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strconv: fix for parseFloatPrefix

parseFloatPrefix accepts a string if it has a valid floating-point
number as prefix. Make sure that "infi", "infin", ... etc. are
accepted as valid numbers "inf" with suffix "i", "in", etc. This
is important for parsing complex numbers such as "0+infi".

This change does not affect the correctness of ParseFloat because
ParseFloat rejects strings that contain a suffix after a valid
floating-point number.

Updates #36771.

Change-Id: Ie1693a8ca2f8edf07b57688e0b35751b7100d39d
Reviewed-on: https://go-review.googlesource.com/c/go/+/231237
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Robert Griesemer 2020-04-30 13:24:05 -07:00
parent 0f8fecaba7
commit 8740bdc5af
2 changed files with 8 additions and 3 deletions

View File

@ -55,7 +55,11 @@ func special(s string) (f float64, n int, ok bool) {
fallthrough
case 'i', 'I':
n := commonPrefixLenIgnoreCase(s, "infinity")
// both "inf" and "infinity" are ok
// Anything longer than "inf" is ok, but if we
// don't have "infinity", only consume "inf".
if 3 < n && n < 8 {
n = 3
}
if n == 3 || n == 8 {
return math.Inf(sign), nsign + n, true
}

View File

@ -486,8 +486,9 @@ func TestParseFloatPrefix(t *testing.T) {
continue
}
// Adding characters that do not extend a number should not invalidate it.
// Test a few.
for _, suffix := range []string{" ", "q", "+", "-", "<", "=", ">", "(", ")"} {
// Test a few. The "i" and "init" cases test that we accept "infi", "infinit"
// correctly as "inf" with suffix.
for _, suffix := range []string{" ", "q", "+", "-", "<", "=", ">", "(", ")", "i", "init"} {
in := test.in + suffix
_, n, err := ParseFloatPrefix(in, 64)
if err != nil {