Hi!
https://eel.is/c++draft/stmt.ranged#2
says that in for-range-declaration only type-specifier or constexpr
can appear. As the following testcases show, we've emitted some
diagnostics in most cases, but not for static/thread_local (the patch
handles __thread too) and register in the non-sb case.
For extern there was an error that it is both extern and has an
initializer (again, non-sb only, sb errors on extern).
The following patch diagnoses those cases with pedwarn.
I've used for-range-declaration in the diagnostics wording (there was
already a case of that for the typedef), so that in the future
we don't need to differentiate it between range for and expansion
statements.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2025-07-05 Jakub Jelinek <ja...@redhat.com>
PR c++/84009
* parser.cc (cp_parser_decomposition_declaration): Pedwarn
on thread_local, __thread or static in decl_specifiers for
for-range-declaration.
(cp_parser_init_declarator): Likewise, and also for extern
or register.
* g++.dg/cpp0x/range-for40.C: New test.
* g++.dg/cpp0x/range-for41.C: New test.
* g++.dg/cpp0x/range-for42.C: New test.
* g++.dg/cpp0x/range-for43.C: New test.
--- gcc/cp/parser.cc.jj 2025-07-04 19:49:14.702864248 +0200
+++ gcc/cp/parser.cc 2025-07-04 21:29:46.568232075 +0200
@@ -16919,6 +16919,15 @@ cp_parser_decomposition_declaration (cp_
/* Ensure DECL_VALUE_EXPR is created for all the decls but
the underlying DECL. */
cp_finish_decomp (decl, &decomp);
+ if (decl_spec_seq_has_spec_p (decl_specifiers, ds_thread))
+ pedwarn (decl_specifiers->locations[ds_thread],
+ OPT_Wpedantic, "for-range-declaration cannot be %qs",
+ decl_specifiers->gnu_thread_keyword_p
+ ? "__thread" : "thread_local");
+ else if (decl_specifiers->storage_class == sc_static)
+ pedwarn (decl_specifiers->locations[ds_storage_class],
+ OPT_Wpedantic, "for-range-declaration cannot be %qs",
+ "static");
}
if (pushed_scope)
@@ -24162,7 +24171,26 @@ cp_parser_init_declarator (cp_parser* pa
&& token->type != CPP_SEMICOLON)
{
if (maybe_range_for_decl && *maybe_range_for_decl != error_mark_node)
- range_for_decl_p = true;
+ {
+ range_for_decl_p = true;
+ if (decl_spec_seq_has_spec_p (decl_specifiers, ds_thread))
+ pedwarn (decl_specifiers->locations[ds_thread],
+ OPT_Wpedantic, "for-range-declaration cannot be %qs",
+ decl_specifiers->gnu_thread_keyword_p
+ ? "__thread" : "thread_local");
+ else if (decl_specifiers->storage_class == sc_static)
+ pedwarn (decl_specifiers->locations[ds_storage_class],
+ OPT_Wpedantic, "for-range-declaration cannot be %qs",
+ "static");
+ else if (decl_specifiers->storage_class == sc_extern)
+ pedwarn (decl_specifiers->locations[ds_storage_class],
+ OPT_Wpedantic, "for-range-declaration cannot be %qs",
+ "extern");
+ else if (decl_specifiers->storage_class == sc_register)
+ pedwarn (decl_specifiers->locations[ds_storage_class],
+ OPT_Wpedantic, "for-range-declaration cannot be %qs",
+ "register");
+ }
else
{
if (!maybe_range_for_decl)
--- gcc/testsuite/g++.dg/cpp0x/range-for40.C.jj 2025-07-04 21:03:00.951729318
+0200
+++ gcc/testsuite/g++.dg/cpp0x/range-for40.C 2025-07-04 21:11:29.426240713
+0200
@@ -0,0 +1,41 @@
+// PR c++/84009
+// { dg-do compile { target c++11 } }
+
+int z[64];
+
+void
+foo ()
+{
+ for (static auto a : z) // { dg-error "for-range-declaration
cannot be 'static'" }
+ ;
