cmd/gofmt: normalize integer imaginary literals starting with 0
An 'i' suffix on an integer literal marks the integer literal as
a decimal integer imaginary value, even if the literal without the
suffix starts with a 0 and thus looks like an octal value:
0123i == 123i // != 0123 * 1i
This is at best confusing, and at worst a potential source of bugs.
It is always safe to rewrite such literals into the equivalent
literal without the leading 0.
This CL implements this normalization.
Change-Id: Ib77ad535f98b5be912ecbdec20ca1b472c1b4973
Reviewed-on: https://go-review.googlesource.com/c/162538
Run-TryBot: Robert Griesemer <gri@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/src/cmd/gofmt/gofmt.go b/src/cmd/gofmt/gofmt.go
index ce4613f..4bba444 100644
--- a/src/cmd/gofmt/gofmt.go
+++ b/src/cmd/gofmt/gofmt.go
@@ -330,7 +330,9 @@
}
// normalizeNumbers rewrites base prefixes and exponents to
-// use lower-case letters. It leaves hexadecimal digits alone.
+// use lower-case letters, and removes leading 0's from
+// integer imaginary literals. It leaves hexadecimal digits
+// alone.
func normalizeNumbers(n ast.Node) bool {
lit, _ := n.(*ast.BasicLit)
if lit == nil {
@@ -339,37 +341,60 @@
if len(lit.Value) < 2 {
return false // only one digit - nothing to do
}
- // lit.Value >= 2
+ // len(lit.Value) >= 2
+ x := lit.Value
switch lit.Kind {
case token.INT:
- switch lit.Value[:2] {
+ switch x[:2] {
case "0X":
- lit.Value = "0x" + lit.Value[2:]
+ lit.Value = "0x" + x[2:]
case "0O":
- lit.Value = "0o" + lit.Value[2:]
+ lit.Value = "0o" + x[2:]
case "0B":
- lit.Value = "0b" + lit.Value[2:]
+ lit.Value = "0b" + x[2:]
}
case token.FLOAT:
switch lit.Value[:2] {
default:
- if i := strings.LastIndexByte(lit.Value, 'E'); i >= 0 {
- lit.Value = lit.Value[:i] + "e" + lit.Value[i+1:]
+ if i := strings.LastIndexByte(x, 'E'); i >= 0 {
+ lit.Value = x[:i] + "e" + x[i+1:]
}
case "0x":
- if i := strings.LastIndexByte(lit.Value, 'P'); i >= 0 {
- lit.Value = lit.Value[:i] + "p" + lit.Value[i+1:]
+ if i := strings.LastIndexByte(x, 'P'); i >= 0 {
+ lit.Value = x[:i] + "p" + x[i+1:]
}
case "0X":
- if i := strings.LastIndexByte(lit.Value, 'P'); i >= 0 {
- lit.Value = "0x" + lit.Value[2:i] + "p" + lit.Value[i+1:]
+ if i := strings.LastIndexByte(x, 'P'); i >= 0 {
+ lit.Value = "0x" + x[2:i] + "p" + x[i+1:]
} else {
- lit.Value = "0x" + lit.Value[2:]
+ lit.Value = "0x" + x[2:]
}
}
+
+ case token.IMAG:
+ // Note that integer imaginary literals may contain
+ // any decimal digit even if they start with zero.
+ // Imaginary literals should always end in 'i' but be
+ // conservative and check anyway before proceeding.
+ if x[0] == '0' && x[len(x)-1] == 'i' && isDecimals(x[1:len(x)-1]) {
+ x = strings.TrimLeft(x, "0_")
+ if x == "i" {
+ x = "0i"
+ }
+ lit.Value = x
+ }
}
return false
}
+
+// isDecimals reports whether x consists entirely of decimal digits and underscores.
+func isDecimals(x string) bool {
+ i := 0
+ for i < len(x) && ('0' <= x[i] && x[i] <= '9' || x[i] == '_') {
+ i++
+ }
+ return i == len(x)
+}
diff --git a/src/cmd/gofmt/testdata/go2numbers.golden b/src/cmd/gofmt/testdata/go2numbers.golden
index 2fab834..abefcb6 100644
--- a/src/cmd/gofmt/testdata/go2numbers.golden
+++ b/src/cmd/gofmt/testdata/go2numbers.golden
@@ -141,10 +141,22 @@
// imaginaries
_ = 0i
- _ = 00i
+ _ = 0i
+ _ = 8i
+ _ = 0i
+ _ = 123i
+ _ = 123i
+ _ = 56789i
_ = 1234i
_ = 1234567i
+ _ = 0i
+ _ = 0i
+ _ = 8i
+ _ = 0i
+ _ = 123i
+ _ = 123i
+ _ = 56_789i
_ = 1_234i
_ = 1_234_567i
diff --git a/src/cmd/gofmt/testdata/go2numbers.input b/src/cmd/gofmt/testdata/go2numbers.input
index 7b3fd39..51a9f8e 100644
--- a/src/cmd/gofmt/testdata/go2numbers.input
+++ b/src/cmd/gofmt/testdata/go2numbers.input
@@ -142,9 +142,21 @@
// imaginaries
_ = 0i
_ = 00i
+ _ = 08i
+ _ = 0000000000i
+ _ = 0123i
+ _ = 0000000123i
+ _ = 0000056789i
_ = 1234i
_ = 1234567i
+ _ = 0i
+ _ = 0_0i
+ _ = 0_8i
+ _ = 0_000_000_000i
+ _ = 0_123i
+ _ = 0_000_000_123i
+ _ = 0_000_056_789i
_ = 1_234i
_ = 1_234_567i
