-- >8 --
This patch fixes the second half of 64679. Here we issue a wrong
"redefinition of 'int x'" for the following:
struct Bar {
Bar(int, int, int);
};
int x = 1;
Bar bar(int(x), int(x), int{x}); // #1
cp_parser_parameter_declaration_list does pushdecl every time it sees
a named parameter, so the second "int(x)" causes the error. That's
premature, since this turns out to be a constructor call after the
third argument!
If the first parameter is parenthesized, we can't push until we've
established we're looking at a function declaration. Therefore this
could be fixed by some kind of lookahead. I thought about introducing a
lightweight variant of cp_parser_parameter_declaration_list that would
not have any side effects and would return as soon as it figures out
whether it's looking at a declaration or expression. Since that would
require fairly nontrivial changes, I wanted something simpler.
Something like delaying the pushdecl until we've reached the ')'
following the parameter-declaration-clause. But we must push the
parameters before processing a default argument, as in:
Bar bar(int(a), int(b), int c = sizeof(a)); // valid
Moreover, this code should still be accepted
Bar f(int(i), decltype(i) j = 42);
so this patch stashes parameters into a vector when parsing tentatively
only when pushdecl-ing a parameter would result in a clash and an error
about redefinition/redeclaration. The stashed parameters are pushed at
the end of a parameter-declaration-clause if it's followed by a ')', so
that we still diagnose redefining a parameter.
PR c++/64679
gcc/cp/ChangeLog:
* parser.cc (cp_parser_parameter_declaration_clause): Maintain
a vector of parameters that haven't been pushed yet. Push them at the
end of a valid parameter-declaration-clause.
(cp_parser_parameter_declaration_list): Take a new auto_vec parameter.
Do not pushdecl while parsing tentatively when pushdecl-ing a parameter
would result in a hard error.
(cp_parser_cache_defarg): Adjust the call to
cp_parser_parameter_declaration_list.
gcc/testsuite/ChangeLog:
* g++.dg/parse/ambig11.C: New test.
* g++.dg/parse/ambig12.C: New test.
* g++.dg/parse/ambig13.C: New test.
* g++.dg/parse/ambig14.C: New test.
---
gcc/cp/parser.cc | 57 +++++++++++++++++++++++++---
gcc/testsuite/g++.dg/parse/ambig11.C | 39 +++++++++++++++++++
gcc/testsuite/g++.dg/parse/ambig12.C | 12 ++++++
gcc/testsuite/g++.dg/parse/ambig13.C | 32 ++++++++++++++++
gcc/testsuite/g++.dg/parse/ambig14.C | 21 ++++++++++
5 files changed, 156 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/parse/ambig11.C
create mode 100644 gcc/testsuite/g++.dg/parse/ambig12.C
create mode 100644 gcc/testsuite/g++.dg/parse/ambig13.C
create mode 100644 gcc/testsuite/g++.dg/parse/ambig14.C
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index b52cbe18b9a..3ebaa414a3d 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -2391,7 +2391,7 @@ static void cp_parser_type_specifier_seq
static tree cp_parser_parameter_declaration_clause
(cp_parser *, cp_parser_flags);
static tree cp_parser_parameter_declaration_list
- (cp_parser *, cp_parser_flags);
+ (cp_parser *, cp_parser_flags, auto_vec<tree> *);
static cp_parameter_declarator *cp_parser_parameter_declaration
(cp_parser *, cp_parser_flags, bool, bool *);
static tree cp_parser_default_argument
@@ -24517,8 +24517,12 @@ cp_parser_parameter_declaration_clause (cp_parser*
parser,
return explicit_void_list_node;
}
+ /* A vector of parameters that haven't been pushed yet. */
+ auto_vec<tree> pending_decls;
+
/* Parse the parameter-declaration-list. */
- parameters = cp_parser_parameter_declaration_list (parser, flags);
+ parameters = cp_parser_parameter_declaration_list (parser, flags,
+ &pending_decls);
/* If a parse error occurred while parsing the
parameter-declaration-list, then the entire
parameter-declaration-clause is erroneous. */
@@ -24548,6 +24552,15 @@ cp_parser_parameter_declaration_clause (cp_parser*
parser,
else
ellipsis_p = false;
+ /* A valid parameter-declaration-clause can only be followed by a ')'.