+ for (thread_local auto a : z) // { dg-error
"for-range-declaration cannot be 'thread_local'" }
+ ;
+ for (__thread auto a : z) // { dg-error "for-range-declaration
cannot be '__thread'" }
+ ; // { dg-error "function-scope 'a'
implicitly auto and declared '__thread'" "" { target *-*-* } .-1 }
+ for (register auto a : z) // { dg-error "for-range-declaration
cannot be 'register'" }
+ ; // { dg-error "does not allow
'register' storage class specifier" "" { target c++17 } .-1 }
+ for (extern auto a : z) // { dg-error "for-range-declaration
cannot be 'extern'" }
+ ; // { dg-error "'a' has both 'extern'
and initializer" "" { target *-*-* } .-1 }
+ for (mutable auto a : z) // { dg-error "non-member 'a' cannot be
declared 'mutable'" }
+ ;
+ for (virtual auto a : z) // { dg-error "'virtual' outside class
declaration" }
+ ;
+ for (explicit auto a : z) // { dg-error "'explicit' outside class
declaration" }
+ ;
+ for (friend auto a : z) // { dg-error "'friend' used outside of
class" }
+ ;
+ for (typedef auto a : z) // { dg-error "typedef declared 'auto'"
}
+ ; // { dg-error "typedef 'a' is
initialized \\\(use 'decltype' instead\\\)" "" { target *-*-* } .-1 }
+#if __cplusplus >= 202002L
+ for (consteval auto a : z) // { dg-error "a variable cannot be
declared 'consteval'" "" { target c++20 } }
+ ;
+ for (constinit auto a : z) // { dg-error "'constinit' can only be
applied to a variable with static or thread storage duration" "" { target c++20
} }
+ ;
+#endif
+ for (inline auto a : z) // { dg-error "'inline' specifier
invalid for variable 'a' declared at block scope" }
+ ;
+ for (struct S { int a; } a : z) // { dg-error "types may not be defined
in a for-range-declaration" }
+ ; // { dg-error "conversion from 'int' to
non-scalar type 'foo\\\(\\\)::S' requested" "" { target *-*-* } .-1 }
+ for (enum E { E0 } a : z) // { dg-error "types may not be defined
in a for-range-declaration" }
+ ; // { dg-error "invalid conversion from
'int' to 'foo\\\(\\\)::E'" "" { target *-*-* } .-1 }
+}
--- gcc/testsuite/g++.dg/cpp0x/range-for41.C.jj 2025-07-04 21:12:17.765623538
+0200
+++ gcc/testsuite/g++.dg/cpp0x/range-for41.C 2025-07-04 21:17:07.796920537
+0200
@@ -0,0 +1,42 @@
+// PR c++/84009
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+int z[64];
+
+void
+foo ()
+{
+ for (static auto a : z)
+ ;
+ for (thread_local auto a : z)
+ ;
+ for (__thread auto a : z) // { dg-warning "function-scope 'a'
implicitly auto and declared '__thread'" }
+ ;
+ for (register auto a : z) // { dg-warning "does not allow
'register' storage class specifier" "" { target c++17 } }
+ ;
+ for (extern auto a : z)
+ ; // { dg-error "'a' has both 'extern'
and initializer" "" { target *-*-* } .-1 }
+ for (mutable auto a : z) // { dg-error "non-member 'a' cannot be
declared 'mutable'" }
+ ;
+ for (virtual auto a : z) // { dg-error "'virtual' outside class
declaration" }
+ ;
+ for (explicit auto a : z) // { dg-error "'explicit' outside class
declaration" }
+ ;
+ for (friend auto a : z) // { dg-error "'friend' used outside of
class" }
+ ;
+ for (typedef auto a : z) // { dg-error "typedef declared 'auto'"
}
+ ; // { dg-error "typedef 'a' is
initialized \\\(use 'decltype' instead\\\)" "" { target *-*-* } .-1 }
+#if __cplusplus >= 202002L
+ for (consteval auto a : z) // { dg-error "a variable cannot be
declared 'consteval'" "" { target c++20 } }
+ ;
