Auto merge of #29780 - KyleMayes:quote-ext, r=nrc

This is my first code contribution to Rust, so I'm sure there are some issues with the changes I've made.

I've added the `quote_arg!`, `quote_block!`, `quote_path!`, and `quote_meta_item!` quasiquoting macros. From my experience trying to build AST in compiler plugins, I would like to be able to build any AST piece with a quasiquoting macro (e.g., `quote_struct_field!` or `quote_variant!`) and then use those AST pieces in other quasiquoting macros, but this pull request just adds some of the low-hanging fruit.

I'm not sure if these additions are desirable, and I'm sure these macros can be implemented in an external crate if not.

1 files changed, 18 insertions, 0 deletions

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 1e38eebec5d..9219f05d99a 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -393,6 +393,22 @@ impl<'a> Parser<'a> {
         panictry!(self.parse_attribute(permit_inner))
     }
 
+    pub fn parse_arg_panic(&mut self) -> Arg {
+        panictry!(self.parse_arg())
+    }
+
+    pub fn parse_block_panic(&mut self) -> P<Block> {
+        panictry!(self.parse_block())
+    }
+
+    pub fn parse_meta_item_panic(&mut self) -> P<ast::MetaItem> {
+        panictry!(self.parse_meta_item())
+    }
+
+    pub fn parse_path_panic(&mut self, mode: PathParsingMode) -> ast::Path {
+        panictry!(self.parse_path(mode))
+    }
+
     /// Convert a token to a string using self's reader
     pub fn token_to_string(token: &token::Token) -> String {
         pprust::token_to_string(token)
@@ -1455,6 +1471,8 @@ impl<'a> Parser<'a> {
     /// This version of parse arg doesn't necessarily require
     /// identifier names.
     pub fn parse_arg_general(&mut self, require_name: bool) -> PResult<Arg> {
+        maybe_whole!(no_clone self, NtArg);
+
         let pat = if require_name || self.is_named_argument() {
             debug!("parse_arg_general parse_pat (require_name:{})",
                    require_name);