Tested x86_64-pc-linux-gnu, applying to trunk.
-- 8< --
In r14-1659 I added a missing error for a Concepts TS feature that we were
failing to diagnose, but this PR requests a way to disable that error for
code written thinking it was valid. Which seems reasonable, since it
doesn't require any work beyond that and is a plausible extension by itself.
While looking at this, I also noticed we were still not giving the
diagnostic in a few cases, and fixing that affected a few of our old
concepts testcases.
PR c++/120917
gcc/ChangeLog:
* doc/invoke.texi: Add -Wno-abbreviated-auto-in-template-arg.
gcc/c-family/ChangeLog:
* c.opt: Add -Wno-abbreviated-auto-in-template-arg.
* c.opt.urls: Regenerate.
gcc/cp/ChangeLog:
* parser.cc (cp_parser_simple_type_specifier): Attach
auto in targ in parameter to -Wabbreviated-auto-in-template-arg.
(cp_parser_placeholder_type_specifier): Diagnose constrained auto in
template arg.
gcc/testsuite/ChangeLog:
* g++.dg/concepts/auto7a.C: Add diagnostic.
* g++.dg/concepts/auto7b.C: New test.
* g++.dg/concepts/auto7c.C: New test.
* g++.dg/cpp1y/pr85076.C: Expect 'auto' error.
* g++.dg/concepts/pr67249.C: Likewise.
* g++.dg/cpp1y/lambda-generic-variadic.C: Likewise.
* g++.dg/cpp2a/concepts-pr67210.C: Likewise.
* g++.dg/concepts/pr67249a.C: New test.
* g++.dg/cpp1y/lambda-generic-variadic-a.C: New test.
* g++.dg/cpp2a/concepts-pr67210a.C: New test.
---
gcc/doc/invoke.texi | 18 ++++++++++++++++++
gcc/c-family/c.opt | 4 ++++
gcc/cp/parser.cc | 12 +++++++++---
gcc/testsuite/g++.dg/concepts/auto7a.C | 1 +
gcc/testsuite/g++.dg/concepts/auto7b.C | 10 ++++++++++
gcc/testsuite/g++.dg/concepts/auto7c.C | 12 ++++++++++++
gcc/testsuite/g++.dg/concepts/pr67249.C | 2 +-
gcc/testsuite/g++.dg/concepts/pr67249a.C | 7 +++++++
.../g++.dg/cpp1y/lambda-generic-variadic-a.C | 15 +++++++++++++++
.../g++.dg/cpp1y/lambda-generic-variadic.C | 4 ++--
gcc/testsuite/g++.dg/cpp1y/pr85076.C | 2 +-
gcc/testsuite/g++.dg/cpp2a/concepts-pr67210.C | 2 +-
gcc/testsuite/g++.dg/cpp2a/concepts-pr67210a.C | 11 +++++++++++
gcc/c-family/c.opt.urls | 3 +++
14 files changed, 95 insertions(+), 8 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/concepts/auto7b.C
create mode 100644 gcc/testsuite/g++.dg/concepts/auto7c.C
create mode 100644 gcc/testsuite/g++.dg/concepts/pr67249a.C
create mode 100644 gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic-a.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-pr67210a.C
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 7640e7d8867..74f5ee26042 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -3816,6 +3816,23 @@ Warn when a type with an ABI tag is used in a context
that does not
have that ABI tag. See @ref{C++ Attributes} for more information
about ABI tags.
+@opindex Wabbreviated-auto-in-template-arg
+@opindex Wno-abbreviated-auto-in-template-arg
+@item -Wno-abbreviated-auto-in-template-arg
+Disable the error for an @code{auto} placeholder type used within a
+template argument list to declare a C++20 abbreviated function
+template, e.g.
+
+@smallexample
+void f(S<auto>);
+@end smallexample
+
+This feature was proposed in the Concepts TS, but was not adopted into
+C++20; in the standard, a placeholder in a parameter declaration must
+appear as a decl-specifier. The error can also be reduced to a
+warning by @option{-fpermissive} or
+@option{-Wno-error=abbreviated-auto-in-template-arg}.
+
@opindex Wcomma-subscript
@opindex Wno-comma-subscript
@item -Wcomma-subscript @r{(C++ and Objective-C++ only)}
@@ -6443,6 +6460,7 @@ only by this flag, but it also downgrades some C and C++
diagnostics
that have their own flag:
@gccoptlist{
+-Wabbreviated-auto-in-template-arg @r{(C++ and Objective-C++ only)}
-Wdeclaration-missing-parameter-type @r{(C and Objective-C only)}
-Wimplicit-function-declaration @r{(C and Objective-C only)}
-Wimplicit-int @r{(C and Objective-C only)}
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 8af466d1ed1..6a55e7118d1 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -397,6 +397,10 @@ Wassign-intercept
ObjC ObjC++ Var(warn_assign_intercept) Warning
Warn whenever an Objective-C assignment is being intercepted by the garbage
collector.
