go/printer: make tests follow syntactic restrictions

R=rsc
CC=golang-dev
http://codereview.appspot.com/4439087

3 files changed, 174 insertions, 117 deletions

diff --git a/src/pkg/go/printer/testdata/expressions.golden b/src/pkg/go/printer/testdata/expressions.golden
index c1a7e970b..3d0f144e1 100644
--- a/src/pkg/go/printer/testdata/expressions.golden
+++ b/src/pkg/go/printer/testdata/expressions.golden
@@ -94,30 +94,49 @@ func _() {
 	_ = under_bar - 1
 	_ = Open(dpath+"/file", O_WRONLY|O_CREAT, 0666)
 	_ = int(c0&_Mask4)<<18 | int(c1&_Maskx)<<12 | int(c2&_Maskx)<<6 | int(c3&_Maskx)
-}
-
 
-func _() {
+	// the parser does not restrict expressions that may appear as statements
+	true
+	42
+	"foo"
+	x
+	(x)
 	a + b
 	a + b + c
-	a + b*c
 	a + (b * c)
-	(a + b) * c
-	a + (b * c * d)
-	a + (b*c + d)
+	a + (b / c)
+	1 + a
+	a + 1
+	s[a]
+	x << 1
+	(s[0] << 1) & 0xf
+	"foo" + s
+	x == y
+	x < y || z > 42
+}
+
+
+func _() {
+	_ = a + b
+	_ = a + b + c
+	_ = a + b*c
+	_ = a + (b * c)
+	_ = (a + b) * c
+	_ = a + (b * c * d)
+	_ = a + (b*c + d)
 
-	1 << x
-	-1 << x
-	1<<x - 1
-	-1<<x - 1
+	_ = 1 << x
+	_ = -1 << x
+	_ = 1<<x - 1
+	_ = -1<<x - 1
 
-	f(a + b)
-	f(a + b + c)
-	f(a + b*c)
-	f(a + (b * c))
-	f(1<<x-1, 1<<x-2)
+	_ = f(a + b)
+	_ = f(a + b + c)
+	_ = f(a + b*c)
+	_ = f(a + (b * c))
+	_ = f(1<<x-1, 1<<x-2)
 
-	1<<d.logWindowSize - 1
+	_ = 1<<d.logWindowSize - 1
 
 	buf = make(x, 2*cap(b.buf)+n)
 
@@ -131,7 +150,7 @@ func _() {
 	signed += ' ' * 8
 	tw.octal(header[148:155], chksum)
 
-	x > 0 && i >= 0
+	_ = x > 0 && i >= 0
 
 	x1, x0 := x>>w2, x&m2
 	z0 = t1<<w2 + t0
@@ -141,31 +160,31 @@ func _() {
 	x1 = (x1 << z) | (x0 >> (uint(w) - z))
 	x1 = x1<<z | x0>>(uint(w)-z)
 
-	buf[0 : len(buf)+1]
-	buf[0 : n+1]
+	_ = buf[0 : len(buf)+1]
+	_ = buf[0 : n+1]
 
 	a, b = b, a
 	a = b + c
 	a = b*c + d
-	a*b + c
-	a - b - c
-	a - (b - c)
-	a - b*c
-	a - (b * c)
-	a * b / c
-	a / *b
-	x[a|^b]
-	x[a / *b]
-	a & ^b
-	a + +b
-	a - -b
-	x[a*-b]
-	x[a + +b]
-	x ^ y ^ z
-	b[a>>24] ^ b[(a>>16)&0xFF] ^ b[(a>>8)&0xFF] ^ b[a&0xFF]
-	len(longVariableName) * 2
-
-	token(matchType + xlength<<lengthShift + xoffset)
+	_ = a*b + c
+	_ = a - b - c
+	_ = a - (b - c)
+	_ = a - b*c
+	_ = a - (b * c)
+	_ = a * b / c
+	_ = a / *b
+	_ = x[a|^b]
+	_ = x[a / *b]
+	_ = a & ^b
+	_ = a + +b
+	_ = a - -b
+	_ = x[a*-b]
+	_ = x[a + +b]
+	_ = x ^ y ^ z
+	_ = b[a>>24] ^ b[(a>>16)&0xFF] ^ b[(a>>8)&0xFF] ^ b[a&0xFF]
+	_ = len(longVariableName) * 2
+
+	_ = token(matchType + xlength<<lengthShift + xoffset)
 }
 
