[PATCH,c++] fix PR 4452{2,3}, autocorrect colon to scopes when appropriate
Nathan Froyd
froydnj@codesourcery.com
Wed Dec 8 21:31:00 GMT 2010
The patch below addresses PRs 44522 and 44523, which both request that a
colon in a nested-name-specifier be auto-corrected to a scope (::). The
implementation below adds a flag to cp_parser indicating whether it's
valid to do that. The flag defaults to "yes, it's valid" and gets
turned off when parsing certain productions (e.g. parsing case labels,
or parsing the start of class declarations).
The idea is pretty simple; most of the hair in the patch below involves
making sure that functions where we temporarily set
colon_corrects_to_scope_p exit through a single point, where we can then
reset colon_corrects_to_scope_p. I'm happy to leave the code the way it
is and duplicate the resetting at appropriate return points if the
maintainers think that would be a better idea.
Ideas on improvements would be welcome; I went for the approach of
making sure the testcases work (and trying out a few other cases) and
making sure the testsuites pass. My C++ is pretty weak, so there's
probably interesting cases that I don't catch.
Tested on x86_64-unknown-linux-gnu (g++ and libstdc++ testsuites). OK
to commit?
-Nathan
gcc/cp/
PR c++/44522
PR c++/44523
* parser.c (struct cp_parser): Add colon_corrects_to_scope_p field.
(cp_parser_new): Initialize it.
(cp_parser_nested_name_specifier_opt): Auto-correct colons to
scopes if we are able to.
(cp_parser_question_colon_clause): Disallow colon correction.
(cp_parser_label_for_labeled_statement): Likewise.
(cp_parser_range_for): Likewise.
(cp_parser_enum_specifier): Likewise.
(cp_parser_class_head): Likewise.
(cp_parser_member_declaration): Likewise.
gcc/testsuite/
PR c++/44522
PR c++/44523
* g++.dg/parse/colon-autocorrect-1.C: New testcase.
* g++.dg/parse/colon-autocorrect-2.C: New testcase.
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index ab533f4..b31bf01 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -1700,6 +1700,9 @@ typedef struct GTY(()) cp_parser {
a local class. */
bool in_function_body;
+ /* TRUE if we can auto-correct a colon to a scope operator. */
+ bool colon_corrects_to_scope_p;
+
/* If non-NULL, then we are parsing a construct where new type
definitions are not permitted. The string stored here will be
issued as an error message if a type is defined. */
@@ -3244,6 +3247,9 @@ cp_parser_new (void)
/* We are not parsing a function body. */
parser->in_function_body = false;
+ /* We can correct until told otherwise. */
+ parser->colon_corrects_to_scope_p = true;
+
/* The unparsed function queue is empty. */
push_unparsed_function_queues (parser);
@@ -4553,6 +4559,16 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser,
template-id), nor a `::', then we are not looking at a
nested-name-specifier. */
token = cp_lexer_peek_nth_token (parser->lexer, 2);
+
+ if (token->type == CPP_COLON
+ && parser->colon_corrects_to_scope_p
+ && cp_lexer_peek_nth_token (parser->lexer, 3)->type == CPP_NAME)
+ {
+ error_at (token->location,
+ "found %<:%> in nested-name-specifier, expected %<::%>");
+ token->type = CPP_SCOPE;
+ }
+
if (token->type != CPP_SCOPE
&& !cp_parser_nth_token_starts_template_argument_list_p
(parser, 2))
@@ -6955,12 +6971,15 @@ cp_parser_question_colon_clause (cp_parser* parser, tree logical_or_expr)
}
else
{
+ bool saved_colon_corrects_to_scope_p = parser->colon_corrects_to_scope_p;
+ parser->colon_corrects_to_scope_p = false;
/* Parse the expression. */
c_inhibit_evaluation_warnings += logical_or_expr == truthvalue_false_node;
expr = cp_parser_expression (parser, /*cast_p=*/false, NULL);
c_inhibit_evaluation_warnings +=
((logical_or_expr == truthvalue_true_node)
- (logical_or_expr == truthvalue_false_node));
+ parser->colon_corrects_to_scope_p = saved_colon_corrects_to_scope_p;
}
/* The next token should be a `:'. */
@@ -8153,6 +8172,7 @@ cp_parser_label_for_labeled_statement (cp_parser* parser)
{
cp_token *token;
tree label = NULL_TREE;
+ bool saved_colon_corrects_to_scope_p = parser->colon_corrects_to_scope_p;
/* The next token should be an identifier. */
token = cp_lexer_peek_token (parser->lexer);
@@ -8163,6 +8183,7 @@ cp_parser_label_for_labeled_statement (cp_parser* parser)
return;
}
+ parser->colon_corrects_to_scope_p = false;
switch (token->keyword)
{
case RID_CASE:
@@ -8241,6 +8262,8 @@ cp_parser_label_for_labeled_statement (cp_parser* parser)
else
cplus_decl_attributes (&label, attrs, 0);
}
+
+ parser->colon_corrects_to_scope_p = saved_colon_corrects_to_scope_p;
}
/* Parse an expression-statement.