+ So it's time to push all the parameters we have seen now that we
+ know we have a valid declaration. Note that here we may not have
+ committed yet, nor should we. Pushing here will detect the error
+ of redefining a parameter. */
+ if (cp_lexer_next_token_is (parser->lexer, CPP_CLOSE_PAREN))
+ for (tree p : pending_decls)
+ pushdecl (p);
+
/* Finish the parameter list. */
if (!ellipsis_p)
parameters = chainon (parameters, void_list_node);
@@ -24562,13 +24575,16 @@ cp_parser_parameter_declaration_clause (cp_parser*
parser,
parameter-declaration-list , parameter-declaration
The parser flags FLAGS is used to control type-specifier parsing.
+ PENDING_DECLS is a vector of parameters that haven't been pushed yet.
Returns a representation of the parameter-declaration-list, as for
cp_parser_parameter_declaration_clause. However, the
`void_list_node' is never appended to the list. */
static tree
-cp_parser_parameter_declaration_list (cp_parser* parser, cp_parser_flags flags)
+cp_parser_parameter_declaration_list (cp_parser* parser,
+ cp_parser_flags flags,
+ auto_vec<tree> *pending_decls)
{
tree parameters = NULL_TREE;
tree *tail = ¶meters;
@@ -24625,7 +24641,37 @@ cp_parser_parameter_declaration_list (cp_parser*
parser, cp_parser_flags flags)
parameter->decl_specifiers.attributes,
0);
if (DECL_NAME (decl))
- decl = pushdecl (decl);
+ {
+ /* We cannot always pushdecl while parsing tentatively because
+ it may have side effects and we can't be sure yet if we're
+ parsing a declaration, e.g.:
+
+ S foo(int(x), int(x), int{x});
+
+ where it's not clear if we're dealing with a constructor call
+ or a function declaration until we've seen the last argument
+ which breaks it up.
+ It's safe to pushdecl so long as it doesn't result in a clash
+ with an already-pushed parameter. But we don't delay pushing
+ different parameters to handle
+
+ S foo(int(i), decltype(i) j = 42);
+
+ which is valid. */
+ if (pending_decls
+ && cp_parser_uncommitted_to_tentative_parse_p (parser)
+ /* See if PARAMETERS already contains a parameter with the same
+ DECL_NAME as DECL. */
+ && [parameters, decl] {
+ for (tree p = parameters; p; p = TREE_CHAIN (p))
+ if (DECL_NAME (decl) == DECL_NAME (TREE_VALUE (p)))
+ return true;
+ return false;
+ }())
+ pending_decls->safe_push (decl);
+ else
+ decl = pushdecl (decl);
+ }
if (decl != error_mark_node)
{
@@ -34072,7 +34118,8 @@ cp_parser_cache_defarg (cp_parser *parser, bool nsdmi)
cp_lexer_consume_token (parser->lexer);
begin_scope (sk_function_parms, NULL_TREE);
tree t = cp_parser_parameter_declaration_list
- (parser, CP_PARSER_FLAGS_NONE);
+ (parser, CP_PARSER_FLAGS_NONE,
+ /*pending_decls*/nullptr);
if (t == error_mark_node)
error = true;
pop_bindings_and_leave_scope ();
diff --git a/gcc/testsuite/g++.dg/parse/ambig11.C
b/gcc/testsuite/g++.dg/parse/ambig11.C
new file mode 100644
index 00000000000..51a586f40b0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/ambig11.C
@@ -0,0 +1,39 @@
+// PR c++/64679
+// { dg-do run { target c++11 } }
+
+struct Bar {
+ int a, b, c;
+ Bar(int a, int b, int c) : a(a), b(b), c(c) { }
+};
+
+void
+f ()
+{
+ Bar fn1(int(a), int(b), int c = sizeof(a));
+ Bar fn2(int(x), int(y), int(z)); // { dg-warning "function declaration" }
+ Bar fn3(int(x), int(y), int);
+ Bar fn4(int (*p)(int(x), int(y))); // { dg-warning "function declaration" }
+ Bar fn5(int (x), int (*p)(int(x), int(y)), int);
+}
+
+int
+main ()
+{
+ int x = 1;
+ // This ain't a decl.
