From 844ce4731ef72ce805b0f8e211bd555f919fcdfa Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Tue, 25 Jun 2019 20:24:17 +0300
Subject: [PATCH] app/vmselect/promql: suppress error when template func is
 used inside modifier list. Just leave it as is

Fixes https://github.com/VictoriaMetrics/VictoriaMetrics/issues/78
---
 app/vmselect/promql/parser.go      | 16 +++++++++++++++-
 app/vmselect/promql/parser_test.go | 12 +++++++++---
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/app/vmselect/promql/parser.go b/app/vmselect/promql/parser.go
index fddfd8c69..6c72690d0 100644
--- a/app/vmselect/promql/parser.go
+++ b/app/vmselect/promql/parser.go
@@ -811,7 +811,9 @@ func expandModifierArgs(was []*withArgExpr, args []string) ([]string, error) {
 			continue
 		}
 		if len(wa.Args) > 0 {
-			return nil, fmt.Errorf("cannot use func %q instead of %q in %s", wa.Name, arg, args)
+			// Template funcs cannot be used inside modifier list. Leave the arg as is.
+			dstArgs = append(dstArgs, arg)
+			continue
 		}
 		me, ok := wa.Expr.(*metricExpr)
 		if ok {
@@ -851,6 +853,10 @@ func expandModifierArgs(was []*withArgExpr, args []string) ([]string, error) {
 
 func expandWithExprExt(was []*withArgExpr, wa *withArgExpr, args []expr) (expr, error) {
 	if len(wa.Args) != len(args) {
+		if args == nil {
+			// Just return metricExpr with the wa.Name name.
+			return newMetricExpr(wa.Name), nil
+		}
 		return nil, fmt.Errorf("invalid number of args for %q; got %d; want %d", wa.Name, len(args), len(wa.Args))
 	}
 	wasNew := make([]*withArgExpr, 0, len(was)+len(args))
@@ -869,6 +875,14 @@ func expandWithExprExt(was []*withArgExpr, wa *withArgExpr, args []expr) (expr,
 	return expandWithExpr(wasNew, wa.Expr)
 }
 
+func newMetricExpr(name string) *metricExpr {
+	return &metricExpr{
+		TagFilters: []storage.TagFilter{{
+			Value: []byte(name),
+		}},
+	}
+}
+
 func extractStringValue(token string) (string, error) {
 	if !isStringPrefix(token) {
 		return "", fmt.Errorf(`stringExpr must contain only string literals; got %q`, token)
diff --git a/app/vmselect/promql/parser_test.go b/app/vmselect/promql/parser_test.go
index 8f4d35089..cc90abf19 100644
--- a/app/vmselect/promql/parser_test.go
+++ b/app/vmselect/promql/parser_test.go
@@ -118,6 +118,10 @@ func TestParsePromQLSuccess(t *testing.T) {
 	same("with")
 	same("WITH")
 	same("With")
+	same("alias")
+	same(`alias{foo="bar"}`)
+	same(`aLIas{alias="aa"}`)
+	another(`al\ias`, `alias`)
 	// identifiers with with escape chars
 	same(`foo\ bar`)
 	same(`foo\-bar\{{baz\+bar="aa"}`)
@@ -345,8 +349,11 @@ func TestParsePromQLSuccess(t *testing.T) {
 	another(`with (x="a", y=x) y+"bc"`, `"abc"`)
 	another(`with (x="a", y="b"+x) "we"+y+"z"+f()`, `"webaz" + f()`)
 	another(`with (f(x) = m{foo=x+"y", bar="y"+x, baz=x} + x) f("qwe")`, `m{foo="qwey", bar="yqwe", baz="qwe"} + "qwe"`)
+	another(`with (f(a)=a) f`, `f`)
+	another(`with (f\q(a)=a) f\q`, `fq`)
 
 	// Verify withExpr for aggr func modifiers
+	another(`with (f(x) = x, y = sum(m) by (f)) y`, `sum(m) by (f)`)
 	another(`with (f(x) = sum(m) by (x)) f(foo)`, `sum(m) by (foo)`)
 	another(`with (f(x) = sum(m) by (x)) f((foo, bar, foo))`, `sum(m) by (foo, bar)`)
 	another(`with (f(x) = sum(m) without (x,y)) f((a, b))`, `sum(m) without (a, b, y)`)
@@ -671,7 +678,7 @@ func TestParsePromQLError(t *testing.T) {
 	f(`with (x=m) f(b, a{x})`)
 	f(`with (x=m) sum(a{x})`)
 	f(`with (x=m) (a{x})`)
-	f(`with (f(a)=a) f`)
+	f(`with (f(a)=a) f(1, 2)`)
 	f(`with (f(x)=x{foo="bar"}) f(1)`)
 	f(`with (f(x)=x{foo="bar"}) f(m + n)`)
 	f(`with (f = with`)
@@ -681,8 +688,7 @@ func TestParsePromQLError(t *testing.T) {
 	f(`with (f(,)=x) x`)
 	f(`with (x(a) = {b="c"}) foo{x}`)
 	f(`with (f(x) = m{foo=xx}) f("qwe")`)
-	f(`a + with(f(x)=x) f`)
-	f(`with (f(x) = x, y = sum(m) by (f)) y`)
+	f(`a + with(f(x)=x) f(1,2)`)
 	f(`with (f(x) = sum(m) by (x)) f({foo="bar"})`)
 	f(`with (f(x) = sum(m) by (x)) f((xx(), {foo="bar"}))`)
 	f(`with (f(x) = m + on (x) n) f(xx())`)