+Wabbreviated-auto-in-template-arg
+C++ ObjC++ Warning Var(warn_abbev_auto_targ) Init(1)
+Diagnose a placeholder type in a template argument in a function parameter
type.
+
Wbad-function-cast
C ObjC Var(warn_bad_function_cast) Warning
Warn about casting functions to incompatible types.
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 44a78324c6e..239e6f9a556 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -21021,9 +21021,6 @@ cp_parser_simple_type_specifier (cp_parser* parser,
"only available with "
"%<-std=c++14%> or %<-std=gnu++14%>");
}
- else if (parser->in_template_argument_list_p)
- error_at (token->location,
- "use of %<auto%> in template argument");
else if (!flag_concepts)
pedwarn (token->location, OPT_Wc__20_extensions,
"use of %<auto%> in parameter declaration "
@@ -21033,6 +21030,11 @@ cp_parser_simple_type_specifier (cp_parser* parser,
"use of %<auto%> in parameter declaration "
"only available with "
"%<-std=c++14%> or %<-std=gnu++14%>");
+
+ if (parser->in_template_argument_list_p)
+ permerror_opt (token->location,
+ OPT_Wabbreviated_auto_in_template_arg,
+ "use of %<auto%> in template argument");
}
else
type = make_auto ();
@@ -21479,6 +21481,10 @@ cp_parser_placeholder_type_specifier (cp_parser
*parser, location_t loc,
error_at (loc, "cannot declare a parameter with %<decltype(auto)%>");
return error_mark_node;
}
+ if (parser->in_template_argument_list_p)
+ permerror_opt (placeholder->location,
+ OPT_Wabbreviated_auto_in_template_arg,
+ "use of %<auto%> in template argument");
tree parm = build_constrained_parameter (con, proto, args);
return synthesize_implicit_template_parm (parser, parm);
}
diff --git a/gcc/testsuite/g++.dg/concepts/auto7a.C
b/gcc/testsuite/g++.dg/concepts/auto7a.C
index 88868f45d1c..f36038d2fb4 100644
--- a/gcc/testsuite/g++.dg/concepts/auto7a.C
+++ b/gcc/testsuite/g++.dg/concepts/auto7a.C
@@ -2,6 +2,7 @@
template <class T> struct A { };
void f(A<auto> a) { } // { dg-error "auto. in template argument" }
+// { dg-message "in parameter declaration" "" { target c++17_down } .-1 }
int main()
{
f(A<int>());
diff --git a/gcc/testsuite/g++.dg/concepts/auto7b.C
b/gcc/testsuite/g++.dg/concepts/auto7b.C
new file mode 100644
index 00000000000..874192c0385
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/auto7b.C
@@ -0,0 +1,10 @@
+// PR c++/120917
+// { dg-do compile { target c++14 } }
+// { dg-additional-options "-fconcepts -Wno-abbreviated-auto-in-template-arg" }
+
+template <class T> struct A { };
+void f(A<auto> a) { }
+int main()
+{
+ f(A<int>());
+}
diff --git a/gcc/testsuite/g++.dg/concepts/auto7c.C
b/gcc/testsuite/g++.dg/concepts/auto7c.C
new file mode 100644
index 00000000000..5b16027e2b6
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/auto7c.C
@@ -0,0 +1,12 @@
+// { dg-do compile { target c++17 } }
+// { dg-additional-options -fconcepts }
+
+template <class T>
+concept True = true;
+
+template <class T> struct A { };
+void f(A<True auto> a) { } // { dg-error "use of .auto. in template argument" }
+int main()
+{
+ f(A<int>());
+}
diff --git a/gcc/testsuite/g++.dg/concepts/pr67249.C
b/gcc/testsuite/g++.dg/concepts/pr67249.C
index e0f8d5ade01..e97183d1b21 100644
--- a/gcc/testsuite/g++.dg/concepts/pr67249.C
+++ b/gcc/testsuite/g++.dg/concepts/pr67249.C
@@ -4,4 +4,4 @@
template<class T> concept C1 = true;
template<class A, class B> struct Pair {};
// We used to test "Pair<auto, C1 >".
