- fixed a couple of potential end-less loops

  (no progress in presence of syntax errors)
- end parsing early if source doesn't start
  proper package clause

R=iant
DELTA=18  (7 added, 6 deleted, 5 changed)
OCL=27840
CL=27842

diff --git a/src/lib/go/parser.go b/src/lib/go/parser.go
index f3a5d12336df3645eaa148de49596a1311c61ce2..a1effa6d96c99c00af56eddde56d2386fe692e27 100644 (file)
--- a/src/lib/go/parser.go
+++ b/src/lib/go/parser.go
@@ -38,7 +38,7 @@ type interval struct {
 type parser struct {
        scanner scanner.Scanner;
        err ErrorHandler;  // nil if no handler installed
-       errorCount int;
+       hasErrors bool;
 
        // Tracing/debugging
        mode uint;  // parsing mode
@@ -189,7 +189,7 @@ func (p *parser) error(pos token.Position, msg string) {
        if p.err != nil {
                p.err.Error(pos, msg);
        }
-       p.errorCount++;
+       p.hasErrors = true;
 }
 
 
@@ -297,6 +297,7 @@ func (p *parser) parseType() ast.Expr {
 
        if typ == nil {
                p.error_expected(p.pos, "type");
+               p.next();  // make progress
                return &ast.BadExpr{p.pos};
        }
 
@@ -485,6 +486,7 @@ func (p *parser) parseParameterType(ellipsis_ok bool) ast.Expr {
        typ := p.tryParameterType(ellipsis_ok);
        if typ == nil {
                p.error_expected(p.pos, "type");
+               p.next();  // make progress
                typ = &ast.BadExpr{p.pos};
        }
        return typ;
@@ -1639,6 +1641,7 @@ func (p *parser) parseStatement() ast.Stmt {
 
        // no statement found
        p.error_expected(p.pos, "statement");
+       p.next();  // make progress
        return &ast.BadStmt{p.pos};
 }
 
@@ -1853,14 +1856,12 @@ func (p *parser) parsePackage() *ast.Program {
        comment := p.getDoc();
        pos := p.expect(token.PACKAGE);
        ident := p.parseIdent();
-       if p.tok == token.SEMICOLON {
-               // common error
-               p.error(p.pos, "extra semicolon");
-               p.next();
-       }
-
        var decls []ast.Decl;
-       if p.mode & PackageClauseOnly == 0 {
+
+       // Don't bother parsing the rest if we had errors already.
+       // Likely not a Go source file at all.
+
+       if !p.hasErrors && p.mode & PackageClauseOnly == 0 {
                // import decls
                list := vector.New(0);
                for p.tok == token.IMPORT {
@@ -1960,5 +1961,5 @@ func Parse(src interface{}, err ErrorHandler, mode uint) (*ast.Program, bool) {
        // parse program
        prog := p.parsePackage();
 
-       return prog, p.scanner.ErrorCount == 0 && p.errorCount == 0;
+       return prog, p.scanner.ErrorCount == 0 && !p.hasErrors;
 }