 
diff --git a/src/pkg/go/printer/testdata/expressions.input b/src/pkg/go/printer/testdata/expressions.input
index b87381198..d11314983 100644
--- a/src/pkg/go/printer/testdata/expressions.input
+++ b/src/pkg/go/printer/testdata/expressions.input
@@ -94,30 +94,49 @@ func _() {
 	_ = under_bar-1
 	_ = Open(dpath + "/file", O_WRONLY | O_CREAT, 0666)
 	_ = int(c0&_Mask4)<<18 | int(c1&_Maskx)<<12 | int(c2&_Maskx)<<6 | int(c3&_Maskx)
-}
-
 
-func _() {
+	// the parser does not restrict expressions that may appear as statements
+	true
+	42
+	"foo"
+	x
+	(x)
 	a+b
 	a+b+c
-	a+b*c
 	a+(b*c)
-	(a+b)*c
-	a+(b*c*d)
-	a+(b*c+d)
+	a+(b/c)
+	1+a
+	a+1
+	s[a]
+	x<<1
+	(s[0]<<1)&0xf
+	"foo"+s
+	x == y
+	x < y || z > 42
+}
 
-	1<<x
-	-1<<x
-	1<<x-1
-	-1<<x-1
 
-	f(a+b)
-	f(a+b+c)
-	f(a+b*c)
-	f(a+(b*c))
-	f(1<<x-1, 1<<x-2)
+func _() {
+	_ = a+b
+	_ = a+b+c
+	_ = a+b*c
+	_ = a+(b*c)
+	_ = (a+b)*c
+	_ = a+(b*c*d)
+	_ = a+(b*c+d)
+
+	_ = 1<<x
+	_ = -1<<x
+	_ = 1<<x-1
+	_ = -1<<x-1
 
-	1<<d.logWindowSize-1
+	_ = f(a+b)
+	_ = f(a+b+c)
+	_ = f(a+b*c)
+	_ = f(a+(b*c))
+	_ = f(1<<x-1, 1<<x-2)
+
+	_ = 1<<d.logWindowSize-1
 
 	buf = make(x, 2*cap(b.buf) + n)
 
@@ -131,7 +150,7 @@ func _() {
 	signed += ' '*8
 	tw.octal(header[148:155], chksum)
 
-	x > 0 && i >= 0
+	_ = x > 0 && i >= 0
 
 	x1, x0 := x>>w2, x&m2
 	z0 = t1<<w2+t0
@@ -141,31 +160,31 @@ func _() {
 	x1 = (x1<<z)|(x0>>(uint(w)-z))
 	x1 = x1<<z | x0>>(uint(w)-z)
 
-	buf[0:len(buf)+1]
-	buf[0:n+1]
+	_ = buf[0:len(buf)+1]
+	_ = buf[0:n+1]
 
 	a,b = b,a
 	a = b+c
 	a = b*c+d
-	a*b+c
-	a-b-c
-	a-(b-c)
-	a-b*c
-	a-(b*c)
-	a*b/c
-	a/ *b
-	x[a|^b]
-	x[a/ *b]
-	a& ^b
-	a+ +b
-	a- -b
-	x[a*-b]
-	x[a+ +b]
-	x^y^z
-	b[a>>24] ^ b[(a>>16)&0xFF] ^ b[(a>>8)&0xFF] ^ b[a&0xFF]
-	len(longVariableName)*2
-
-	token(matchType + xlength<<lengthShift + xoffset)
+	_ = a*b+c
+	_ = a-b-c
+	_ = a-(b-c)
+	_ = a-b*c
+	_ = a-(b*c)
+	_ = a*b/c
+	_ = a/ *b
+	_ = x[a|^b]
+	_ = x[a/ *b]
+	_ = a& ^b
+	_ = a+ +b
+	_ = a- -b
+	_ = x[a*-b]
+	_ = x[a+ +b]
+	_ = x^y^z
+	_ = b[a>>24] ^ b[(a>>16)&0xFF] ^ b[(a>>8)&0xFF] ^ b[a&0xFF]
+	_ = len(longVariableName)*2
+
+	_ = token(matchType + xlength<<lengthShift + xoffset)
 }
 
