OK, on the right patch this time I hope.
Looks like you still need either FSF copyright assignment or DCO
certification per https://gcc.gnu.org/contribute.html#legal
On 5/15/24 13:27, Seyed Sajad Kahani wrote:
This patch resolves PR114915 by replacing the logic that fills in the
missing levels in do_auto_deduction in cp/pt.cc.
I miss the text in your original patch that explained the problem more.
The new approach now trims targs if the depth of targs is deeper than desired
(this will only happen in specific contexts), and still fills targs with empty
layers if it has fewer depths than expected.
PR c++/114915
This line needs to start with a tab.
gcc/cp/ChangeLog:
* pt.cc (do_auto_deduction): Handle excess outer template
arguments during constrained auto satisfaction.
This one, too. These issues are flagged by git gcc-verify, and are
easier to avoid with git gcc-commit-mklog.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/concepts-placeholder14.C: New test.
* g++.dg/cpp2a/concepts-placeholder15.C: New test.
This test still needs a variable template partial specialization.
A few coding style nits below.
* g++.dg/cpp2a/concepts-placeholder16.C: New test.
---
gcc/cp/pt.cc | 20 ++++++++---
.../g++.dg/cpp2a/concepts-placeholder14.C | 19 +++++++++++
.../g++.dg/cpp2a/concepts-placeholder15.C | 15 +++++++++
.../g++.dg/cpp2a/concepts-placeholder16.C | 33 +++++++++++++++++++
4 files changed, 83 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-placeholder14.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-placeholder15.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-placeholder16.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 32640f8e9..ecfda67aa 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -31253,6 +31253,19 @@ do_auto_deduction (tree type, tree init, tree
auto_node,
full_targs = add_outermost_template_args (tmpl, full_targs);
full_targs = add_to_template_args (full_targs, targs);
+ int want = TEMPLATE_TYPE_ORIG_LEVEL (auto_node);
+ int have = TMPL_ARGS_DEPTH (full_targs);
+
+ if (want < have)
+ {
+ // if a constrained auto is declared in an explicit specialization
We generally use C-style /* */ comments, that start with a capital
letter and end with a period.
+ gcc_assert (context == adc_variable_type || context == adc_return_type
+ || context == adc_decomp_type);
The || should line up with the 'c' on the previous line.
+ tree trimmed_full_args = get_innermost_template_args
+ (full_targs, want);
We try to avoid having arguments to the left of the function name; here
I'd start the new line with the = instead.
+ full_targs = trimmed_full_args;
+ }
+
Unnecessary tab on this line.
/* HACK: Compensate for callers not always communicating all levels of
outer template arguments by filling in the outermost missing levels
with dummy levels before checking satisfaction. We'll still crash
@@ -31260,11 +31273,10 @@ do_auto_deduction (tree type, tree init, tree
auto_node,
these missing levels, but this hack otherwise allows us to handle a
large subset of possible constraints (including all non-dependent
constraints). */
- if (int missing_levels = (TEMPLATE_TYPE_ORIG_LEVEL (auto_node)
- - TMPL_ARGS_DEPTH (full_targs)))
+ if (want > have)
{
- tree dummy_levels = make_tree_vec (missing_levels);
- for (int i = 0; i < missing_levels; ++i)
+ tree dummy_levels = make_tree_vec (want - have);
+ for (int i = 0; i < want - have; ++i)
TREE_VEC_ELT (dummy_levels, i) = make_tree_vec (0);
full_targs = add_to_template_args (dummy_levels, full_targs);
}
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder14.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder14.C
new file mode 100644
index 000000000..fcdbd7608
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder14.C
@@ -0,0 +1,19 @@
+// PR c++/114915
+// { dg-do compile { target c++20 } }
+
+template<typename T>
+concept C = __is_same(T, int);
+
+template<typename T>
+void f() {
+}
+
+template<>
+void f<int>() {
+ C auto x = 1;
+}
+
+int main() {
+ f<int>();
+ return 0;
+}
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder15.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder15.C
new file mode 100644
index 000000000..b4f73f407
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder15.C
@@ -0,0 +1,15 @@
+// PR c++/114915
+// { dg-do compile { target c++20 } }
+
+template<typename T, typename U>
+concept C = __is_same(T, U);
+
+template<typename T>
+int x = 0;
+
+template<>
+C<double> auto x<double> = 1.0;
+
+int main() {
+ return 0;
+}
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder16.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder16.C
new file mode 100644
index 000000000..f808ef1b6
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder16.C
@@ -0,0 +1,33 @@
+// PR c++/114915
+// { dg-do compile { target c++20 } }
+
+template<typename T, typename U>
+concept C = __is_same(T, U);
+
+template<typename T>
+struct A
+{
+ template<typename U>
+ void f() {
+ }
+};
+
+template<>
+template<>
+void A<int>::f<int>() {
+ C<int> auto x = 1;
+}
+
+template<>
+template<typename U>
+void A<bool>::f() {
+ C<int> auto x = 1;
+}
+
+int main() {
+ A<bool> a;
+ a.f<char>();
+ A<int> b;
+ b.f<int>();
+ return 0;
+}
