* [pushed] c++: Push parms when late parsing default args
@ 2020-12-03 3:17 Jason Merrill
2020-12-03 17:29 ` Rainer Orth
0 siblings, 1 reply; 2+ messages in thread
From: Jason Merrill @ 2020-12-03 3:17 UTC (permalink / raw)
To: gcc-patches
In this testcase we weren't catching the error in A::f because the parameter
'I' wasn't in scope, so the default argument for 'b' found the global
typedef I. Fixed by pushing the parms before parsing. This is a bit
complicated because pushdecl clears DECL_CHAIN; do_push_parm_decls deals
with this by nreversing first, but that doesn't work here because we only
want to push them one at a time; if we pushed all of them before parsing,
we'd wrongly reject A::g.
Tested x86_64-pc-linux-gnu, applying to trunk.
gcc/cp/ChangeLog:
* parser.c (cp_parser_primary_expression): Distinguish
parms from vars in error.
(cp_parser_late_parsing_default_args): Pushdecl parms
as we go.
gcc/testsuite/ChangeLog:
* g++.dg/parse/defarg17.C: New test.
---
gcc/cp/parser.c | 32 ++++++++++++++++++++++-----
gcc/testsuite/g++.dg/parse/defarg17.C | 11 +++++++++
2 files changed, 37 insertions(+), 6 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/parse/defarg17.C
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index a8e86cf250d..ef4d73d6161 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -5814,8 +5814,11 @@ cp_parser_primary_expression (cp_parser *parser,
if ((parser->local_variables_forbidden_p & LOCAL_VARS_FORBIDDEN)
&& local_variable_p (decl))
{
- error_at (id_expression.get_location (),
- "local variable %qD may not appear in this context",
+ const char *msg
+ = (TREE_CODE (decl) == PARM_DECL
+ ? _("parameter %qD may not appear in this context")
+ : _("local variable %qD may not appear in this context"));
+ error_at (id_expression.get_location (), msg,
decl.get_value ());
return error_mark_node;
}
@@ -30551,7 +30554,6 @@ static void
cp_parser_late_parsing_default_args (cp_parser *parser, tree fn)
{
unsigned char saved_local_variables_forbidden_p;
- tree parm, parmdecl;
/* While we're parsing the default args, we might (due to the
statement expression extension) encounter more classes. We want
@@ -30568,11 +30570,18 @@ cp_parser_late_parsing_default_args (cp_parser *parser, tree fn)
begin_scope (sk_function_parms, fn);
- for (parm = TYPE_ARG_TYPES (TREE_TYPE (fn)),
- parmdecl = DECL_ARGUMENTS (fn);
+ /* Gather the PARM_DECLs into a vec so we can keep track of them when
+ pushdecl clears DECL_CHAIN. */
+ releasing_vec parms;
+ for (tree parmdecl = DECL_ARGUMENTS (fn); parmdecl;
+ parmdecl = DECL_CHAIN (parmdecl))
+ vec_safe_push (parms, parmdecl);
+
+ tree parm = TYPE_ARG_TYPES (TREE_TYPE (fn));
+ for (int i = 0;
parm && parm != void_list_node;
parm = TREE_CHAIN (parm),
- parmdecl = DECL_CHAIN (parmdecl))
+ ++i)
{
tree default_arg = TREE_PURPOSE (parm);
tree parsed_arg;
@@ -30580,6 +30589,9 @@ cp_parser_late_parsing_default_args (cp_parser *parser, tree fn)
tree copy;
unsigned ix;
+ tree parmdecl = parms[i];
+ pushdecl (parmdecl);
+
if (!default_arg)
continue;
@@ -30602,6 +30614,14 @@ cp_parser_late_parsing_default_args (cp_parser *parser, tree fn)
pop_bindings_and_leave_scope ();
+ /* Restore DECL_CHAINs after clobbering by pushdecl. */
+ parm = NULL_TREE;
+ for (int i = parms->length () - 1; i >= 0; --i)
+ {
+ DECL_CHAIN (parms[i]) = parm;
+ parm = parms[i];
