cmd/compile: address several more 1.6 TODOs in parser

- fix/check location of popdcl calls where questioned
- remove unnecessary handling of ... (LDDD) in ntype (couldn't be reached)
- inlined and fnret_type and simplified fnres as a consequence
- leave handling of ... (LDDD) in arg_list alone (remove TODO)
- verify that parser requires a ';' after last statement in a case/default
  (added test case)

Fixes #13243.

Change-Id: Iad94b498591a5e85f4cb15bbc01e8e101415560d
Reviewed-on: https://go-review.googlesource.com/17155
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Chris Manghane <cmang@golang.org>

diff --git a/src/cmd/compile/internal/gc/parser.go b/src/cmd/compile/internal/gc/parser.go
index 7244e44654bfbda57fec29f0e78e69f76bc0fc91..85abca11c80bfda6e42442ed3736fe75b53347c8 100644 (file)
--- a/src/cmd/compile/internal/gc/parser.go
+++ b/src/cmd/compile/internal/gc/parser.go
@@ -225,11 +225,9 @@ func tokstring(tok int32) string {
                return s
        }
        // catchall
-       return yyTokname(int(tok))
+       return fmt.Sprintf("tok-%v", tok)
 }
 
-// TODO(gri) figure out why yyTokname doesn't work for us as expected
-// (issue 13243)
 var tokstrings = map[int32]string{
        LLITERAL:           "LLITERAL",
        LASOP:              "op=",
@@ -439,7 +437,7 @@ func (p *parser) import_here() int {
                p.advance(';', ')')
        }
 
-       line := parserline() // TODO(gri) check correct placement of this (issue 13243)
+       line := parserline()
        importfile(&path, line)
        return line
 }
@@ -899,6 +897,7 @@ func (p *parser) compound_stmt(else_clause bool) *Node {
        }
 
        l := p.stmt_list()
+       p.want('}')
 
        var stmt *Node
        if l == nil {
@@ -908,8 +907,6 @@ func (p *parser) compound_stmt(else_clause bool) *Node {
        }
        popdcl()
 
-       p.want('}') // TODO(gri) is this correct location w/ respect to popdcl()? (issue 13243)
-
        return stmt
 }
 
@@ -920,32 +917,9 @@ func (p *parser) caseblock(tswitch *Node) *Node {
        }
 
        stmt := p.case_(tswitch) // does markdcl
-
-       // If the last token read by the lexer was consumed
-       // as part of the case, clear it (parser has cleared yychar).
-       // If the last token read by the lexer was the lookahead
-       // leave it alone (parser has it cached in yychar).
-       // This is so that the stmt_list action doesn't look at
-       // the case tokens if the stmt_list is empty.
-       //yylast = yychar;
        stmt.Xoffset = int64(block)
-
        stmt.Nbody = p.stmt_list()
 
-       // TODO(gri) what do we need to do here? (issue 13243)
-       // // This is the only place in the language where a statement
-       // // list is not allowed to drop the final semicolon, because
-       // // it's the only place where a statement list is not followed
-       // // by a closing brace.  Handle the error for pedantry.
-
-       // // Find the final token of the statement list.
-       // // yylast is lookahead; yyprev is last of stmt_list
-       // last := yyprev;
-
-       // if last > 0 && last != ';' && yychar != '}' {
-       //      Yyerror("missing statement after label");
-       // }
-
        popdcl()
 
        return stmt
@@ -1873,14 +1847,6 @@ func (p *parser) ntype() *Node {
                p.want(')')
                return t
 
-       case LDDD:
-               // permit ...T but complain
-               // TODO(gri) introduced for test/fixedbugs/bug228.go - maybe adjust bug or find better solution
-               // (issue 13243)
-               p.syntax_error("")
-               p.advance()
-               return p.ntype()
-
        default:
                p.syntax_error("")
                p.advance()
@@ -1898,8 +1864,7 @@ func (p *parser) chan_elem() *Node {
                '[', LCHAN, LMAP, LSTRUCT, LINTERFACE,
                '*',
                LNAME, '@', '?',
-               '(',
-               LDDD:
+               '(':
                return p.ntype()
 
        default:
@@ -1909,26 +1874,6 @@ func (p *parser) chan_elem() *Node {
        }
 }
 
-// go.y:fnret_type
-// TODO(gri) only called from fnres - inline and remove this one
-// (issue 13243)
-func (p *parser) fnret_type() *Node {
-       if trace && Debug['x'] != 0 {
-               defer p.trace("fnret_type")()
-       }
-
-       switch p.tok {
-       case LFUNC, // fntype
-               LCOMM,                                 // recvchantype
-               '[', LCHAN, LMAP, LSTRUCT, LINTERFACE, // othertype
-               '*': // ptrtype
-               return p.ntype()
-
-       default:
-               return p.dotname()
-       }
-}
-
 // go.y:dotname (partial)
 func (p *parser) new_dotname(pkg *Node) *Node {
        if trace && Debug['x'] != 0 {
@@ -2218,7 +2163,7 @@ func (p *parser) fnres() *NodeList {
                return nil
 
        case LCOMM, LFUNC, '[', LCHAN, LMAP, LSTRUCT, LINTERFACE, '*', LNAME, '@', '?':
-               result := p.fnret_type()
+               result := p.ntype()
                return list1(Nod(ODCLFIELD, nil, result))
 
        case '(':
@@ -2754,9 +2699,6 @@ func (p *parser) arg_list() (l *NodeList, ddd bool) {
                defer p.trace("arg_list")()
        }
 
-       // TODO(gri) make this more tolerant in the presence of LDDD
-       // that is not at the end (issue 13243).
-
        p.want('(')
        p.xnest++
 

diff --git a/test/switch2.go b/test/switch2.go
index 3582da8be6d16c1cf6fcca3ea56e0e8baa28a3b5..11ff5c5d9b95c275e81ff965245a71b9e1d5e19d 100644 (file)
--- a/test/switch2.go
+++ b/test/switch2.go
@@ -4,11 +4,12 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Check various syntax errors with switches.
+// Verify that erroneous switch statements are detected by the compiler.
+// Does not compile.
 
 package main
 
-func _() {
+func f() {
        switch {
        case 0; // ERROR "expecting := or = or : or comma"
        }
@@ -18,6 +19,20 @@ func _() {
        default:
        }
 
+       switch {
+       case 0: case 0: default:
+       }
+
+       switch {
+       case 0: f(); case 0:
+       case 0: f() case 0: // ERROR "unexpected case at end of statement"
+       }
+
+       switch {
+       case 0: f(); default:
+       case 0: f() default: // ERROR "unexpected default at end of statement"
+       }
+
        switch {
        if x: // ERROR "expecting case or default or }"
        }