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>
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
Alan Donovan