@@ -8710,7 +8733,9 @@ cp_parser_range_for (cp_parser *parser)
cp_declarator *declarator;
const char *saved_message;
tree attributes, pushed_scope;
+ bool saved_colon_corrects_to_scope_p = parser->colon_corrects_to_scope_p;
+ parser->colon_corrects_to_scope_p = false;
cp_parser_parse_tentatively (parser);
/* New types are not allowed in the type-specifier-seq for a
range-based for loop. */
@@ -8727,7 +8752,8 @@ cp_parser_range_for (cp_parser *parser)
if (cp_parser_error_occurred (parser))
{
cp_parser_abort_tentative_parse (parser);
- return NULL_TREE;
+ stmt = NULL_TREE;
+ goto out;
}
/* Parse the declarator. */
declarator = cp_parser_declarator (parser, CP_PARSER_DECLARATOR_NAMED,
@@ -8774,6 +8800,8 @@ cp_parser_range_for (cp_parser *parser)
/* Convert the range-based for loop into a normal for-statement. */
stmt = cp_convert_range_for (stmt, range_decl, range_expr);
+ out:
+ parser->colon_corrects_to_scope_p = saved_colon_corrects_to_scope_p;
return stmt;
}
@@ -13343,6 +13371,9 @@ cp_parser_enum_specifier (cp_parser* parser)
bool is_anonymous = false;
tree underlying_type = NULL_TREE;
cp_token *type_start_token = NULL;
+ bool saved_colon_corrects_to_scope_p = parser->colon_corrects_to_scope_p;
+
+ parser->colon_corrects_to_scope_p = false;
/* Parse tentatively so that we can back up if we don't find a
enum-specifier. */
@@ -13470,7 +13501,10 @@ cp_parser_enum_specifier (cp_parser* parser)
{
cp_parser_error (parser, "expected %<{%>");
if (has_underlying_type)
- return NULL_TREE;
+ {
+ type = NULL_TREE;
+ goto out;
+ }
}
/* An opaque-enum-specifier must have a ';' here. */
if ((scoped_enum_p || underlying_type)
@@ -13478,7 +13512,10 @@ cp_parser_enum_specifier (cp_parser* parser)
{
cp_parser_error (parser, "expected %<;%> or %<{%>");
if (has_underlying_type)
- return NULL_TREE;
+ {
+ type = NULL_TREE;
+ goto out;
+ }
}
}
@@ -13622,6 +13659,8 @@ cp_parser_enum_specifier (cp_parser* parser)
pop_nested_namespace (nested_name_specifier);
}
}
+ out:
+ parser->colon_corrects_to_scope_p = saved_colon_corrects_to_scope_p;
return type;
}
@@ -17085,6 +17124,7 @@ cp_parser_class_head (cp_parser* parser,
bool qualified_p = false;
bool invalid_nested_name_p = false;
bool invalid_explicit_specialization_p = false;
+ bool saved_colon_corrects_to_scope_p = parser->colon_corrects_to_scope_p;
tree pushed_scope = NULL_TREE;
unsigned num_templates;
cp_token *type_start_token = NULL, *nested_name_specifier_token_start = NULL;
@@ -17093,6 +17133,7 @@ cp_parser_class_head (cp_parser* parser,
/* Assume no template parameter lists will be used in defining the
type. */
num_templates = 0;
+ parser->colon_corrects_to_scope_p = false;
*bases = NULL_TREE;
@@ -17232,7 +17273,8 @@ cp_parser_class_head (cp_parser* parser,
if (!cp_parser_next_token_starts_class_definition_p (parser))
{
cp_parser_error (parser, "expected %<{%> or %<:%>");
- return error_mark_node;
+ type = error_mark_node;
+ goto out;
}
/* At this point, we're going ahead with the class-specifier, even
@@ -17243,13 +17285,15 @@ cp_parser_class_head (cp_parser* parser,
{
cp_parser_error (parser,
"global qualification of class name is invalid");
- return error_mark_node;
+ type = error_mark_node;
+ goto out;
}
else if (invalid_nested_name_p)
{
cp_parser_error (parser,
"qualified name does not name a class");
- return error_mark_node;
+ type = error_mark_node;
+ goto out;
}
else if (nested_name_specifier)
