Makefile: run gocritic with -enableAll over our sources (#987)

Signed-off-by: Iskander Sharipov <quasilyte@gmail.com>

Makefile

@@ -36,6 +36,8 @@ ci-linter:
 	@$(GOPATH_DIR)/bin/golangci-lint run -v
 	go install github.com/quasilyte/go-consistent
 	@$(GOPATH_DIR)/bin/go-consistent ./...
+	go build -o gocritic ./cmd/gocritic
+	./gocritic check -enableAll ./...
 
 cover:
 	go install github.com/mattn/goveralls

checkers/sortSlice_checker.go

@@ -87,7 +87,7 @@ func (c *sortSliceChecker) VisitExpr(expr ast.Expr) {
 	}
 }
 
-func (c *sortSliceChecker) paramIdents(e *ast.FuncType) (*ast.Ident, *ast.Ident) {
+func (c *sortSliceChecker) paramIdents(e *ast.FuncType) (ivar, jvar *ast.Ident) {
 	// Covers both `i, j int` and `i int, j int`.
 	idents := make([]*ast.Ident, 0, 2)
 	for _, field := range e.Params.List {

checkers/whyNoLint_checker.go

@@ -44,7 +44,7 @@ func (c whyNoLintChecker) VisitComment(cg *ast.CommentGroup) {
 			continue
 		}
 
-		if s := sl[1]; !strings.HasPrefix(s, "//") || len(strings.TrimPrefix(s, "//")) == 0 {
+		if s := sl[1]; !strings.HasPrefix(s, "//") || strings.TrimPrefix(s, "//") == "" {
 			c.ctx.Warn(cg, "include an explanation for nolint directive")
 			return
 		}

rules.go

@@ -1,4 +1,4 @@
-//nolint
+//nolint // it's not a Go code file
 package gorules
 
 import (