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* [gcc r13-2527] c++: diagnostic for template placeholder in parm [PR106793]
@ 2022-09-07 17:37 Jason Merrill
0 siblings, 0 replies; only message in thread
From: Jason Merrill @ 2022-09-07 17:37 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:b9cb441c98f265bff86a1c228932524c5fd37dd3
commit r13-2527-gb9cb441c98f265bff86a1c228932524c5fd37dd3
Author: Jason Merrill <jason@redhat.com>
Date: Fri Sep 2 08:45:02 2022 -0400
c++: diagnostic for template placeholder in parm [PR106793]
Talking about the declarator form doesn't help when fixing that would get
you a different error about placeholders not being valid in a parameter.
This also adds a <> fixit, which isn't enough for most templates, but is a
start.
PR c++/106793
gcc/cp/ChangeLog:
* decl.cc (grokdeclarator): Improve placeholder diagnostics.
* parser.cc (cp_parser_type_id_1): Add fixit.
gcc/testsuite/ChangeLog:
* g++.dg/cpp23/auto-array2.C: Adjust.
* g++.dg/cpp1z/class-deduction113.C: New test.
Diff:
---
gcc/cp/decl.cc | 30 ++++++++++++++++---------
gcc/cp/parser.cc | 7 ++++--
gcc/testsuite/g++.dg/cpp1z/class-deduction113.C | 5 +++++
gcc/testsuite/g++.dg/cpp23/auto-array2.C | 4 ++--
4 files changed, 32 insertions(+), 14 deletions(-)
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 6d20765f40c..4665a29a24d 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -12407,14 +12407,20 @@ grokdeclarator (const cp_declarator *declarator,
if (cxx_dialect >= cxx17 && type && is_auto (type)
&& innermost_code != cdk_function
+ /* Placeholder in parm gets a better error below. */
+ && !(decl_context == PARM || decl_context == CATCHPARM)
&& id_declarator && declarator != id_declarator)
if (tree tmpl = CLASS_PLACEHOLDER_TEMPLATE (type))
- {
- error_at (typespec_loc, "template placeholder type %qT must be followed "
- "by a simple declarator-id", type);
- inform (DECL_SOURCE_LOCATION (tmpl), "%qD declared here", tmpl);
- type = error_mark_node;
- }
+ {
+ auto_diagnostic_group g;
+ gcc_rich_location richloc (typespec_loc);
+ richloc.add_fixit_insert_after ("<>");
+ error_at (&richloc, "missing template argument list after %qE; "
+ "for deduction, template placeholder must be followed "
+ "by a simple declarator-id", tmpl);
+ inform (DECL_SOURCE_LOCATION (tmpl), "%qD declared here", tmpl);
+ type = error_mark_node;
+ }
staticp = 0;
inlinep = decl_spec_seq_has_spec_p (declspecs, ds_inline);
@@ -12892,6 +12898,7 @@ grokdeclarator (const cp_declarator *declarator,
{
if (!funcdecl_p || !dguide_name_p (unqualified_id))
{
+ auto_diagnostic_group g;
error_at (typespec_loc, "deduced class "
"type %qD in function return type",
DECL_NAME (tmpl));
@@ -13837,12 +13844,15 @@ grokdeclarator (const cp_declarator *declarator,
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);
+ gcc_rich_location richloc (typespec_loc);
+ richloc.add_fixit_insert_after ("<>");
+ error_at (&richloc,
+ "missing template argument list after %qE; template "
+ "placeholder not permitted in parameter", c);
if (decl_context == PARM && cxx_dialect >= cxx20)
- inform (typespec_loc, "use %<auto%> for an "
+ inform (typespec_loc, "or use %<auto%> for an "
"abbreviated function template");
+ inform (DECL_SOURCE_LOCATION (c), "%qD declared here", c);
}
else
error_at (typespec_loc,
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 289c2142e45..841ba6ed997 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -24397,8 +24397,11 @@ cp_parser_type_id_1 (cp_parser *parser, cp_parser_flags flags,
location_t loc = type_specifier_seq.locations[ds_type_spec];
if (tree tmpl = CLASS_PLACEHOLDER_TEMPLATE (auto_node))
{
- error_at (loc, "missing template arguments after %qT",
- auto_node);
+ auto_diagnostic_group g;
+ gcc_rich_location richloc (loc);
+ richloc.add_fixit_insert_after ("<>");
+ error_at (&richloc, "missing template arguments after %qE",
+ tmpl);
inform (DECL_SOURCE_LOCATION (tmpl), "%qD declared here",
tmpl);
}
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction113.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction113.C
new file mode 100644
index 00000000000..8f6908e2746
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction113.C
@@ -0,0 +1,5 @@
+// PR c++/106793
+
+template <class T> struct A { A(T); };
+template <class T> void f(A *a); // { dg-error "placeholder.*parameter" "" { target c++17 } }
+// { dg-error "" "" { target c++14_down } .-1 }
diff --git a/gcc/testsuite/g++.dg/cpp23/auto-array2.C b/gcc/testsuite/g++.dg/cpp23/auto-array2.C
index 06431685b30..3fc2eae3cea 100644
--- a/gcc/testsuite/g++.dg/cpp23/auto-array2.C
+++ b/gcc/testsuite/g++.dg/cpp23/auto-array2.C
@@ -5,7 +5,7 @@ template<class T> struct A { A(); };
A<int> a[3];
auto (*p)[3] = &a;
A<int> (*p2)[3] = &a;
-A (*p3)[3] = &a; // { dg-error "template placeholder type" }
+A (*p3)[3] = &a; // { dg-error "template placeholder" }
auto (&r)[3] = a;
A<int> (&r2)[3] = a;
-A (&r3)[3] = a; // { dg-error "template placeholder type" }
+A (&r3)[3] = a; // { dg-error "template placeholder" }
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