| Message ID | 20240830194018.889736-1-polacek@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: fn redecl in fn scope wrongly accepted [PR116239] | expand |
On 8/30/24 3:40 PM, Marek Polacek wrote: > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? > > -- >8 -- > Redeclaration such as > > void f(void); > consteval void f(void); > > is invalid. In a namespace scope, we detect the collision in > validate_constexpr_redeclaration, but not when one declaration is > at block scope. > > When we have > > void f(void); > void g() { consteval void f(void); } > > we call pushdecl on the second f and call push_local_extern_decl_alias. > It finds the namespace-scope f: > > for (ovl_iterator iter (binding); iter; ++iter) > if (decls_match (decl, *iter, /*record_versions*/false)) > { > alias = *iter; > break; > } > > but decls_match says they match so we just set DECL_LOCAL_DECL_ALIAS > (and do not call another pushdecl leading to duplicate_decls which > would detect mismatching return types, for example). I don't think > we want to change decls_match, so a simple fix is to detect the > problem in push_local_extern_decl_alias. > > PR c++/116239 > > gcc/cp/ChangeLog: > > * cp-tree.h (validate_constexpr_redeclaration): Declare. > * decl.cc (validate_constexpr_redeclaration): No longer static. > * name-lookup.cc (push_local_extern_decl_alias): Call > validate_constexpr_redeclaration. > > gcc/testsuite/ChangeLog: > > * g++.dg/diagnostic/redeclaration-6.C: New test. > --- > gcc/cp/cp-tree.h | 1 + > gcc/cp/decl.cc | 2 +- > gcc/cp/name-lookup.cc | 3 ++ > .../g++.dg/diagnostic/redeclaration-6.C | 34 +++++++++++++++++++ > 4 files changed, 39 insertions(+), 1 deletion(-) > create mode 100644 gcc/testsuite/g++.dg/diagnostic/redeclaration-6.C > > diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h > index 2eeb5e3e8b1..1a763b683de 100644 > --- a/gcc/cp/cp-tree.h > +++ b/gcc/cp/cp-tree.h > @@ -6992,6 +6992,7 @@ extern bool member_like_constrained_friend_p (tree); > extern bool fns_correspond (tree, tree); > extern int decls_match (tree, tree, bool = true); > extern bool maybe_version_functions (tree, tree, bool); > +extern bool validate_constexpr_redeclaration (tree, tree); > extern bool merge_default_template_args (tree, tree, bool); > extern tree duplicate_decls (tree, tree, > bool hiding = false, > diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc > index 6458e96bded..4ad68d609d7 100644 > --- a/gcc/cp/decl.cc > +++ b/gcc/cp/decl.cc > @@ -1412,7 +1412,7 @@ check_redeclaration_exception_specification (tree new_decl, > /* Return true if OLD_DECL and NEW_DECL agree on constexprness. > Otherwise issue diagnostics. */ > > -static bool > +bool > validate_constexpr_redeclaration (tree old_decl, tree new_decl) > { > old_decl = STRIP_TEMPLATE (old_decl); > diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc > index 70ad4cbf3b5..6777d97ac2e 100644 > --- a/gcc/cp/name-lookup.cc > +++ b/gcc/cp/name-lookup.cc > @@ -3708,6 +3708,9 @@ push_local_extern_decl_alias (tree decl) > } > } > > + if (!validate_constexpr_redeclaration (alias, decl)) > + return; > + > retrofit_lang_decl (decl); > DECL_LOCAL_DECL_ALIAS (decl) = alias; > } I don't think we need this in the case that we built a new alias and pushed it; in that case alias is built from decl, and should certainly match already. So let's put this call before we decide to build a new alias, either in the loop or just after it. Jason
