Respect the engine selector on global Go type overrides

Global overrides are shared by every SQL package, but the Go codegen
applied all of them regardless of their engine field, so a multi-engine
config got the first matching go_type and last matching struct tag in
every package. Drop global overrides scoped to a different engine
before parsing them.

Fixes #4624

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EbVEZseeSLEVPCsmiPymrg

Author: claude

internal/codegen/golang/opts/options.go

@@ -153,11 +153,19 @@ func parseGlobalOpts(req *plugin.GenerateRequest) (*GlobalOptions, error) {
 	if err := json.Unmarshal(req.GlobalOptions, &options); err != nil {
 		return nil, fmt.Errorf("unmarshalling global options: %w", err)
 	}
-	for i := range options.Overrides {
-		if err := options.Overrides[i].parse(req); err != nil {
+	// Global overrides are shared by every SQL package, so drop the ones
+	// scoped to a different engine
+	overrides := options.Overrides[:0]
+	for _, o := range options.Overrides {
+		if o.Engine != "" && o.Engine != req.Settings.GetEngine() {
+			continue
+		}
+		if err := o.parse(req); err != nil {
 			return nil, err
 		}
+		overrides = append(overrides, o)
 	}
+	options.Overrides = overrides
 	return &options, nil
 }
 

internal/endtoend/testdata/overrides_global_engine/mysql/db.go

@@ -0,0 +1,3 @@
+-- name: FindEntry :one
+SELECT id, value, code FROM entries
+WHERE value = sqlc.arg(value) AND code = sqlc.arg(code);

internal/endtoend/testdata/overrides_global_engine/mysql/models.go

@@ -0,0 +1,5 @@
+CREATE TABLE entries (
+    id integer NOT NULL,
+    value text NOT NULL,
+    code text NOT NULL
+);

internal/endtoend/testdata/overrides_global_engine/mysql/query.sql.go

@@ -0,0 +1,53 @@
+version: "2"
+overrides:
+  go:
+    overrides:
+      - db_type: text
+        engine: postgresql
+        go_type: string
+        go_struct_tag: 'backend:"postgresql"'
+      - db_type: text
+        engine: mysql
+        go_type: "database/sql.NullString"
+        go_struct_tag: 'backend:"mysql"'
+      - db_type: text
+        engine: sqlite
+        go_type:
+          type: byte
+          slice: true
+        go_struct_tag: 'backend:"sqlite"'
+      - column: entries.code
+        engine: postgresql
+        go_type:
+          import: encoding/json
+          type: RawMessage
+      - column: entries.code
+        engine: mysql
+        go_type:
+          type: byte
+          slice: true
+      - column: entries.code
+        engine: sqlite
+        go_type: string
+sql:
+  - engine: postgresql
+    schema: schema.sql
+    queries: query.sql
+    gen:
+      go:
+        package: pg
+        out: pg
+  - engine: mysql
+    schema: schema.sql
+    queries: query.sql
+    gen:
+      go:
+        package: mysql
+        out: mysql
+  - engine: sqlite
+    schema: schema.sql
+    queries: query.sql
+    gen:
+      go:
+        package: sqlite
+        out: sqlite