 
diff --git a/src/pkg/go/printer/testdata/expressions.raw b/src/pkg/go/printer/testdata/expressions.raw
index 735cd943e..72ab850fa 100644
--- a/src/pkg/go/printer/testdata/expressions.raw
+++ b/src/pkg/go/printer/testdata/expressions.raw
@@ -94,30 +94,49 @@ func _() {
 	_ = under_bar - 1
 	_ = Open(dpath+"/file", O_WRONLY|O_CREAT, 0666)
 	_ = int(c0&_Mask4)<<18 | int(c1&_Maskx)<<12 | int(c2&_Maskx)<<6 | int(c3&_Maskx)
-}
-
 
-func _() {
+	// the parser does not restrict expressions that may appear as statements
+	true
+	42
+	"foo"
+	x
+	(x)
 	a + b
 	a + b + c
-	a + b*c
 	a + (b * c)
-	(a + b) * c
-	a + (b * c * d)
-	a + (b*c + d)
+	a + (b / c)
+	1 + a
+	a + 1
+	s[a]
+	x << 1
+	(s[0] << 1) & 0xf
+	"foo" + s
+	x == y
+	x < y || z > 42
+}
+
+
+func _() {
+	_ = a + b
+	_ = a + b + c
+	_ = a + b*c
+	_ = a + (b * c)
+	_ = (a + b) * c
+	_ = a + (b * c * d)
+	_ = a + (b*c + d)
 
-	1 << x
-	-1 << x
-	1<<x - 1
-	-1<<x - 1
+	_ = 1 << x
+	_ = -1 << x
+	_ = 1<<x - 1
+	_ = -1<<x - 1
 
-	f(a + b)
-	f(a + b + c)
-	f(a + b*c)
-	f(a + (b * c))
-	f(1<<x-1, 1<<x-2)
+	_ = f(a + b)
+	_ = f(a + b + c)
+	_ = f(a + b*c)
+	_ = f(a + (b * c))
+	_ = f(1<<x-1, 1<<x-2)
 
-	1<<d.logWindowSize - 1
+	_ = 1<<d.logWindowSize - 1
 
 	buf = make(x, 2*cap(b.buf)+n)
 
@@ -131,7 +150,7 @@ func _() {
 	signed += ' ' * 8
 	tw.octal(header[148:155], chksum)
 
-	x > 0 && i >= 0
+	_ = x > 0 && i >= 0
 
 	x1, x0 := x>>w2, x&m2
 	z0 = t1<<w2 + t0
@@ -141,31 +160,31 @@ func _() {
 	x1 = (x1 << z) | (x0 >> (uint(w) - z))
 	x1 = x1<<z | x0>>(uint(w)-z)
 
-	buf[0 : len(buf)+1]
-	buf[0 : n+1]
+	_ = buf[0 : len(buf)+1]
+	_ = buf[0 : n+1]
 
 	a, b = b, a
 	a = b + c
 	a = b*c + d
-	a*b + c
-	a - b - c
-	a - (b - c)
-	a - b*c
-	a - (b * c)
-	a * b / c
-	a / *b
-	x[a|^b]
-	x[a / *b]
-	a & ^b
-	a + +b
-	a - -b
-	x[a*-b]
-	x[a + +b]
-	x ^ y ^ z
-	b[a>>24] ^ b[(a>>16)&0xFF] ^ b[(a>>8)&0xFF] ^ b[a&0xFF]
-	len(longVariableName) * 2
-
-	token(matchType + xlength<<lengthShift + xoffset)
+	_ = a*b + c
+	_ = a - b - c
+	_ = a - (b - c)
+	_ = a - b*c
+	_ = a - (b * c)
+	_ = a * b / c
+	_ = a / *b
+	_ = x[a|^b]
+	_ = x[a / *b]
+	_ = a & ^b
+	_ = a + +b
+	_ = a - -b
+	_ = x[a*-b]
+	_ = x[a + +b]
+	_ = x ^ y ^ z
+	_ = b[a>>24] ^ b[(a>>16)&0xFF] ^ b[(a>>8)&0xFF] ^ b[a&0xFF]
+	_ = len(longVariableName) * 2
+
+	_ = token(matchType + xlength<<lengthShift + xoffset)
 }