+ for (constinit auto a : z) // { dg-error "'constinit' can only be
applied to a variable with static or thread storage duration" "" { target c++20
} }
+ ;
+#endif
+ for (inline auto a : z) // { dg-error "'inline' specifier
invalid for variable 'a' declared at block scope" }
+ ;
+ for (struct S { int a; } a : z) // { dg-error "types may not be defined
in a for-range-declaration" }
+ ; // { dg-error "conversion from 'int' to
non-scalar type 'foo\\\(\\\)::S' requested" "" { target *-*-* } .-1 }
+ for (enum E { E0 } a : z) // { dg-error "types may not be defined
in a for-range-declaration" }
+ ; // { dg-error "invalid conversion from
'int' to 'foo\\\(\\\)::E'" "" { target *-*-* } .-1 }
+}
--- gcc/testsuite/g++.dg/cpp0x/range-for42.C.jj 2025-07-04 21:18:01.921229498
+0200
+++ gcc/testsuite/g++.dg/cpp0x/range-for42.C 2025-07-04 21:56:40.358626480
+0200
@@ -0,0 +1,41 @@
+// PR c++/84009
+// { dg-do compile { target c++11 } }
+
+struct S { int y; } z[64];
+
+void
+foo ()
+{
+ for (static auto [ a ] : z) // { dg-error "for-range-declaration
cannot be 'static'" }
+ ; // { dg-error "structured binding
declaration can be 'static' only in" "" { target c++17_down } .-1 }
+ // { dg-error "structured bindings only
available with" "" { target c++14_down } .-2 }
+ for (thread_local auto [ a ] : z) // { dg-error "for-range-declaration
cannot be 'thread_local'" }
+ ; // { dg-error "structured binding
declaration can be 'thread_local' only in" "" { target c++17_down } .-1 }
+ // { dg-error "structured bindings only
available with" "" { target c++14_down } .-2 }
+ for (__thread auto [ a ] : z) // { dg-error
"for-range-declaration cannot be '__thread'" }
+ ; // { dg-error "function-scope
'structured binding' implicitly auto and declared '__thread'" "" { target *-*-*
} .-1 }
+ // { dg-error "structured binding
declaration can be '__thread' only in" "" { target c++17_down } .-2 }
+ // { dg-error "structured bindings only
available with" "" { target c++14_down } .-3 }
+ for (register auto [ a ] : z) // { dg-error "structured
binding declaration cannot be 'register'" }
+ ; // { dg-error "structured bindings only
available with" "" { target c++14_down } .-1 }
+ for (extern auto [ a ] : z) // { dg-error "structured binding
declaration cannot be 'extern'" }
+ ; // { dg-error "structured bindings only
available with" "" { target c++14_down } .-1 }
+ for (mutable auto [ a ] : z) // { dg-error "structured binding
declaration cannot be 'mutable'" }
+ ; // { dg-error "structured bindings only
available with" "" { target c++14_down } .-1 }
+ for (virtual auto [ a ] : z) // { dg-error "'virtual' outside class
declaration" }
+ ; // { dg-error "structured bindings only
available with" "" { target c++14_down } .-1 }
+ for (explicit auto [ a ] : z) // { dg-error "'explicit'
outside class declaration" }
+ ; // { dg-error "structured bindings only
available with" "" { target c++14_down } .-1 }
+ for (friend auto [ a ] : z) // { dg-error "'friend' used outside of
class" }
+ ; // { dg-error "structured bindings only
available with" "" { target c++14_down } .-1 }
+ for (typedef auto [ a ] : z) // { dg-error "structured binding
declaration cannot be 'typedef'" }
+ ; // { dg-error "structured bindings only
available with" "" { target c++14_down } .-1 }
+#if __cplusplus >= 202002L
+ for (consteval auto [ a ] : z) // { dg-error "structured binding
