go/analysis/passes/printf: fix false negative with nested pointers
Pointers to compound objects (structs, slices, arrays, maps) are only
followed by fmt if the pointer is at the top level of an argument. This
is to minimise the chances of fmt running into loops.
However, vet did not follow this rule. It likely doesn't help that fmt
does not document that restriction well, which is being tracked in
#28625.
This change was originally made to cmd/vet as
https://go-review.googlesource.com/c/147997.
Updates #27672.
Change-Id: I65944cf355baedb4578af57046e2bbfd3fe6a9dc
Reviewed-on: https://go-review.googlesource.com/c/149319
Reviewed-by: Michael Matloob <matloob@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org>
diff --git a/go/analysis/passes/printf/testdata/src/a/a.go b/go/analysis/passes/printf/testdata/src/a/a.go
index 40e8f2f..603179b 100644
--- a/go/analysis/passes/printf/testdata/src/a/a.go
+++ b/go/analysis/passes/printf/testdata/src/a/a.go
@@ -237,7 +237,7 @@
Printf("%T", someFunction) // ok: maybe someone wants to see the type
// Bug: used to recur forever.
Printf("%p %x", recursiveStructV, recursiveStructV.next)
- Printf("%p %x", recursiveStruct1V, recursiveStruct1V.next)
+ Printf("%p %x", recursiveStruct1V, recursiveStruct1V.next) // want `Printf format %x has arg recursiveStruct1V\.next of wrong type \*a\.RecursiveStruct2`
Printf("%p %x", recursiveSliceV, recursiveSliceV)
Printf("%p %x", recursiveMapV, recursiveMapV)
// Special handling for Log.
@@ -678,6 +678,14 @@
intMap := map[int]int{3: 4}
fmt.Printf("%s", &intMap) // want `Printf format %s has arg &intMap of wrong type \*map\[int\]int`
+
+ type T2 struct {
+ X string
+ }
+ type T1 struct {
+ X *T2
+ }
+ fmt.Printf("%s\n", T1{&T2{"x"}}) // want `Printf format %s has arg T1{&T2{.x.}} of wrong type a\.T1`
}
// Printf wrappers from external package
diff --git a/go/analysis/passes/printf/types.go b/go/analysis/passes/printf/types.go
index 28d94e1..0ebc810 100644
--- a/go/analysis/passes/printf/types.go
+++ b/go/analysis/passes/printf/types.go
@@ -108,9 +108,13 @@
// Check whether the rest can print pointers.
return t&argPointer != 0
}
- // If it's a pointer to a struct, array, slice, or map, that's
- // equivalent in our analysis to whether we can print the type
- // being pointed to.
+ // If it's a top-level pointer to a struct, array, slice, or
+ // map, that's equivalent in our analysis to whether we can
+ // print the type being pointed to. Pointers in nested levels
+ // are not supported to minimize fmt running into loops.
+ if len(inProgress) > 1 {
+ return false
+ }
return matchArgTypeInternal(pass, t, under, arg, inProgress)
case *types.Struct:
