Auto merge of #30654 - nrc:panictry, r=brson

The motivation (other than removing boilerplate) is that this is a baby step towards a parser with error recovery.

[breaking-change] if you use any of the changed functions, you'll need to remove a try! or panictry!

Author: bors

src/libsyntax/ext/base.rs

@@ -826,7 +826,7 @@ pub fn get_exprs_from_tts(cx: &mut ExtCtxt,
     let mut es = Vec::new();
     while p.token != token::Eof {
         es.push(cx.expander().fold_expr(panictry!(p.parse_expr())));
-        if panictry!(p.eat(&token::Comma)){
+        if p.eat(&token::Comma) {
             continue;
         }
         if p.token != token::Eof {

src/libsyntax/ext/quote.rs

@@ -801,7 +801,7 @@ fn parse_arguments_to_quote(cx: &ExtCtxt, tts: &[TokenTree])
     p.quote_depth += 1;
 
     let cx_expr = panictry!(p.parse_expr());
-    if !panictry!(p.eat(&token::Comma)) {
+    if !p.eat(&token::Comma) {
         let _ = p.diagnostic().fatal("expected token `,`");
     }
 

src/libsyntax/ext/tt/macro_parser.rs

@@ -512,7 +512,7 @@ pub fn parse_nt<'a>(p: &mut Parser<'a>, sp: Span, name: &str) -> Nonterminal {
         _ => {}
     }
     // check at the beginning and the parser checks after each bump
-    panictry!(p.check_unknown_macro_variable());
+    p.check_unknown_macro_variable();
     match name {
         "item" => match panictry!(p.parse_item()) {
             Some(i) => token::NtItem(i),
@@ -535,7 +535,7 @@ pub fn parse_nt<'a>(p: &mut Parser<'a>, sp: Span, name: &str) -> Nonterminal {
         // this could be handled like a token, since it is one
         "ident" => match p.token {
             token::Ident(sn,b) => {
-                panictry!(p.bump());
+                p.bump();
                 token::NtIdent(Box::new(Spanned::<Ident>{node: sn, span: p.span}),b)
             }
             _ => {

src/libsyntax/ext/tt/macro_rules.rs

@@ -47,7 +47,7 @@ impl<'a> ParserAnyMacro<'a> {
     fn ensure_complete_parse(&self, allow_semi: bool, context: &str) {
         let mut parser = self.parser.borrow_mut();
         if allow_semi && parser.token == token::Semi {
-            panictry!(parser.bump())
+            parser.bump();
         }
         if parser.token != token::Eof {
             let token_str = parser.this_token_to_string();
@@ -194,7 +194,7 @@ fn generic_extension<'cx>(cx: &'cx ExtCtxt,
                                            imported_from,
                                            rhs);
                 let mut p = Parser::new(cx.parse_sess(), cx.cfg(), Box::new(trncbr));
-                panictry!(p.check_unknown_macro_variable());
+                p.check_unknown_macro_variable();
                 // Let the context choose how to interpret the result.
                 // Weird, but useful for X-macros.
                 return Box::new(ParserAnyMacro {

src/libsyntax/parse/attr.rs

@@ -39,7 +39,7 @@ impl<'a> Parser<'a> {
                   return Err(self.fatal("expected outer comment"));
                 }
                 attrs.push(attr);
-                try!(self.bump());
+                self.bump();
               }
               _ => break
             }
@@ -57,11 +57,11 @@ impl<'a> Parser<'a> {
         let (span, value, mut style) = match self.token {
             token::Pound => {
                 let lo = self.span.lo;
-                try!(self.bump());
+                self.bump();
 
                 if permit_inner { self.expected_tokens.push(TokenType::Token(token::Not)); }
                 let style = if self.token == token::Not {
-                    try!(self.bump());
+                    self.bump();
                     if !permit_inner {
                         let span = self.span;
                         self.diagnostic().struct_span_err(span,
@@ -91,7 +91,7 @@ impl<'a> Parser<'a> {
         };
 
         if permit_inner && self.token == token::Semi {
-            try!(self.bump());
+            self.bump();
             self.span_warn(span, "this inner attribute syntax is deprecated. \
                            The new syntax is `#![foo]`, with a bang and no semicolon");
             style = ast::AttrStyle::Inner;
@@ -134,7 +134,7 @@ impl<'a> Parser<'a> {
                     let attr = attr::mk_sugared_doc_attr(attr::mk_attr_id(), str, lo, hi);
                     if attr.node.style == ast::AttrStyle::Inner {
                         attrs.push(attr);
-                        try!(self.bump());
+                        self.bump();
                     } else {
                         break;
                     }
@@ -158,7 +158,7 @@ impl<'a> Parser<'a> {
 
         match nt_meta {
             Some(meta) => {
-                try!(self.bump());
+                self.bump();
                 return Ok(meta);
             }
             None => {}
@@ -169,7 +169,7 @@ impl<'a> Parser<'a> {
         let name = self.id_to_interned_str(ident);
         match self.token {
             token::Eq => {
-                try!(self.bump());
+                self.bump();
                 let lit = try!(self.parse_lit());
                 // FIXME #623 Non-string meta items are not serialized correctly;
                 // just forbid them for now

src/libsyntax/parse/mod.rs

@@ -261,7 +261,7 @@ pub fn tts_to_parser<'a>(sess: &'a ParseSess,
                          cfg: ast::CrateConfig) -> Parser<'a> {
     let trdr = lexer::new_tt_reader(&sess.span_diagnostic, None, None, tts);
     let mut p = Parser::new(sess, cfg, Box::new(trdr));
-    panictry!(p.check_unknown_macro_variable());
+    p.check_unknown_macro_variable();
     p
 }