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

Numbers without decimals are valid Go representations of whole-number
floats. That is, "var x float64 = 5" is valid Go. Avoid breakage in
tests that expect a certain output from %#v by reverting to it.

To guarantee the right type is generated by a print use %T(%#v) instead.

Added a test to lock in this behavior.

This reverts commit 7c7cecc1846aaaa0ce73931644fe1df2b4559e09.

Fixes #27634
Updates #26363

Change-Id: I544c400a0903777dd216452a7e86dfe60b0b0283
Reviewed-on: https://go-review.googlesource.com/c/142597
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/test/switch5.go b/test/switch5.go
index 6641d582bc..ce95bf8d7b 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 .value 5\.0. in switch"
-	case 5.0: // ERROR "duplicate case 5 .value 5\.0. in switch"
+	case 5: // ERROR "duplicate case 5 in switch"
+	case 5.0: // ERROR "duplicate case 5 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\.0. in switch"
+	case float32(10): // ERROR "duplicate case float32\(10\) .value 10. in switch"
 	case float64(10):
-	case float64(10): // ERROR "duplicate case float64\(10\) .value 10\.0. in switch"
+	case float64(10): // ERROR "duplicate case float64\(10\) .value 10. in switch"
 	}
 }