+ }
+
pop_defarg_context ();
/* Make sure no default arg is missing. */
diff --git a/gcc/testsuite/g++.dg/parse/defarg17.C b/gcc/testsuite/g++.dg/parse/defarg17.C
new file mode 100644
index 00000000000..c39a819c723
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/defarg17.C
@@ -0,0 +1,11 @@
+typedef int I;
+
+int f(float I = 0.0, int b = I(2)); // { dg-error "parameter" }
+int g(int b = I(2), float I = 0.0);
+
+struct A
+{
+ int f(float I = 0.0, int b = I(2)); // { dg-error "parameter" }
+ int g(int b = I(2), float I = 0.0);
+};
+
base-commit: 54f97a226a0d8b315aa1a0129df957a8bb3fdf65
--
2.27.0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [pushed] c++: Push parms when late parsing default args
2020-12-03 3:17 [pushed] c++: Push parms when late parsing default args Jason Merrill
@ 2020-12-03 17:29 ` Rainer Orth
0 siblings, 0 replies; 2+ messages in thread
From: Rainer Orth @ 2020-12-03 17:29 UTC (permalink / raw)
To: Jason Merrill via Gcc-patches
Hi Jason,
> In this testcase we weren't catching the error in A::f because the parameter
> 'I' wasn't in scope, so the default argument for 'b' found the global
> typedef I. Fixed by pushing the parms before parsing. This is a bit
> complicated because pushdecl clears DECL_CHAIN; do_push_parm_decls deals
> with this by nreversing first, but that doesn't work here because we only
> want to push them one at a time; if we pushed all of them before parsing,
> we'd wrongly reject A::g.
>
> Tested x86_64-pc-linux-gnu, applying to trunk.
>
> gcc/cp/ChangeLog:
>
> * parser.c (cp_parser_primary_expression): Distinguish
> parms from vars in error.
> (cp_parser_late_parsing_default_args): Pushdecl parms
> as we go.
this patch broke i386-pc-solaris2.11 and sparc-sun-solaris2.11 bootstrap
with gcc 8.1.0 in stage 1:
/vol/gcc/src/hg/master/local/gcc/cp/parser.c: In function 'void cp_parser_late_parsing_default_args(cp_parser*, tree)':
/vol/gcc/src/hg/master/local/gcc/cp/parser.c:30618:28: error: ambiguous overload for 'operator[]' (operand types are 'releasing_vec' and 'int')
tree parmdecl = parms[i];
^
/vol/gcc/src/hg/master/local/gcc/cp/parser.c:30618:28: note: candidate: 'operator[](releasing_vec::vec_t* {aka vec<tree_node*, va_gc>*}, int)' <built-in>
In file included from /vol/gcc/src/hg/master/local/gcc/cp/parser.c:25:
/vol/gcc/src/hg/master/local/gcc/cp/cp-tree.h:965:9: note: candidate: 'tree_node*& releasing_vec::operator[](unsigned int) const'
tree& operator[] (unsigned i) const { return (*v)[i]; }
^~~~~~~~
In file included from /vol/gcc/src/hg/master/local/gcc/c-family/c-common.h:26,
from /vol/gcc/src/hg/master/local/gcc/cp/cp-tree.h:40,
from /vol/gcc/src/hg/master/local/gcc/cp/parser.c:25:
/vol/gcc/src/hg/master/local/gcc/cp/parser.c:30647:24: error: ambiguous overload for 'operator[]' (operand types are 'releasing_vec' and 'int')
DECL_CHAIN (parms[i]) = parm;
^
/vol/gcc/src/hg/master/local/gcc/tree.h:286:26: note: in definition of macro 'CONTAINS_STRUCT_CHECK'
(contains_struct_check ((T), (STRUCT), __FILE__, __LINE__, __FUNCTION__))
^
/vol/gcc/src/hg/master/local/gcc/tree.h:2424:27: note: in expansion of macro 'TREE_CHAIN'
#define DECL_CHAIN(NODE) (TREE_CHAIN (DECL_MINIMAL_CHECK (NODE)))
[...]
Rainer
--
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University
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