+ Bar v1(int(x), int(x), int{x});
+ if (v1.a != 1 || v1.b != v1.a || v1.c != v1.a)
+ __builtin_abort ();
+ Bar v2(int(x), int(x), 1);
+ if (v2.a != 1 || v2.b != v2.a || v2.c != 1)
+ __builtin_abort ();
+ Bar v3(int(x), int(x), int(1));
+ if (v3.a != 1 || v3.b != v3.a || v3.c != 1)
+ __builtin_abort ();
+ Bar v4(int(1), int(x), int{x});
+ if (v4.a != 1 || v4.b != 1 || v4.c != 1)
+ __builtin_abort ();
+ Bar v5(int{x}, int(x), int{x});
+ if (v5.a != 1 || v5.b != v5.a || v5.c != v5.a)
+ __builtin_abort ();
+}
diff --git a/gcc/testsuite/g++.dg/parse/ambig12.C
b/gcc/testsuite/g++.dg/parse/ambig12.C
new file mode 100644
index 00000000000..981f35f32a2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/ambig12.C
@@ -0,0 +1,12 @@
+// PR c++/64679
+
+struct Bar {
+ Bar (int, int, int);
+};
+
+void
+g ()
+{
+ Bar e1(int(x), int(x), int); // { dg-error "redefinition" }
+ Bar e2(int (*p)(int(x), int(x)), int); // { dg-error "redefinition" }
+}
diff --git a/gcc/testsuite/g++.dg/parse/ambig13.C
b/gcc/testsuite/g++.dg/parse/ambig13.C
new file mode 100644
index 00000000000..5f6a3b934c2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/ambig13.C
@@ -0,0 +1,32 @@
+// PR c++/64679
+// { dg-do compile { target c++11 } }
+
+struct Bar {
+ Bar (int, int, int);
+};
+
+template<typename T>
+void
+g ()
+{
+ int x = 1;
+ Bar v1(T(x), T(x), T{x});
+ Bar v2(T(x), T(x), T(1));
+}
+
+void
+invoke (Bar (*p)) noexcept(noexcept(*p))
+{
+}
+
+auto
+pmf (int (Bar::*p)) -> decltype(p)
+{
+ return nullptr;
+}
+
+void
+f ()
+{
+ g<int>();
+}
diff --git a/gcc/testsuite/g++.dg/parse/ambig14.C
b/gcc/testsuite/g++.dg/parse/ambig14.C
new file mode 100644
index 00000000000..0305596a835
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/ambig14.C
@@ -0,0 +1,21 @@
+// PR c++/64679
+// { dg-do compile { target c++11 } }
+
+struct F {
+ F(int, int);
+};
+
+void
+g ()
+{
+ int x = 42;
+
+ F v1(int(x), decltype(x)(42));
+
+ F f1(int(i), decltype(i) j = 42);
+ F f2(int(i), decltype(i) j);
+ F f3(int(i), decltype(i)(j)); // { dg-warning "function declaration" }
+ F f4(int(i), decltype(i)(j) = 42); // { dg-warning "function declaration" }
+ F f5(int (i), bool b = true, decltype(i) j = 42);
+ F f6(int(i), decltype(x)(x)); // { dg-warning "function declaration" }
+}
base-commit: b06a79b82366a53fffc113f3bb5f873dbc70e381
