go/analysis/passes/printf: fix regression in "recursive stringer" logic
The recursive stringer check should report cases such as
func (x T) String() string { return fmt.Sprint(x) }
in which the receiver x (or possibly &x) was passed into a fmt print call.
However, in translating it from the go/ast to the go/types representation,
I inadvertently made it report any situation in which a value of type T
was passed to fmt, even when the value is not x, as in:
func (cons *cons) String() string {
... fmt.Sprint(cons.cdr) ...
}
Fixed and tested.
Change-Id: I57e88755c9989deaaad45cc306a604f3db4ee269
Reviewed-on: https://go-review.googlesource.com/c/149616
Reviewed-by: Michael Matloob <matloob@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org>
diff --git a/go/analysis/passes/printf/printf.go b/go/analysis/passes/printf/printf.go
index 80db95c..9fa0a1c 100644
--- a/go/analysis/passes/printf/printf.go
+++ b/go/analysis/passes/printf/printf.go
@@ -843,7 +843,22 @@
}
// Is the expression e within the body of that String method?
- return stringMethod.Pkg() == pass.Pkg && stringMethod.Scope().Contains(e.Pos())
+ if stringMethod.Pkg() != pass.Pkg || !stringMethod.Scope().Contains(e.Pos()) {
+ return false
+ }
+
+ // Is it the receiver r, or &r?
+ recv := stringMethod.Type().(*types.Signature).Recv()
+ if recv == nil {
+ return false
+ }
+ if u, ok := e.(*ast.UnaryExpr); ok && u.Op == token.AND {
+ e = u.X // strip off & from &r
+ }
+ if id, ok := e.(*ast.Ident); ok {
+ return pass.TypesInfo.Uses[id] == recv
+ }
+ return false
}
// isFunctionValue reports whether the expression is a function as opposed to a function call.
diff --git a/go/analysis/passes/printf/testdata/src/a/a.go b/go/analysis/passes/printf/testdata/src/a/a.go
index 603179b..970b512 100644
--- a/go/analysis/passes/printf/testdata/src/a/a.go
+++ b/go/analysis/passes/printf/testdata/src/a/a.go
@@ -514,6 +514,19 @@
return fmt.Sprintln(p) // want "Sprintln arg p causes recursive call to String method"
}
+type cons struct {
+ car int
+ cdr *cons
+}
+
+func (cons *cons) String() string {
+ if cons == nil {
+ return "nil"
+ }
+ _ = fmt.Sprint(cons.cdr) // don't want "recursive call" diagnostic
+ return fmt.Sprintf("(%d . %v)", cons.car, cons.cdr) // don't want "recursive call" diagnostic
+}
+
type BoolFormatter bool
func (*BoolFormatter) Format(fmt.State, rune) {
