On 11/29/2017 03:32 PM, Jakub Jelinek wrote:
Hi!
If tsize doesn't fit into uhwi, then it obviously can't match the number of
identifiers in the structured binding declaration. While we could use
compare_tree_int and avoid that way this conversion to uhwi (though,
compare_tree_int does that anyway), for the normal uhwi case we have special
cases in cnt_mismatch shared by the other kinds of structured bindings
that handle smaller and larger cases separately, so I think it is better
to do it this way.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2017-11-29 Jakub Jelinek <ja...@redhat.com>
PR c++/83205
* decl.c (cp_finish_decomp): Handle the case when tsize is not
error_mark_node, but doesn't fit into uhwi.
* g++.dg/cpp1z/decomp32.C: New test.
--- gcc/cp/decl.c.jj 2017-11-28 22:23:34.000000000 +0100
+++ gcc/cp/decl.c 2017-11-29 15:00:24.487658715 +0100
@@ -7518,6 +7518,12 @@ cp_finish_decomp (tree decl, tree first,
"constant expression", type);
goto error_out;
}
+ if (!tree_fits_uhwi_p (tsize))
+ {
+ error_at (loc, "%u names provided while %qT decomposes into "
When count is 1 as in the test below the error isn't grammatically
correct ("1 names"). I see that the same message is already issued
elsewhere in the function so this seems like an opportunity to use
the right form here and also fix the other one at the same time or
in a followup. The error_n function exists to issue the right form
for the language, singular or plural. It's not as convenient when
the sentence contains two terms that may be singular or plural,
but that can also be dealt with.
Martin
+ "%E elements", count, type, tsize);
+ goto error_out;
+ }
eltscnt = tree_to_uhwi (tsize);
if (count != eltscnt)
goto cnt_mismatch;
--- gcc/testsuite/g++.dg/cpp1z/decomp32.C.jj 2017-11-29 15:08:59.215378903
+0100
+++ gcc/testsuite/g++.dg/cpp1z/decomp32.C 2017-11-29 15:10:31.576244649
+0100
@@ -0,0 +1,24 @@
+// PR c++/83205
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+struct A { int i; };
+struct B { int i; };
+namespace std {
+ template <typename T> struct tuple_size;
+ template <> struct tuple_size<A> {
+ static constexpr int value = -1;
+ };
+#ifdef __SIZEOF_INT128__
+ template <> struct tuple_size<B> {
+ static constexpr unsigned __int128 value = -1;
+ };
+#endif
+}
+
+auto [a] = A{}; // { dg-error "1 names provided while 'A' decomposes into -1
elements" }
+ // { dg-warning "structured bindings only available with" "" {
target c++14_down } .-1 }
+#ifdef __SIZEOF_INT128__
+auto [b] = B{}; // { dg-error "1 names provided while 'B' decomposes into
\[0-9xa-fXA-F]* elements" "" { target int128 } }
+ // { dg-warning "structured bindings only available with" "" { target {
c++14_down && int128 } } .-1 }
+#endif
Jakub
