| Message ID | 20201028180248.569437-1-polacek@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: GCC accepts junk before fold-expression [PR86773] | expand |
On 10/28/20 2:02 PM, Marek Polacek wrote: > Here we accept a bogus expression before a left fold: > > Recall that a fold expression looks like: > > fold-expression: > ( cast-expression fold-operator ... ) > ( ... fold-operator cast-expression ) > ( cast-expression fold-operator ... fold-operator cast-expression ) > > but here we have > > ( cast-expression ... fold-operator cast-expression ) > > The best fix seems to just return error_mark_node when we know this code > is invalid, and let the subsequent code report that a ) was expected. It might be nice to suggest how better to write a fold-expression, but it's not necessary. The patch is OK. > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? > > gcc/cp/ChangeLog: > > PR c++/86773 > * parser.c (cp_parser_fold_expression): Return error_mark_node > if a left fold is preceded by an expression. > > gcc/testsuite/ChangeLog: > > PR c++/86773 > * g++.dg/cpp1z/fold12.C: New test. > --- > gcc/cp/parser.c | 2 ++ > gcc/testsuite/g++.dg/cpp1z/fold12.C | 13 +++++++++++++ > 2 files changed, 15 insertions(+) > create mode 100644 gcc/testsuite/g++.dg/cpp1z/fold12.C > > diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c > index cce3d0a679e..1c0eeefe036 100644 > --- a/gcc/cp/parser.c > +++ b/gcc/cp/parser.c > @@ -5138,6 +5138,8 @@ cp_parser_fold_expression (cp_parser *parser, tree expr1) > // Left fold. > if (cp_lexer_next_token_is (parser->lexer, CPP_ELLIPSIS)) > { > + if (expr1) > + return error_mark_node; > cp_lexer_consume_token (parser->lexer); > int op = cp_parser_fold_operator (parser); > if (op == ERROR_MARK) > diff --git a/gcc/testsuite/g++.dg/cpp1z/fold12.C b/gcc/testsuite/g++.dg/cpp1z/fold12.C > new file mode 100644 > index 00000000000..90d74cc5947 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp1z/fold12.C > @@ -0,0 +1,13 @@ > +// PR c++/86773 > +// { dg-do compile { target c++17 } } > + > +template <typename ... Param> > +auto work(Param && ...param) > +{ > + return ("asda" ... / param); // { dg-error "expected" } > +} > + > +int main() > +{ > + work(1.0, 2.0, 5, 4.0); > +} > > base-commit: 2118438f49f0c193abe3fa3def350a8129045746 >
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index cce3d0a679e..1c0eeefe036 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -5138,6 +5138,8 @@ cp_parser_fold_expression (cp_parser *parser, tree expr1) // Left fold. if (cp_lexer_next_token_is (parser->lexer, CPP_ELLIPSIS)) { + if (expr1) + return error_mark_node; cp_lexer_consume_token (parser->lexer); int op = cp_parser_fold_operator (parser); if (op == ERROR_MARK) diff --git a/gcc/testsuite/g++.dg/cpp1z/fold12.C b/gcc/testsuite/g++.dg/cpp1z/fold12.C new file mode 100644 index 00000000000..90d74cc5947 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1z/fold12.C @@ -0,0 +1,13 @@ +// PR c++/86773 +// { dg-do compile { target c++17 } } + +template <typename ... Param> +auto work(Param && ...param) +{ + return ("asda" ... / param); // { dg-error "expected" } +} + +int main() +{ + work(1.0, 2.0, 5, 4.0); +}
Here we accept a bogus expression before a left fold: Recall that a fold expression looks like: fold-expression: ( cast-expression fold-operator ... ) ( ... fold-operator cast-expression ) ( cast-expression fold-operator ... fold-operator cast-expression ) but here we have ( cast-expression ... fold-operator cast-expression ) The best fix seems to just return error_mark_node when we know this code is invalid, and let the subsequent code report that a ) was expected. Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? gcc/cp/ChangeLog: PR c++/86773 * parser.c (cp_parser_fold_expression): Return error_mark_node if a left fold is preceded by an expression. gcc/testsuite/ChangeLog: PR c++/86773 * g++.dg/cpp1z/fold12.C: New test. --- gcc/cp/parser.c | 2 ++ gcc/testsuite/g++.dg/cpp1z/fold12.C | 13 +++++++++++++ 2 files changed, 15 insertions(+) create mode 100644 gcc/testsuite/g++.dg/cpp1z/fold12.C base-commit: 2118438f49f0c193abe3fa3def350a8129045746