chore(coderd/database/gen): improve generated fake stub (#8088)

* chore(coderd/database/gen): generate arg validation where applicable
* fix(coderd/database/gen): support pointers and slices as return types

coderd/database/gen/fake/main.go

@@ -1,10 +1,12 @@
 package main
 
 import (
+	"fmt"
 	"go/format"
 	"go/token"
 	"log"
 	"os"
+	"path"
 
 	"github.com/dave/dst"
 	"github.com/dave/dst/decorator"
@@ -65,6 +67,76 @@ func run() error {
 	}
 
 	for _, fn := range funcs {
+		var bodyStmts []dst.Stmt
+		if len(fn.Func.Params.List) == 2 && fn.Func.Params.List[1].Names[0].Name == "arg" {
+			/*
+				err := validateDatabaseType(arg)
+				if err != nil {
+					return database.User{}, err
+				}
+			*/
+			bodyStmts = append(bodyStmts, &dst.AssignStmt{
+				Lhs: []dst.Expr{dst.NewIdent("err")},
+				Tok: token.DEFINE,
+				Rhs: []dst.Expr{
+					&dst.CallExpr{
+						Fun: &dst.Ident{
+							Name: "validateDatabaseType",
+						},
+						Args: []dst.Expr{dst.NewIdent("arg")},
+					},
+				},
+			})
+			returnStmt := &dst.ReturnStmt{
+				Results: []dst.Expr{}, // Filled below.
+			}
+			bodyStmts = append(bodyStmts, &dst.IfStmt{
+				Cond: &dst.BinaryExpr{
+					X:  dst.NewIdent("err"),
+					Op: token.NEQ,
+					Y:  dst.NewIdent("nil"),
+				},
+				Body: &dst.BlockStmt{
+					List: []dst.Stmt{
+						returnStmt,
+					},
+				},
+				Decs: dst.IfStmtDecorations{
+					NodeDecs: dst.NodeDecs{
+						After: dst.EmptyLine,
+					},
+				},
+			})
+			for _, r := range fn.Func.Results.List {
+				switch typ := r.Type.(type) {
+				case *dst.StarExpr, *dst.ArrayType:
+					returnStmt.Results = append(returnStmt.Results, dst.NewIdent("nil"))
+				case *dst.Ident:
+					if typ.Path != "" {
+						returnStmt.Results = append(returnStmt.Results, dst.NewIdent(fmt.Sprintf("%s.%s{}", path.Base(typ.Path), typ.Name)))
+					} else {
+						switch typ.Name {
+						case "uint8", "uint16", "uint32", "uint64", "uint", "uintptr",
+							"int8", "int16", "int32", "int64", "int",
+							"byte", "rune",
+							"float32", "float64",
+							"complex64", "complex128":
+							returnStmt.Results = append(returnStmt.Results, dst.NewIdent("0"))
+						case "string":
+							returnStmt.Results = append(returnStmt.Results, dst.NewIdent("\"\""))
+						case "bool":
+							returnStmt.Results = append(returnStmt.Results, dst.NewIdent("false"))
+						case "error":
+							returnStmt.Results = append(returnStmt.Results, dst.NewIdent("err"))
+						default:
+							panic(fmt.Sprintf("unknown ident: %#v", r.Type))
+						}
+					}
+				default:
+					panic(fmt.Sprintf("unknown return type: %T", r.Type))
+				}
+			}
+		}
 		decl, ok := declByName[fn.Name]
 		if !ok {
 			// Not implemented!
@@ -90,8 +162,7 @@ func run() error {
 					},
 				},
 				Body: &dst.BlockStmt{
-					List: []dst.Stmt{
+					List: append(bodyStmts, &dst.ExprStmt{
-						&dst.ExprStmt{
 						X: &dst.CallExpr{
 							Fun: &dst.Ident{
 								Name: "panic",
@@ -103,8 +174,7 @@ func run() error {
 								},
 							},
 						},
-						},
+					}),
-					},
 				},
 			}
 		}
@@ -178,11 +248,27 @@ func readStoreInterface() ([]storeMethod, error) {
 			if t == nil {
 				continue
 			}
+			var (
+				ident *dst.Ident
+				ok    bool
+			)
 			for _, f := range t.List {
-				ident, ok := f.Type.(*dst.Ident)
+				switch typ := f.Type.(type) {
+				case *dst.StarExpr:
+					ident, ok = typ.X.(*dst.Ident)
 					if !ok {
 						continue
 					}
+				case *dst.ArrayType:
+					ident, ok = typ.Elt.(*dst.Ident)
+					if !ok {
+						continue
+					}
+				case *dst.Ident:
+					ident = typ
+				default:
+					continue
+				}
 				if !ident.IsExported() {
 					continue
 				}