declaration cannot be 'consteval'" "" { target c++20 } }
+ ;
+ for (constinit auto [ a ] : z) // { dg-error "'constinit' can only be
applied to a variable with static or thread storage duration" "" { target c++20
} }
+ ;
+#endif
+ for (inline auto [ a ] : z) // { dg-error "structured binding
declaration cannot be 'inline'" }
+ ; // { dg-error "structured bindings only
available with" "" { target c++14_down } .-1 }
+}
--- gcc/testsuite/g++.dg/cpp0x/range-for43.C.jj 2025-07-04 21:56:56.615418951
+0200
+++ gcc/testsuite/g++.dg/cpp0x/range-for43.C 2025-07-04 22:00:25.885747537
+0200
@@ -0,0 +1,39 @@
+// PR c++/84009
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+struct S { int y; } z[64];
+
+void
+foo ()
+{
+ for (static auto [ a ] : z) // { dg-warning "structured binding
declaration can be 'static' only in" "" { target c++17_down } }
+ ; // { dg-warning "structured bindings
only available with" "" { target c++14_down } .-1 }
+ for (thread_local auto [ a ] : z) // { dg-warning "structured binding
declaration can be 'thread_local' only in" "" { target c++17_down } }
+ ; // { dg-warning "structured bindings
only available with" "" { target c++14_down } .-1 }
+ for (__thread auto [ a ] : z) // { dg-warning "function-scope
'structured binding' implicitly auto and declared '__thread'" }
+ ; // { dg-warning "structured binding
declaration can be '__thread' only in" "" { target c++17_down } .-1 }
+ // { dg-warning "structured bindings
only available with" "" { target c++14_down } .-2 }
+ for (register auto [ a ] : z) // { dg-error "structured
binding declaration cannot be 'register'" }
+ ; // { dg-warning "structured bindings
only available with" "" { target c++14_down } .-1 }
+ for (extern auto [ a ] : z) // { dg-error "structured binding
declaration cannot be 'extern'" }
+ ; // { dg-warning "structured bindings
only available with" "" { target c++14_down } .-1 }
+ for (mutable auto [ a ] : z) // { dg-error "structured binding
declaration cannot be 'mutable'" }
+ ; // { dg-warning "structured bindings
only available with" "" { target c++14_down } .-1 }
+ for (virtual auto [ a ] : z) // { dg-error "'virtual' outside class
declaration" }
+ ; // { dg-warning "structured bindings
only available with" "" { target c++14_down } .-1 }
+ for (explicit auto [ a ] : z) // { dg-error "'explicit'
outside class declaration" }
+ ; // { dg-warning "structured bindings
only available with" "" { target c++14_down } .-1 }
+ for (friend auto [ a ] : z) // { dg-error "'friend' used outside of
class" }
+ ; // { dg-warning "structured bindings
only available with" "" { target c++14_down } .-1 }
+ for (typedef auto [ a ] : z) // { dg-error "structured binding
declaration cannot be 'typedef'" }
+ ; // { dg-warning "structured bindings
only available with" "" { target c++14_down } .-1 }
+#if __cplusplus >= 202002L
+ for (consteval auto [ a ] : z) // { dg-error "structured binding
declaration cannot be 'consteval'" "" { target c++20 } }
+ ;
+ for (constinit auto [ a ] : z) // { dg-error "'constinit' can only be
applied to a variable with static or thread storage duration" "" { target c++20
} }
+ ;
+#endif
+ for (inline auto [ a ] : z) // { dg-error "structured binding
declaration cannot be 'inline'" }
+ ; // { dg-warning "structured bindings
only available with" "" { target c++14_down } .-1 }
+}
Jakub
