fmt: fix incorrect format of whole-number floats when using %#v

This fixes the unwanted behaviour where printing a zero float with the
#v fmt verb outputs "0" - e.g. missing the trailing decimal. This means
that the output would be interpreted as an int rather than a float when
parsed as Go source. After this change the the output is "0.0".

Fixes #26363

Change-Id: Ic5c060522459cd5ce077675d47c848b22ddc34fa
GitHub-Last-Rev: adfb061363f0566acec134c81be9a3dcb1f4cac8
GitHub-Pull-Request: golang/go#26383
Reviewed-on: https://go-review.googlesource.com/123956
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Rob Pike <r@golang.org>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/test/switch5.go b/test/switch5.go
index ce95bf8d7b..6641d582bc 100644
--- a/test/switch5.go
+++ b/test/switch5.go
@@ -24,8 +24,8 @@ func f0(x int) {
 func f1(x float32) {
 	switch x {
 	case 5:
-	case 5: // ERROR "duplicate case 5 in switch"
-	case 5.0: // ERROR "duplicate case 5 in switch"
+	case 5: // ERROR "duplicate case 5 .value 5\.0. in switch"
+	case 5.0: // ERROR "duplicate case 5 .value 5\.0. in switch"
 	}
 }
 
@@ -44,9 +44,9 @@ func f3(e interface{}) {
 	case 0: // ERROR "duplicate case 0 in switch"
 	case int64(0):
 	case float32(10):
-	case float32(10): // ERROR "duplicate case float32\(10\) .value 10. in switch"
+	case float32(10): // ERROR "duplicate case float32\(10\) .value 10\.0. in switch"
 	case float64(10):
-	case float64(10): // ERROR "duplicate case float64\(10\) .value 10. in switch"
+	case float64(10): // ERROR "duplicate case float64\(10\) .value 10\.0. in switch"
 	}
 }