</p>

<pre class="ebnf">
SourceFile       = PackageClause ";" { ImportDecl ";" } { TopLevelDecl ";" } .
</pre>

<h3 id="Package_clause">Package clause</h3>

<p>
A package clause begins each source file and defines the package
to which the file belongs.
</p>

<pre class="ebnf">
PackageClause  = "package" PackageName .
PackageName    = identifier .
</pre>

<p>

</p>

<pre class="ebnf">
SourceFile       = PackageClause ";" { ImportDecl ";" } { TopLevelDecl ";" } .
</pre>

<h3 id="Package_clause">Package clause</h3>

<p>
A package clause begins each source file and defines the package
to which the file belongs.
</p>

<pre class="ebnf">
PackageClause  = "package" PackageName .
PackageName    = identifier .
</pre>

<p>

	bytes.Buffer
}

func (pb *pkgBuffer) Write(p []byte) (int, error) {
	pb.packageClause()
	return pb.Buffer.Write(p)
}

func (pb *pkgBuffer) packageClause() {
	if !pb.printed {
		pb.printed = true
		// Only show package clause for commands if requested explicitly.
		if pb.pkg.pkg.Name != "main" || showCmd {
			pb.pkg.packageClause()
		}
	}
}

type PackageError string // type returned by pkg.Fatalf.

// nil; all others are expected to return a valid non-nil node.

// SourceFile = PackageClause ";" { ImportDecl ";" } { TopLevelDecl ";" } .
func (p *parser) fileOrNil() *File {
	if trace {
		defer p.trace("file")()
	}

	f := new(File)
	f.pos = p.pos()

	// PackageClause
	f.GoVersion = p.goVersion
	p.top = false
	if !p.got(_Package) {