fix(compiler): Fix validation of GROUP BY on field aliases

internal/compiler/output_columns.go

@@ -72,7 +72,7 @@ func outputColumns(qc *QueryCatalog, node ast.Node) ([]*Column, error) {
 					continue
 				}
 
-				if err := findColumnForRef(ref, tables); err != nil {
+				if err := findColumnForRef(ref, tables, n); err != nil {
 					return nil, err
 				}
 			}
@@ -485,7 +485,7 @@ func outputColumnRefs(res *ast.ResTarget, tables []*Table, node *ast.ColumnRef)
 	return cols, nil
 }
 
-func findColumnForRef(ref *ast.ColumnRef, tables []*Table) error {
+func findColumnForRef(ref *ast.ColumnRef, tables []*Table, selectStatement *ast.SelectStmt) error {
 	parts := stringSlice(ref.Fields)
 	var alias, name string
 	if len(parts) == 1 {
@@ -500,9 +500,28 @@ func findColumnForRef(ref *ast.ColumnRef, tables []*Table) error {
 		if alias != "" && t.Rel.Name != alias {
 			continue
 		}
+
+		// Find matching column
+		var foundColumn bool
 		for _, c := range t.Columns {
 			if c.Name == name {
 				found++
+				foundColumn = true
+			}
+		}
+
+		if foundColumn {
+			continue
+		}
+
+		// Find matching alias
+		for _, c := range selectStatement.TargetList.Items {
+			resTarget, ok := c.(*ast.ResTarget)
+			if !ok {
+				continue
+			}
+			if resTarget.Name != nil && *resTarget.Name == name {
+				found++
 			}
 		}
 	}

internal/endtoend/testdata/valid_group_by_reference/mysql/query.sql

@@ -0,0 +1,47 @@
+CREATE TABLE authors (
+  id   BIGINT  NOT NULL AUTO_INCREMENT PRIMARY KEY,
+  name text    NOT NULL,
+  bio  text,
+  UNIQUE(name)
+);
+
+-- name: ListAuthors :many
+SELECT   id, name as full_name, bio
+FROM     authors
+GROUP BY full_name;
+
+-- name: ListAuthorsIdenticalAlias :many
+SELECT   id, name as name, bio
+FROM     authors
+GROUP BY name;
+
+
+-- https://github.com/kyleconroy/sqlc/issues/1315
+
+CREATE TABLE IF NOT EXISTS weather_metrics
+(
+    time             TIMESTAMP NOT NULL,
+    timezone_shift   INT       NULL,
+    city_name        TEXT      NULL,
+    temp_c           FLOAT     NULL,
+    feels_like_c     FLOAT     NULL,
+    temp_min_c       FLOAT     NULL,
+    temp_max_c       FLOAT     NULL,
+    pressure_hpa     FLOAT     NULL,
+    humidity_percent FLOAT     NULL,
+    wind_speed_ms    FLOAT     NULL,
+    wind_deg         INT       NULL,
+    rain_1h_mm       FLOAT     NULL,
+    rain_3h_mm       FLOAT     NULL,
+    snow_1h_mm       FLOAT     NULL,
+    snow_3h_mm       FLOAT     NULL,
+    clouds_percent   INT       NULL,
+    weather_type_id  INT       NULL
+);
+
+-- name: ListMetrics :many
+SELECT time_bucket('15 days', time) AS bucket, city_name, AVG(temp_c)
+FROM weather_metrics
+WHERE DATE_SUB(NOW(), INTERVAL 6 MONTH)
+GROUP BY bucket, city_name
+ORDER BY bucket DESC;

internal/endtoend/testdata/valid_group_by_reference/mysql/sqlc.json

@@ -0,0 +1,12 @@
+{
+	"version": "1",
+	"packages": [
+		{
+			"path": "go",
+			"engine": "mysql",
+			"name": "querytest",
+			"schema": "query.sql",
+			"queries": "query.sql"
+		}
+	]
+}