fix(compiler): reject sqlc.embed on the nullable side of an outer join

internal/compiler/output_columns.go

@@ -9,6 +9,7 @@ import (
 	"github.com/sqlc-dev/sqlc/internal/sql/astutils"
 	"github.com/sqlc-dev/sqlc/internal/sql/catalog"
 	"github.com/sqlc-dev/sqlc/internal/sql/lang"
+	"github.com/sqlc-dev/sqlc/internal/sql/preprocess"
 	"github.com/sqlc-dev/sqlc/internal/sql/sqlerr"
 )
 
@@ -53,6 +54,8 @@ func hasStarRef(cf *ast.ColumnRef) bool {
 // Return an error if column references are ambiguous
 // Return an error if column references don't exist
 func (c *Compiler) outputColumns(qc *QueryCatalog, node ast.Node) ([]*Column, error) {
+	var embedErr error
+
 	tables, err := c.sourceTables(qc, node)
 	if err != nil {
 		return nil, err
@@ -267,6 +270,11 @@ func (c *Compiler) outputColumns(qc *QueryCatalog, node ast.Node) ([]*Column, er
 
 				// add a column with a reference to an embedded table
 				if embed, ok := qc.embeds.Find(n.Location, res.Location); ok {
+					// Keep the column and report the error with the rest, so an
+					// analyzer that discards inference errors still sees the embed.
+					if err := checkEmbedRequired(node, embed, res.Location); err != nil && embedErr == nil {
+						embedErr = err
+					}
 					cols = append(cols, &Column{
 						Name:       embed.Table.Name,
 						EmbedTable: embed.Table,
@@ -416,7 +424,7 @@ func (c *Compiler) outputColumns(qc *QueryCatalog, node ast.Node) ([]*Column, er
 		}
 	}
 
-	return cols, nil
+	return cols, embedErr
 }
 
 const (
@@ -467,6 +475,31 @@ func isTableRequired(n ast.Node, col *Column, prior int) int {
 	return tableNotFound
 }
 
+// An embedded struct is the model of its table, whose columns may not be
+// nullable, so it cannot hold the NULLs the optional side of an outer join
+// produces.
+func checkEmbedRequired(node ast.Node, embed *preprocess.Embed, location int) error {
+	n, ok := node.(*ast.SelectStmt)
+	if !ok {
+		return nil
+	}
+	col := &Column{Table: embed.Table, TableAlias: embed.Param()}
+	for _, f := range n.FromClause.Items {
+		res := isTableRequired(f, col, tableRequired)
+		if res != tableNotFound {
+			if res == tableOptional {
+				return &sqlerr.Error{
+					Code:     "0A000",
+					Message:  fmt.Sprintf("sqlc.embed(%s) on the nullable side of an outer join is not supported", embed.Param()),
+					Location: location,
+				}
+			}
+			break
+		}
+	}
+	return nil
+}
+
 type tableVisitor struct {
 	list ast.List
 }

internal/endtoend/testdata/sqlc_embed_outer_join_left/postgresql/exec.json

@@ -0,0 +1,3 @@
+{
+    "contexts": ["base"]
+}

internal/endtoend/testdata/sqlc_embed_outer_join_left/postgresql/query.sql

@@ -0,0 +1,3 @@
+-- name: LeftJoin :many
+SELECT sqlc.embed(posts), sqlc.embed(users) FROM posts
+LEFT JOIN users ON posts.user_id = users.id;

internal/endtoend/testdata/sqlc_embed_outer_join_left/postgresql/schema.sql

@@ -0,0 +1,9 @@
+CREATE TABLE users (
+    id integer PRIMARY KEY,
+    name text NOT NULL
+);
+
+CREATE TABLE posts (
+    id integer PRIMARY KEY,
+    user_id integer
+);

internal/endtoend/testdata/sqlc_embed_outer_join_left/postgresql/sqlc.json

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

internal/endtoend/testdata/sqlc_embed_outer_join_left/postgresql/stderr.txt

@@ -0,0 +1,2 @@
+# package querytest
+query.sql:2:27: sqlc.embed(users) on the nullable side of an outer join is not supported

internal/endtoend/testdata/sqlc_embed_outer_join_left/sqlite/exec.json

@@ -0,0 +1,3 @@
+{
+    "contexts": ["base"]
+}

internal/endtoend/testdata/sqlc_embed_outer_join_left/sqlite/query.sql

@@ -0,0 +1,3 @@
+-- name: LeftJoin :many
+SELECT sqlc.embed(p), sqlc.embed(u) FROM posts AS p
+LEFT JOIN users AS u ON p.user_id = u.id;

internal/endtoend/testdata/sqlc_embed_outer_join_left/sqlite/schema.sql

@@ -0,0 +1,9 @@
+CREATE TABLE users (
+    id integer PRIMARY KEY,
+    name text NOT NULL
+);
+
+CREATE TABLE posts (
+    id integer PRIMARY KEY,
+    user_id integer
+);

internal/endtoend/testdata/sqlc_embed_outer_join_left/sqlite/sqlc.json

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

internal/endtoend/testdata/sqlc_embed_outer_join_left/sqlite/stderr.txt

@@ -0,0 +1,2 @@
+# package querytest
+query.sql:2:23: sqlc.embed(u) on the nullable side of an outer join is not supported

internal/endtoend/testdata/sqlc_embed_outer_join_ok/sqlite/query.sql

@@ -0,0 +1,15 @@
+-- name: LeftSideOfLeftJoin :many
+SELECT sqlc.embed(p), u.name FROM posts AS p
+LEFT JOIN users AS u ON p.user_id = u.id;
+
+-- name: RightSideOfRightJoin :many
+SELECT sqlc.embed(u), p.id FROM posts AS p
+RIGHT JOIN users AS u ON p.user_id = u.id;
+
+-- name: InnerJoin :many
+SELECT sqlc.embed(p), sqlc.embed(u) FROM posts AS p
+INNER JOIN users AS u ON p.user_id = u.id;
+
+-- name: SelfJoinRequiredAlias :many
+SELECT sqlc.embed(a), b.name FROM users AS a
+LEFT JOIN users AS b ON a.id = b.id;

internal/endtoend/testdata/sqlc_embed_outer_join_ok/sqlite/schema.sql

@@ -0,0 +1,9 @@
+CREATE TABLE users (
+    id integer PRIMARY KEY,
+    name text NOT NULL
+);
+
+CREATE TABLE posts (
+    id integer PRIMARY KEY,
+    user_id integer
+);

internal/endtoend/testdata/sqlc_embed_outer_join_ok/sqlite/sqlc.json

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

internal/endtoend/testdata/sqlc_embed_outer_join_right/sqlite/exec.json

@@ -0,0 +1,3 @@
+{
+    "contexts": ["base"]
+}

internal/endtoend/testdata/sqlc_embed_outer_join_right/sqlite/query.sql

@@ -0,0 +1,3 @@
+-- name: RightJoin :many
+SELECT sqlc.embed(p), sqlc.embed(u) FROM posts AS p
+RIGHT JOIN users AS u ON p.user_id = u.id;

internal/endtoend/testdata/sqlc_embed_outer_join_right/sqlite/schema.sql

@@ -0,0 +1,9 @@
+CREATE TABLE users (
+    id integer PRIMARY KEY,
+    name text NOT NULL
+);
+
+CREATE TABLE posts (
+    id integer PRIMARY KEY,
+    user_id integer
+);