[C++ Patch] PR 65775 ("Late-specified return type bypasses return type checks (qualified, function, array)")
Hi, in grokdeclarator the checks on the return type do nothing useful in case of late-specified return type because they happen too early, before splice_late_return_type is called. A straightforward way to solve the problem involves separating the checks themselves to a new check_function_return_type and calling it again only in case splice_late_return_type actually spliced the late return type (in that case, we should also consistently update type_quals). As a side issue, if we want to use good and consistent locations for the error messages (the testcase below checks that too), we need a fall back to input_location for typespec_loc, because otherwise an UNKNOWN_LOCATION is used for the error messages of testcases like lambda-syntax1.C and pr60190.C. Tested x86_64-linux. Thanks, Paolo. / /cp 2017-06-25 Paolo Carlini PR c++/65775 * decl.c (check_function_return_type): New. (grokdeclarator): Use the latter; if declspecs->locations[ds_type_spec] is UNKNOWN_LOCATION fall back to input_location. /testsuite 2017-06-25 Paolo Carlini PR c++/65775 * g++.dg/cpp0x/trailing14.C: New. Index: testsuite/g++.dg/cpp0x/trailing14.C === --- testsuite/g++.dg/cpp0x/trailing14.C (revision 0) +++ testsuite/g++.dg/cpp0x/trailing14.C (working copy) @@ -0,0 +1,15 @@ +// PR c++/65775 +// { dg-do compile { target c++11 } } +// { dg-options "-Wignored-qualifiers" } + +using Qi = int const volatile; +Qi q1(); // { dg-warning "1: type qualifiers ignored" } +auto q2() -> Qi; // { dg-warning "1: type qualifiers ignored" } + +using Fi = int(); +Fi f1(); // { dg-error "1: 'f1' declared as function returning a function" } +auto f2() -> Fi; // { dg-error "1: 'f2' declared as function returning a function" } + +using Ai = int[5]; +Ai a1(); // { dg-error "1: 'a1' declared as function returning an array" } +auto a2() -> Ai; // { dg-error "1: 'a2' declared as function returning an array" } Index: cp/decl.c === --- cp/decl.c (revision 249632) +++ cp/decl.c (working copy) @@ -9789,7 +9789,43 @@ mark_inline_variable (tree decl) } } +/* If TYPE has TYPE_QUALS != TYPE_UNQUALIFIED issue a warning controlled by + -Wignored-qualifiers and clear TYPE_QUALS to avoid cascading diagnostics. + If TYPE is not valid, issue an error message and return error_mark_node, + otherwise return TYPE itself. */ +static tree +check_function_return_type (tree type, int& type_quals, + const char* name, location_t loc) +{ + if (type_quals != TYPE_UNQUALIFIED) +{ + if (SCALAR_TYPE_P (type) || VOID_TYPE_P (type)) + warning_at (loc, OPT_Wignored_qualifiers, "type " + "qualifiers ignored on function return type"); + + /* We now know that the TYPE_QUALS don't apply to the +decl, but to its return type. */ + type_quals = TYPE_UNQUALIFIED; +} + + /* Error about some types functions can't return. */ + + if (TREE_CODE (type) == FUNCTION_TYPE) +{ + error_at (loc, "%qs declared as function returning a function", name); + return error_mark_node; +} + + if (TREE_CODE (type) == ARRAY_TYPE) +{ + error_at (loc, "%qs declared as function returning an array", name); + return error_mark_node; +} + + return type; +} + /* Assign a typedef-given name to a class or enumeration type declared as anonymous at first. This was split out of grokdeclarator because it is also used in libcc1. */ @@ -9993,6 +10029,8 @@ grokdeclarator (const cp_declarator *declarator, declspecs->locations); if (typespec_loc == UNKNOWN_LOCATION) typespec_loc = declspecs->locations[ds_type_spec]; + if (typespec_loc == UNKNOWN_LOCATION) +typespec_loc = input_location; /* Look inside a declarator for the name being declared and get it as a string, for an error message. */ @@ -10828,31 +10866,10 @@ grokdeclarator (const cp_declarator *declarator, /* Declaring a function type. Make sure we have a valid type for the function to return. */ - if (type_quals != TYPE_UNQUALIFIED) - { - if (SCALAR_TYPE_P (type) || VOID_TYPE_P (type)) - { - warning_at (typespec_loc, OPT_Wignored_qualifiers, "type " - "qualifiers ignored on function return type"); - } - /* We now know that the TYPE_QUALS don't apply to the - decl, but to its return type. */ - type_quals = TYPE_UNQUALIFIED; - } + if (check_function_return_type (type, type_quals, name, typespec_loc) + == error_mark_node) + return error_mark_node; - /*
