[dev.typeparams] cmd/compile/internal/types2: cleanup panic calls

End-users are not expected to deal with the details of panics,
so providing extra information such as an "internal error" prefix
or the name of the function invoking the panic are not helpful.

Remove unnecessary panic verbiage if it is readily available from
a stack trace (such as the function where it happens, and the fact
that is is an "internal error").

Change-Id: I5f86bae6d2cca7c04ce692d17257da7ddee206d7
Reviewed-on: https://go-review.googlesource.com/c/go/+/339969
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/cmd/compile/internal/types2/typestring.go b/src/cmd/compile/internal/types2/typestring.go
index 628eeaf3dd..b3675424a5 100644
--- a/src/cmd/compile/internal/types2/typestring.go
+++ b/src/cmd/compile/internal/types2/typestring.go
@@ -130,7 +130,7 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 		// Unions only appear as (syntactic) embedded elements
 		// in interfaces and syntactically cannot be empty.
 		if t.NumTerms() == 0 {
-			panic("internal error: empty union")
+			panic("empty union")
 		}
 		for i, t := range t.terms {
 			if i > 0 {
@@ -183,7 +183,7 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 		case RecvOnly:
 			s = "<-chan "
 		default:
-			panic("unreachable")
+			unreachable()
 		}
 		buf.WriteString(s)
 		if parens {
@@ -329,7 +329,7 @@ func writeTuple(buf *bytes.Buffer, tup *Tuple, variadic bool, qf Qualifier, visi
 					// special case:
 					// append(s, "foo"...) leads to signature func([]byte, string...)
 					if t := asBasic(typ); t == nil || t.kind != String {
-						panic("internal error: string type expected")
+						panic("expected string type")
 					}
 					writeType(buf, typ, qf, visited)
 					buf.WriteString("...")