It's possible to use a type which implements fmt.Formatter without
importing fmt directly, if the type is imported from another package
such as math/big.
On top of that, it's possible to use printf-like functions without
importing fmt directly, such as using testing.T.Logf.
These two scenarios combined can lead to the printf check not finding
the fmt.Formatter type, since it's not a direct dependency of the root
package.
fmt must still be in the import graph somewhere, so we could search for
it via types.Package.Imports. However, at that point it's simpler to
just look for the Format method manually via go/types.
Fixes#30399.
Change-Id: Id78454bb6a51b3c5e1bcb1984a7fbfb4a29a5be0
Reviewed-on: https://go-review.googlesource.com/c/163817
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>
The first issue is that %b and %o can print pointers, but printVerbs
didn't reflect that:
The %b, %d, %o, %x and %X verbs also work with pointers,
formatting the value exactly as if it were an integer.
The second issue is that arrays can never be printed as pointers. This
was previously reported as part of #27672.
The third issue is that only %p can print all slices, maps, and
functions as if they were pointers. This differs from verbs like %b or
%o, which can't print these types as pointers.
Fix all of the issues above, and add extensive test cases covering all
the combinations. Verified all of them with an executed program. The
amount of test cases is perhaps overkill, but this is not the first time
we've gotten the printf pointer logic wrong.
Updates #27672.
Fixes#28858.
Change-Id: I62eb79d505fd1e250a16b90bda3c68b702f35a29
Reviewed-on: https://go-review.googlesource.com/c/149979
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>
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>
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>
fmt's godoc reads:
For compound objects, the elements are printed using these
rules, recursively, laid out like this:
struct: {field0 field1 ...}
array, slice: [elem0 elem1 ...]
maps: map[key1:value1 key2:value2 ...]
pointer to above: &{}, &[], &map[]
That is, a pointer to a struct, array, slice, or map, can be correctly
printed by fmt if the type pointed to can be printed without issues.
vet was only following this rule for pointers to structs, omitting
arrays, slices, and maps. Fix that, and add tests for all the
combinations.
This change was originally made to cmd/vet in
https://go-review.googlesource.com/c/147758
Updates #27672.
Change-Id: I7e25ecaeed619ae8b6ada79bccacba6b67171733
Reviewed-on: https://go-review.googlesource.com/c/149318
Reviewed-by: Michael Matloob <matloob@golang.org>
Guide to changes:
- The -printfuncs flag is renamed -printf.funcs.
It no longer supports "pkg.T.f" form, requiring instead
"(dir/pkg.T).f" or "(*dir/pkg.T).f".
The legacy ":%d" suffix is no longer supported.
- (*testing.T).Errorf and friends are removed from the isPrint map
because they are discovered by induction while analyzing package
"testing".
- localPrintfLike map operations are replaced by the Fact mechanism.
- The go/types representation is used instead of strings/ast.Nodes in
various places. For example:
pkgpath, name string -> *types.Func (to identify a function)
format, args *ast.Field -> *types.Var (to identify format/args params)
This was required to fix a latent bug in maybePrintfWrapper's
handling of format string parameters` declared using "factored"
syntax, such as: func f(foo, format string, args...interface{}).
See L253 of the original testdata file for a testcase that ensured
the buggy (?) behavior.
- func printfLike is removed as it was deadcode.
- isFormatter is rewritten to avoid a global variable.
- "if verbose { warn }" is replaced by "if false { report }" for now.
- recursive stringer is rewritten more simply in term of go/types.
Change-Id: Ia6ee827117b611c686e38207916a21fe1fc296e2
Reviewed-on: https://go-review.googlesource.com/c/142239
Reviewed-by: Michael Matloob <matloob@golang.org>
Daniel Martí
Marcel van Lohuizen
Alan Donovan