c++11 } } }
diff --git gcc/testsuite/g++.dg/parse/array-size2.C
gcc/testsuite/g++.dg/parse/array-size2.C
index d0bc47fe746..997b95eed1a 100644
--- gcc/testsuite/g++.dg/parse/array-size2.C
+++ gcc/testsuite/g++.dg/parse/array-size2.C
@@ -14,7 +14,7 @@ extern void bar (char *, char *);
void
foo (void)
{
- char g[(char *) &((struct S *) 0)->b - (char *) 0]; // { dg-error "constant"
}
+ char g[(char *) &((struct S *) 0)->b - (char *) 0]; // { dg-error
"constant|narrowing conversion" }
char h[(__SIZE_TYPE__) &((struct S *) 8)->b]; // { dg-error
"constant" }
bar (g, h);
}
diff --git gcc/testsuite/g++.dg/template/char1.C
gcc/testsuite/g++.dg/template/char1.C
index 51e72e7ad06..a6cffaaf024 100644
--- gcc/testsuite/g++.dg/template/char1.C
+++ gcc/testsuite/g++.dg/template/char1.C
@@ -1,4 +1,5 @@
template <class CharType, CharType line_terminator = 0>
class String {};
-String<signed char, 255> s; // { dg-warning "overflow" }
+String<signed char, 255> s; // { dg-error "narrowing conversion" ""
{ target c++11 } }
+// { dg-warning "overflow" "" { target c++98_only } .-1 }
diff --git gcc/testsuite/g++.dg/template/dependent-name3.C
gcc/testsuite/g++.dg/template/dependent-name3.C
index bbe6fb66266..f9d14055a11 100644
--- gcc/testsuite/g++.dg/template/dependent-name3.C
+++ gcc/testsuite/g++.dg/template/dependent-name3.C
@@ -11,7 +11,7 @@ template<int I> struct A
template<int N> struct B
{
int x[A<N>::zero]; // { dg-error "zero" }
- int y[A<N>::minus_one]; // { dg-error "negative" }
+ int y[A<N>::minus_one]; // { dg-error "size of array|narrowing conversion" }
};
B<0> b;
