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, 2 insertions, 2 deletions

diff --git a/src/cmd/compile/internal/types2/call.go b/src/cmd/compile/internal/types2/call.go
index 320e12d4d6..93f4c51937 100644
--- a/src/cmd/compile/internal/types2/call.go
+++ b/src/cmd/compile/internal/types2/call.go
@@ -158,7 +158,7 @@ func (check *Checker) call(x *operand, call *syntax.CallExpr) exprKind {
 
 		sig := asSignature(x.typ)
 		if sig == nil {
-			check.invalidOpf(x, "cannot call non-function %s", x)
+			check.errorf(x, invalidOp+"cannot call non-function %s", x)
 			x.mode = invalid
 			x.expr = call
 			return statement
@@ -248,7 +248,7 @@ func (check *Checker) exprOrTypeList(elist []syntax.Expr) (xlist []*operand, ok
 			}
 		}
 		if 0 < ntypes && ntypes < len(xlist) {
-			check.errorf(xlist[0], "mix of value and type expressions")
+			check.error(xlist[0], "mix of value and type expressions")
 			ok = false
 		}
 	}