-void f(Pair<C1 auto, C1 auto>);
+void f(Pair<C1 auto, C1 auto>); // { dg-error "auto" }
diff --git a/gcc/testsuite/g++.dg/concepts/pr67249a.C
b/gcc/testsuite/g++.dg/concepts/pr67249a.C
new file mode 100644
index 00000000000..cb5d90ed361
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/pr67249a.C
@@ -0,0 +1,7 @@
+// { dg-do compile { target c++17 } }
+// { dg-options "-fconcepts -Wno-abbreviated-auto-in-template-arg" }
+
+template<class T> concept C1 = true;
+template<class A, class B> struct Pair {};
+// We used to test "Pair<auto, C1 >".
+void f(Pair<C1 auto, C1 auto>);
diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic-a.C
b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic-a.C
new file mode 100644
index 00000000000..557ecb914ec
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic-a.C
@@ -0,0 +1,15 @@
+// Basic generic lambda test
+// { dg-do run { target c++14 } }
+// { dg-additional-options -Wno-abbreviated-auto-in-template-arg }
+
+template <typename T, typename U> struct pair {};
+template <typename... T> struct tuple {};
+
+int main()
+{
+ auto a = [] (auto, pair<auto,auto> v) { return sizeof (v); };
+ auto b = [] (auto, pair<pair<auto,auto>,auto>... v) { return sizeof... (v);
};
+
+ a(1, pair<int, float>());
+ b(2, pair<pair<short,char>, double>(), pair<pair<float,long>, int>());
+}
diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic.C
b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic.C
index 6d2d250f393..971f58fea0b 100644
--- a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic.C
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic.C
@@ -6,8 +6,8 @@ template <typename... T> struct tuple {};
int main()
{
- auto a = [] (auto, pair<auto,auto> v) { return sizeof (v); };
- auto b = [] (auto, pair<pair<auto,auto>,auto>... v) { return sizeof... (v);
};
+ auto a = [] (auto, pair<auto,auto> v) { return sizeof (v); }; // { dg-error
"auto" }
+ auto b = [] (auto, pair<pair<auto,auto>,auto>... v) { return sizeof... (v);
}; // { dg-error "auto" }
a(1, pair<int, float>());
b(2, pair<pair<short,char>, double>(), pair<pair<float,long>, int>());
diff --git a/gcc/testsuite/g++.dg/cpp1y/pr85076.C
b/gcc/testsuite/g++.dg/cpp1y/pr85076.C
index 6d54dea6c01..b68143b23f9 100644
--- a/gcc/testsuite/g++.dg/cpp1y/pr85076.C
+++ b/gcc/testsuite/g++.dg/cpp1y/pr85076.C
@@ -3,4 +3,4 @@
template<typename> struct A*; // { dg-error "expected unqualified-id before" }
-auto a = [](A<auto>) {}; // { dg-error "is not a template|has incomplete
type" }
+auto a = [](A<auto>) {}; // { dg-error "is not a template|has incomplete
type|auto" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-pr67210.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-pr67210.C
index a31750eb495..baddc1cd465 100644
--- a/gcc/testsuite/g++.dg/cpp2a/concepts-pr67210.C
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-pr67210.C
@@ -7,4 +7,4 @@ concept C = true;
template <class T>
struct A {};
-void f(A<C<int> auto >) {}
+void f(A<C<int> auto >) {} // { dg-error "auto" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-pr67210a.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-pr67210a.C
new file mode 100644
index 00000000000..1d63a844aa4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-pr67210a.C
@@ -0,0 +1,11 @@
+// PR c++/67210
+// { dg-do compile { target c++20 } }
+// { dg-additional-options -Wno-abbreviated-auto-in-template-arg }
+
+template <class T, class U>
+concept C = true;
+
+template <class T>
+struct A {};
+
+void f(A<C<int> auto >) {}
diff --git a/gcc/c-family/c.opt.urls b/gcc/c-family/c.opt.urls
index 65d1221c4ad..401e6e74138 100644
--- a/gcc/c-family/c.opt.urls
+++ b/gcc/c-family/c.opt.urls
@@ -139,6 +139,9 @@ UrlSuffix(gcc/Warning-Options.html#index-Warray-parameter)
Wassign-intercept
UrlSuffix(gcc/Objective-C-and-Objective-C_002b_002b-Dialect-Options.html#index-Wassign-intercept)
+Wabbreviated-auto-in-template-arg
+UrlSuffix(gcc/C_002b_002b-Dialect-Options.html#index-Wabbreviated-auto-in-template-arg)
+
Wbad-function-cast
UrlSuffix(gcc/Warning-Options.html#index-Wbad-function-cast)
base-commit: 0c73f2f1f92c135f50dcc2ab76d5e53236262a4e
--
2.49.0