Re: [C++ Patch] PR 65775 ("Late-specified return type bypasses return type checks (qualified, function, array)")
... in fact, simply moving the checks forward, past the splice_late_return_type call, appears to work fine. I'm finishing testing the below. Thanks! Paolo. / /cp 2017-06-25 Paolo Carlini PR c++/65775 * decl.c (grokdeclarator): Move checks on function return type after the splice_late_return_type call; if declspecs->locations[ds_type_spec] is UNKNOWN_LOCATION fall back to input_location. /testsuite 2017-06-25 Paolo Carlini PR c++/65775 * g++.dg/cpp0x/trailing14.C: New. Index: testsuite/g++.dg/cpp0x/trailing14.C === --- testsuite/g++.dg/cpp0x/trailing14.C (revision 0) +++ testsuite/g++.dg/cpp0x/trailing14.C (working copy) @@ -0,0 +1,15 @@ +// PR c++/65775 +// { dg-do compile { target c++11 } } +// { dg-options "-Wignored-qualifiers" } + +using Qi = int const volatile; +Qi q1(); // { dg-warning "1: type qualifiers ignored" } +auto q2() -> Qi; // { dg-warning "1: type qualifiers ignored" } + +using Fi = int(); +Fi f1(); // { dg-error "1: 'f1' declared as function returning a function" } +auto f2() -> Fi; // { dg-error "1: 'f2' declared as function returning a function" } + +using Ai = int[5]; +Ai a1(); // { dg-error "1: 'a1' declared as function returning an array" } +auto a2() -> Ai; // { dg-error "1: 'a2' declared as function returning an array" } Index: cp/decl.c === --- cp/decl.c (revision 249632) +++ cp/decl.c (working copy) @@ -9993,6 +9993,8 @@ grokdeclarator (const cp_declarator *declarator, declspecs->locations); if (typespec_loc == UNKNOWN_LOCATION) typespec_loc = declspecs->locations[ds_type_spec]; + if (typespec_loc == UNKNOWN_LOCATION) +typespec_loc = input_location; /* Look inside a declarator for the name being declared and get it as a string, for an error message. */ @@ -10825,34 +10827,8 @@ grokdeclarator (const cp_declarator *declarator, tree arg_types; int funcdecl_p; - /* Declaring a function type. - Make sure we have a valid type for the function to return. */ + /* Declaring a function type. */ - if (type_quals != TYPE_UNQUALIFIED) - { - if (SCALAR_TYPE_P (type) || VOID_TYPE_P (type)) - { - warning_at (typespec_loc, OPT_Wignored_qualifiers, "type " - "qualifiers ignored on function return type"); - } - /* We now know that the TYPE_QUALS don't apply to the - decl, but to its return type. */ - type_quals = TYPE_UNQUALIFIED; - } - - /* Error about some types functions can't return. */ - - if (TREE_CODE (type) == FUNCTION_TYPE) - { - error ("%qs declared as function returning a function", name); - return error_mark_node; - } - if (TREE_CODE (type) == ARRAY_TYPE) - { - error ("%qs declared as function returning an array", name); - return error_mark_node; - } - input_location = declspecs->locations[ds_type_spec]; abstract_virtuals_error (ACU_RETURN, type); input_location = saved_loc; @@ -10959,8 +10935,36 @@ grokdeclarator (const cp_declarator *declarator, return error_mark_node; if (late_return_type) - late_return_type_p = true; + { + late_return_type_p = true; + type_quals = cp_type_quals (type); + } + if (type_quals != TYPE_UNQUALIFIED) + { + if (SCALAR_TYPE_P (type) || VOID_TYPE_P (type)) + warning_at (typespec_loc, OPT_Wignored_qualifiers, "type " + "qualifiers ignored on function return type"); + /* We now know that the TYPE_QUALS don't apply to the + decl, but to its return type. */ + type_quals = TYPE_UNQUALIFIED; + } + + /* Error about some types functions can't return. */ + + if (TREE_CODE (type) == FUNCTION_TYPE) + { + error_at (typespec_loc, "%qs declared as function returning " + "a function", name); + return error_mark_node; + } + if (TREE_CODE (type) == ARRAY_TYPE) + { + error_at (typespec_loc, "%qs declared as function returning " + "an array", name); + return error_mark_node; + } + if (ctype == NULL_TREE && decl_context == FIELD && funcdecl_p
Re: [C++ Patch] PR 65775 ("Late-specified return type bypasses return type checks (qualified, function, array)")
OK. On Sun, Jun 25, 2017 at 8:18 PM, Paolo Carlini wrote: > ... in fact, simply moving the checks forward, past the > splice_late_return_type call, appears to work fine. I'm finishing testing > the below. > > Thanks! > Paolo. > > /