https://gcc.gnu.org/g:20e31f507a2dd6cbd40cc65a7c06d07bfaa2a5e1
commit r16-6-g20e31f507a2dd6cbd40cc65a7c06d07bfaa2a5e1
Author: Jason Merrill <ja...@redhat.com>
Date: Mon Mar 24 12:59:39 2025 -0400
c++: improve pack index diagnostics
While looking at pack-indexing16.C I thought it would be helpful to print
the problematic type/value.
gcc/cp/ChangeLog:
* semantics.cc (finish_type_pack_element): Add more info
to diagnostics.
libstdc++-v3/ChangeLog:
* testsuite/20_util/tuple/element_access/get_neg.cc: Adjust
diagnostic.
gcc/testsuite/ChangeLog:
* g++.dg/cpp26/pack-indexing2.C: Adjust diagnostics.
* g++.dg/ext/type_pack_element2.C: Likewise.
* g++.dg/ext/type_pack_element4.C: Likewise.
Diff:
---
gcc/cp/semantics.cc | 18 ++++++++++++++----
gcc/testsuite/g++.dg/cpp26/pack-indexing2.C | 6 +++---
gcc/testsuite/g++.dg/ext/type_pack_element2.C | 2 +-
gcc/testsuite/g++.dg/ext/type_pack_element4.C | 2 +-
.../testsuite/20_util/tuple/element_access/get_neg.cc | 2 +-
5 files changed, 20 insertions(+), 10 deletions(-)
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index a10ef34383c2..7f23efd4a11e 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -5088,22 +5088,32 @@ static tree
finish_type_pack_element (tree idx, tree types, tsubst_flags_t complain)
{
idx = maybe_constant_value (idx, NULL_TREE, mce_true);
- if (TREE_CODE (idx) != INTEGER_CST || !INTEGRAL_TYPE_P (TREE_TYPE (idx)))
+ if (!INTEGRAL_TYPE_P (TREE_TYPE (idx)))
{
if (complain & tf_error)
- error ("pack index is not an integral constant");
+ error ("pack index has non-integral type %qT", TREE_TYPE (idx));
+ return error_mark_node;
+ }
+ if (TREE_CODE (idx) != INTEGER_CST)
+ {
+ if (complain & tf_error)
+ {
+ error ("pack index is not an integral constant");
+ cxx_constant_value (idx);
+ }
return error_mark_node;
}
if (tree_int_cst_sgn (idx) < 0)
{
if (complain & tf_error)
- error ("pack index is negative");
+ error ("pack index %qE is negative", idx);
return error_mark_node;
}
if (wi::to_widest (idx) >= TREE_VEC_LENGTH (types))
{
if (complain & tf_error)
- error ("pack index is out of range");
+ error ("pack index %qE is out of range for pack of length %qd",
+ idx, TREE_VEC_LENGTH (types));
return error_mark_node;
}
return TREE_VEC_ELT (types, tree_to_shwi (idx));
diff --git a/gcc/testsuite/g++.dg/cpp26/pack-indexing2.C
b/gcc/testsuite/g++.dg/cpp26/pack-indexing2.C
index fdc8320e2555..4a7e494ab043 100644
--- a/gcc/testsuite/g++.dg/cpp26/pack-indexing2.C
+++ b/gcc/testsuite/g++.dg/cpp26/pack-indexing2.C
@@ -49,7 +49,7 @@ template<int N>
int
getT2 (auto... Ts)
{
- return Ts...[N]; // { dg-error "pack index is negative" }
+ return Ts...[N]; // { dg-error "pack index '-1' is negative" }
}
template<auto N, typename... Ts>
@@ -63,7 +63,7 @@ template<auto N, typename... Ts>
void
badtype2 ()
{
- Ts...[N] t; // { dg-error "pack index is out of range" }
+ Ts...[N] t; // { dg-error "pack index '1' is out of range for pack of length
'1'" }
}
template<auto N, typename... Ts>
@@ -77,7 +77,7 @@ template<auto N, typename... Ts>
void
badtype4 ()
{
- Ts...[N] t; // { dg-error "pack index is negative" }
+ Ts...[N] t; // { dg-error "pack index '-1' is negative" }
}
int nonconst () { return 42; }
diff --git a/gcc/testsuite/g++.dg/ext/type_pack_element2.C
b/gcc/testsuite/g++.dg/ext/type_pack_element2.C
index 1bf77534097f..1b076733d97d 100644
--- a/gcc/testsuite/g++.dg/ext/type_pack_element2.C
+++ b/gcc/testsuite/g++.dg/ext/type_pack_element2.C
@@ -2,7 +2,7 @@
int p;
-using type = __type_pack_element<&p, int>; // { dg-error "not an integral
constant" }
+using type = __type_pack_element<&p, int>; // { dg-error "non-integral
type" }
using type = __type_pack_element<1, int>; // { dg-error "out of range" }
using type = __type_pack_element<2, int, char>; // { dg-error "out of range" }
using type = __type_pack_element<-1, int>; // { dg-error "negative" }
diff --git a/gcc/testsuite/g++.dg/ext/type_pack_element4.C
b/gcc/testsuite/g++.dg/ext/type_pack_element4.C
index aa508c79090b..5a391947c7be 100644
--- a/gcc/testsuite/g++.dg/ext/type_pack_element4.C
+++ b/gcc/testsuite/g++.dg/ext/type_pack_element4.C
@@ -3,7 +3,7 @@
template <typename... _Elements> class tuple{};
template <unsigned long __i, typename... _Elements>
-__type_pack_element<__i, _Elements...> &get(tuple<_Elements...> &__t)
noexcept; // { dg-error "index is out of range" }
+__type_pack_element<__i, _Elements...> &get(tuple<_Elements...> &__t)
noexcept; // { dg-error "out of range" }
tuple<int,int> data;
template <unsigned long Level>
unsigned take_impl(unsigned idx) {
diff --git a/libstdc++-v3/testsuite/20_util/tuple/element_access/get_neg.cc
b/libstdc++-v3/testsuite/20_util/tuple/element_access/get_neg.cc
index 48628a98884b..18d47d266ce8 100644
--- a/libstdc++-v3/testsuite/20_util/tuple/element_access/get_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/tuple/element_access/get_neg.cc
@@ -61,4 +61,4 @@ test03()
// { dg-error "tuple index must be in range" "" { target *-*-* } 0 }
// { dg-prune-output "no type named 'type' in .*_Nth_type" }
-// { dg-prune-output "pack index is out of range" }
+// { dg-prune-output "pack index '.' is out of range" }
