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From: Thomas Schwinge <tschwinge@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc/devel/rust/master] parser: Allow parsing of qualified type path as nested generic argument Date: Wed, 22 Feb 2023 07:22:41 +0000 (GMT) [thread overview] Message-ID: <20230222072241.57284385841E@sourceware.org> (raw) https://gcc.gnu.org/g:57b64a64261ed1d1774af61a1e36eeac604abcde commit 57b64a64261ed1d1774af61a1e36eeac604abcde Author: Arthur Cohen <arthur.cohen@embecosm.com> Date: Thu Feb 16 13:53:22 2023 +0100 parser: Allow parsing of qualified type path as nested generic argument Let's take the example of lexing `Option<<T as Iterator>::Item>` and look at the first few tokens. Originally, `Option<<T` was lexed as 3 tokens: * IDENTIFIER(Option) * LEFT_SHIFT * IDENTIFIER(T) The parser did not allow a list of generic arguments to start with a left shift, and rejected the above type. We are now splitting the left shift into two left angles, as this allows complex generic arguments and overall makes sense parsing wise. Thus, the above list becomes: * IDENTIFIER(Option) * LEFT_ANGLE * LEFT_ANGLE * IDENTIFIER(T) and `<T as Iterator>` is properly parsed as a qualified path. Fixes #1815 Fixed #1809 Addresses #1524 gcc/rust/ChangeLog: * parse/rust-parse-impl.h (Parser::parse_path_generic_args): Split leading `LEFT_SHIFT` token into two `LEFT_ANGLE` tokens when parsing generic arguments. (Parser::parse_type_path_segment): Allow `LEFT_ANGLE` as starting token for parsing generic arguments. gcc/testsuite/ChangeLog: * rust/compile/parse_associated_type_as_generic_arg.rs: New test. * rust/compile/parse_associated_type_as_generic_arg2.rs: New test. * rust/compile/path_as_generic_arg.rs: New test. * rust/compile/nested_generic.rs: New test. Diff: --- gcc/rust/parse/rust-parse-impl.h | 4 ++++ gcc/testsuite/rust/compile/nested_generic.rs | 4 ++++ .../parse_associated_type_as_generic_arg.rs | 24 ++++++++++++++++++++++ .../parse_associated_type_as_generic_arg2.rs | 24 ++++++++++++++++++++++ gcc/testsuite/rust/compile/path_as_generic_arg.rs | 12 +++++++++++ 5 files changed, 68 insertions(+) diff --git a/gcc/rust/parse/rust-parse-impl.h b/gcc/rust/parse/rust-parse-impl.h index 4c39284749d..3bf26bc6fdc 100644 --- a/gcc/rust/parse/rust-parse-impl.h +++ b/gcc/rust/parse/rust-parse-impl.h @@ -6383,6 +6383,9 @@ template <typename ManagedTokenSource> AST::GenericArgs Parser<ManagedTokenSource>::parse_path_generic_args () { + if (lexer.peek_token ()->get_id () == LEFT_SHIFT) + lexer.split_current_token (LEFT_ANGLE, LEFT_ANGLE); + if (!skip_token (LEFT_ANGLE)) { // skip after somewhere? @@ -6557,6 +6560,7 @@ Parser<ManagedTokenSource>::parse_type_path_segment () const_TokenPtr t = lexer.peek_token (); switch (t->get_id ()) { + case LEFT_SHIFT: case LEFT_ANGLE: { // parse generic args AST::GenericArgs generic_args = parse_path_generic_args (); diff --git a/gcc/testsuite/rust/compile/nested_generic.rs b/gcc/testsuite/rust/compile/nested_generic.rs new file mode 100644 index 00000000000..6c3109957f9 --- /dev/null +++ b/gcc/testsuite/rust/compile/nested_generic.rs @@ -0,0 +1,4 @@ +pub struct A<T>(T); +pub struct B<T>(T); + +pub fn foo(_: A<B<i32>>) {} diff --git a/gcc/testsuite/rust/compile/parse_associated_type_as_generic_arg.rs b/gcc/testsuite/rust/compile/parse_associated_type_as_generic_arg.rs new file mode 100644 index 00000000000..dc05c068359 --- /dev/null +++ b/gcc/testsuite/rust/compile/parse_associated_type_as_generic_arg.rs @@ -0,0 +1,24 @@ +// { dg-additional-options "-fsyntax-only" } + +trait Foo { + type A; + + fn foo(); +} + +struct S; + +impl Foo for S { + type A = i32; + + fn foo() {} +} + +enum Maybe<T> { + Something(T), + Nothing, +} + +fn foo() -> Maybe<<S as Foo>::A> { + Maybe::Something(15) +} diff --git a/gcc/testsuite/rust/compile/parse_associated_type_as_generic_arg2.rs b/gcc/testsuite/rust/compile/parse_associated_type_as_generic_arg2.rs new file mode 100644 index 00000000000..9c518a03ca7 --- /dev/null +++ b/gcc/testsuite/rust/compile/parse_associated_type_as_generic_arg2.rs @@ -0,0 +1,24 @@ +// { dg-additional-options "-fsyntax-only" } + +trait Foo { + type A; + + fn foo(); +} + +struct S; + +impl Foo for S { + type A = (); + + fn foo() {} +} + +enum Maybe<T> { + Something(T), + Nothing, +} + +fn main() { + let a: Maybe<<S as Foo>::A> = Maybe::Something(()); +} diff --git a/gcc/testsuite/rust/compile/path_as_generic_arg.rs b/gcc/testsuite/rust/compile/path_as_generic_arg.rs new file mode 100644 index 00000000000..35b3160e9a8 --- /dev/null +++ b/gcc/testsuite/rust/compile/path_as_generic_arg.rs @@ -0,0 +1,12 @@ +pub enum Result<T, E> { + Ok(T), + Err(E), +} + +pub mod module { + pub struct E; +} + +pub fn foo() -> Result<(), module::E> { + Result::Err(module::E) +}
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