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| author | Jason Merrill <jason@redhat.com> | 2020-11-26 05:45:02 -0500 |
|---|---|---|
| committer | Jason Merrill <jason@redhat.com> | 2020-12-02 16:14:53 -0500 |
| commit | 2847d7d28ea79e2f93049fad16f931b6705c9fff (patch) | |
| tree | 098a2060ff83707d5fea5078548813d1094eda7d | |
| parent | d9288bd28e24c755a7216311ee5247e7c88270a6 (diff) | |
| download | gcc-2847d7d28ea79e2f93049fad16f931b6705c9fff.zip gcc-2847d7d28ea79e2f93049fad16f931b6705c9fff.tar.gz gcc-2847d7d28ea79e2f93049fad16f931b6705c9fff.tar.bz2 | |
c++: Give better placeholder diagnostic
We were saying 'auto parameter not permitted' in a place where 'auto' is in
fact permitted in C++20, but a class template placeholder is not.
gcc/cp/ChangeLog:
* decl.c (grokdeclarator): Improve diagnostic for
disallowed CTAD placeholder.
gcc/testsuite/ChangeLog:
* g++.dg/other/pr88187.C: Adjust expected error.
* g++.dg/cpp2a/class-deduction-abbrev1.C: New test.
| -rw-r--r-- | gcc/cp/decl.c | 10 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp2a/class-deduction-abbrev1.C | 13 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/other/pr88187.C | 2 |
3 files changed, 24 insertions, 1 deletions
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c index 1e2bae4..0cf84a0 100644 --- a/gcc/cp/decl.c +++ b/gcc/cp/decl.c @@ -13145,6 +13145,16 @@ grokdeclarator (const cp_declarator *declarator, if (decl_context == PARM && AUTO_IS_DECLTYPE (auto_node)) error_at (typespec_loc, "cannot declare a parameter with %<decltype(auto)%>"); + else if (tree c = CLASS_PLACEHOLDER_TEMPLATE (auto_node)) + { + auto_diagnostic_group g; + error_at (typespec_loc, + "class template placeholder %qE not permitted " + "in this context", c); + if (decl_context == PARM && cxx_dialect >= cxx20) + inform (typespec_loc, "use %<auto%> for an " + "abbreviated function template"); + } else error_at (typespec_loc, "%<auto%> parameter not permitted in this context"); diff --git a/gcc/testsuite/g++.dg/cpp2a/class-deduction-abbrev1.C b/gcc/testsuite/g++.dg/cpp2a/class-deduction-abbrev1.C new file mode 100644 index 0000000..f931009 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/class-deduction-abbrev1.C @@ -0,0 +1,13 @@ + // { dg-do compile { target c++20 } } + +template <class T> struct A { }; +template <class T> concept is_A = requires { A(T()); }; + +void f(auto); // OK +void f(is_A auto); // OK +void f(A); // { dg-error "placeholder" } + +int main() +{ + f(A<int>()); +} diff --git a/gcc/testsuite/g++.dg/other/pr88187.C b/gcc/testsuite/g++.dg/other/pr88187.C index ebdafdd..13466d3 100644 --- a/gcc/testsuite/g++.dg/other/pr88187.C +++ b/gcc/testsuite/g++.dg/other/pr88187.C @@ -4,4 +4,4 @@ template <int> struct A; void f (A ()); // { dg-error "6:variable or field 'f' declared void" "" { target c++14_down } } // { dg-error "missing template arguments before '\\(' token" "" { target c++14_down } .-1 } - // { dg-error "'auto' parameter not permitted in this context" "" { target c++17 } .-2 } + // { dg-error "placeholder .A. not permitted in this context" "" { target c++17 } .-2 } |