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index 2eeb5e3e8b1..1a763b683de 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -6992,6 +6992,7 @@ extern bool member_like_constrained_friend_p (tree); extern bool fns_correspond (tree, tree); extern int decls_match (tree, tree, bool = true); extern bool maybe_version_functions (tree, tree, bool); +extern bool validate_constexpr_redeclaration (tree, tree); extern bool merge_default_template_args (tree, tree, bool); extern tree duplicate_decls (tree, tree, bool hiding = false, diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc index 6458e96bded..4ad68d609d7 100644 --- a/gcc/cp/decl.cc +++ b/gcc/cp/decl.cc @@ -1412,7 +1412,7 @@ check_redeclaration_exception_specification (tree new_decl, /* Return true if OLD_DECL and NEW_DECL agree on constexprness. Otherwise issue diagnostics. */ -static bool +bool validate_constexpr_redeclaration (tree old_decl, tree new_decl) { old_decl = STRIP_TEMPLATE (old_decl); diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc index 70ad4cbf3b5..6777d97ac2e 100644 --- a/gcc/cp/name-lookup.cc +++ b/gcc/cp/name-lookup.cc @@ -3708,6 +3708,9 @@ push_local_extern_decl_alias (tree decl) } } + if (!validate_constexpr_redeclaration (alias, decl)) + return; + retrofit_lang_decl (decl); DECL_LOCAL_DECL_ALIAS (decl) = alias; } diff --git a/gcc/testsuite/g++.dg/diagnostic/redeclaration-6.C b/gcc/testsuite/g++.dg/diagnostic/redeclaration-6.C new file mode 100644 index 00000000000..ed8d4af7792 --- /dev/null +++ b/gcc/testsuite/g++.dg/diagnostic/redeclaration-6.C @@ -0,0 +1,34 @@ +// PR c++/116239 +// { dg-do compile { target c++20 } } + +consteval void f1(); +void f2(); +constexpr void f3(); +void f4(); +consteval void f5(); +constexpr void f6(); + +void +g () +{ + void f1(); // { dg-error "differs in .consteval." } + consteval void f2(); // { dg-error "differs in .consteval." } + + void f3(); // { dg-error "differs in .constexpr." } + constexpr void f4(); // { dg-error "differs in .constexpr." } + + consteval void f5(); + constexpr void f6(); + + void f7(); + consteval void f7(); // { dg-error "differs in .consteval." } + + consteval void f8(); + void f8(); // { dg-error "differs in .consteval." } + + void f9(); + constexpr void f9(); // { dg-error "differs in .constexpr." } + + constexpr void f10(); + void f10(); // { dg-error "differs in .constexpr." } +}
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? -- >8 -- Redeclaration such as void f(void); consteval void f(void); is invalid. In a namespace scope, we detect the collision in validate_constexpr_redeclaration, but not when one declaration is at block scope. When we have void f(void); void g() { consteval void f(void); } we call pushdecl on the second f and call push_local_extern_decl_alias. It finds the namespace-scope f: for (ovl_iterator iter (binding); iter; ++iter) if (decls_match (decl, *iter, /*record_versions*/false)) { alias = *iter; break; } but decls_match says they match so we just set DECL_LOCAL_DECL_ALIAS (and do not call another pushdecl leading to duplicate_decls which would detect mismatching return types, for example). I don't think we want to change decls_match, so a simple fix is to detect the problem in push_local_extern_decl_alias. PR c++/116239 gcc/cp/ChangeLog: * cp-tree.h (validate_constexpr_redeclaration): Declare. * decl.cc (validate_constexpr_redeclaration): No longer static. * name-lookup.cc (push_local_extern_decl_alias): Call validate_constexpr_redeclaration. gcc/testsuite/ChangeLog: * g++.dg/diagnostic/redeclaration-6.C: New test. --- gcc/cp/cp-tree.h | 1 + gcc/cp/decl.cc | 2 +- gcc/cp/name-lookup.cc | 3 ++ .../g++.dg/diagnostic/redeclaration-6.C | 34 +++++++++++++++++++ 4 files changed, 39 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/diagnostic/redeclaration-6.C base-commit: b222122d4e93de2238041a01b1886c7dfd9944da