cmd/compile/internal/types2: simplify error reporting API (cleanup)

- Remove specialized errorf functions for invalid AST/argument/operation.
  Instead use prefix constants with the error message.

- Replace several calls to Checker.errorf with calls to Checker.error
  if there are no arguments to format.

- Replace a handful of %s format verbs with %v to satisfy vet check.

- Add a basic test that checks that we're not using Checker.errorf when
  we should be using Checker.error.

Change-Id: I7bc7c14f3cf774689ec8cd5782ea31b6e30dbcd6
Reviewed-on: https://go-review.googlesource.com/c/go/+/300995
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/cmd/compile/internal/types2/assignments.go b/src/cmd/compile/internal/types2/assignments.go
index 00495f3976..18ae0ddf62 100644
--- a/src/cmd/compile/internal/types2/assignments.go
+++ b/src/cmd/compile/internal/types2/assignments.go
@@ -194,7 +194,7 @@ func (check *Checker) assignVar(lhs syntax.Expr, x *operand) Type {
 	case variable, mapindex:
 		// ok
 	case nilvalue:
-		check.errorf(&z, "cannot assign to nil") // default would print "untyped nil"
+		check.error(&z, "cannot assign to nil") // default would print "untyped nil"
 		return nil
 	default:
 		if sel, ok := z.expr.(*syntax.SelectorExpr); ok {