{
@@ -17452,6 +17496,8 @@ cp_parser_class_head (cp_parser* parser,
if (type)
DECL_SOURCE_LOCATION (TYPE_NAME (type)) = type_start_token->location;
*attributes_p = attributes;
+ out:
+ parser->colon_corrects_to_scope_p = saved_colon_corrects_to_scope_p;
return type;
}
@@ -17580,6 +17626,7 @@ cp_parser_member_declaration (cp_parser* parser)
cp_token *decl_spec_token_start = NULL;
cp_token *initializer_token_start = NULL;
int saved_pedantic;
+ bool saved_colon_corrects_to_scope_p = parser->colon_corrects_to_scope_p;
/* Check for the `__extension__' keyword. */
if (cp_parser_extension_opt (parser, &saved_pedantic))
@@ -17638,8 +17685,10 @@ cp_parser_member_declaration (cp_parser* parser)
return;
}
+ parser->colon_corrects_to_scope_p = false;
+
if (cp_parser_using_declaration (parser, /*access_declaration=*/true))
- return;
+ goto out;
/* Parse the decl-specifier-seq. */
decl_spec_token_start = cp_lexer_peek_token (parser->lexer);
@@ -17652,7 +17701,7 @@ cp_parser_member_declaration (cp_parser* parser)
/* Check for an invalid type-name. */
if (!decl_specifiers.any_type_specifiers_p
&& cp_parser_parse_and_diagnose_invalid_type_name (parser))
- return;
+ goto out;
/* If there is no declarator, then the decl-specifier-seq should
specify a type. */
if (cp_lexer_next_token_is (parser->lexer, CPP_SEMICOLON))
@@ -17822,7 +17871,7 @@ cp_parser_member_declaration (cp_parser* parser)
if (cp_lexer_next_token_is (parser->lexer,
CPP_SEMICOLON))
cp_lexer_consume_token (parser->lexer);
- return;
+ goto out;
}
if (declares_class_or_enum & 2)
@@ -17901,7 +17950,7 @@ cp_parser_member_declaration (cp_parser* parser)
/* If the next token is a semicolon, consume it. */
if (token->type == CPP_SEMICOLON)
cp_lexer_consume_token (parser->lexer);
- return;
+ goto out;
}
else
if (declarator->kind == cdk_function)
@@ -17956,11 +18005,13 @@ cp_parser_member_declaration (cp_parser* parser)
}
if (assume_semicolon)
- return;
+ goto out;
}
}
cp_parser_require (parser, CPP_SEMICOLON, RT_SEMICOLON);
+ out:
+ parser->colon_corrects_to_scope_p = saved_colon_corrects_to_scope_p;
}
/* Parse a pure-specifier.
diff --git a/gcc/testsuite/g++.dg/parse/colon-autocorrect-1.C b/gcc/testsuite/g++.dg/parse/colon-autocorrect-1.C
new file mode 100644
index 0000000..8e25fba
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/colon-autocorrect-1.C
@@ -0,0 +1,31 @@
+// PR c++/44522
+// { dg-do compile }
+
+namespace x {
+ struct a { };
+ a A0;
+}
+
+x:a a2; // { dg-error "nested-name-specifier" }
+x::a a3 = a2;
+
+x:a f (void) // { dg-error "nested-name-specifier" }
+{
+ x::a a4; // x:a would parse like a label
+ return a4;
+}
+
+x::a g (x:a a4) // { dg-error "nested-name-specifier" }
+{
+ return a4;
+}
+
+class B
+{
+ x::a f(void) // x:a would parse like a bitfield
+ {
+ x::a a4;
+ a4 = x:A0; // { dg-error "nested-name-specifier" }
+ return a4;
+ }
+};
diff --git a/gcc/testsuite/g++.dg/parse/colon-autocorrect-2.C b/gcc/testsuite/g++.dg/parse/colon-autocorrect-2.C
new file mode 100644
index 0000000..1dfcbc0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/colon-autocorrect-2.C
@@ -0,0 +1,15 @@
+// PR c++/44523
+// { dg-do compile }
+
+namespace x {
+ struct a { };
+}
+
+template <typename t>
+class foo {
+};
+
+foo<x::a> a1;
+foo<x:a> a2; // { dg-error "nested-name-specifier" }
+
+x::a a3 = a2; // { dg-error "conversion" }
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