From 2f6f835532243c1cc881c08dbdbaf4bbb593cdb9 Mon Sep 17 00:00:00 2001
From: James Bowes <jbowes@repl.ca>
Date: Wed, 21 Jul 2021 18:18:40 -0300
Subject: [PATCH 1/2] temp

---
 go.mod | 5 ++++-
 go.sum | 2 ++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/go.mod b/go.mod
index 6cef3d0..a4aa145 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,7 @@ module github.com/jbowes/vice
 
 go 1.12
 
-require golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543
+require (
+	github.com/pkg/errors v0.9.1
+	golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543
+)
diff --git a/go.sum b/go.sum
index 3ab73ea..e5210ed 100644
--- a/go.sum
+++ b/go.sum
@@ -1,2 +1,4 @@
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

From 1a98823bbe6092a77f57dd9f8349751703a4517a Mon Sep 17 00:00:00 2001
From: James Bowes <jbowes@repl.ca>
Date: Wed, 21 Jul 2021 20:16:16 -0300
Subject: [PATCH 2/2] Implement frame retrieval and printing locally

Reimplement the xerrors style of frame printing with a local pc. This
will make it easier for future changes to bring compatibility with other
error ecosystems.
---
 skip/error.go   | 21 +++++----------------
 skip/frame.go   | 26 ++++++++++++++++++++++++++
 skip/xerrors.go | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 65 insertions(+), 16 deletions(-)
 create mode 100644 skip/frame.go
 create mode 100644 skip/xerrors.go

diff --git a/skip/error.go b/skip/error.go
index 61eb4a4..4209094 100644
--- a/skip/error.go
+++ b/skip/error.go
@@ -1,10 +1,6 @@
 package skip
 
-import (
-	"fmt"
-
-	"golang.org/x/xerrors"
-)
+import "fmt"
 
 // New returns an error that formats as the given text, and implements the
 // behaviour described by the given Vice. The argument skip is the number of
@@ -97,7 +93,7 @@ func Sealf(err error, v Vice, skip uint, format string, a ...interface{}) error
 }
 
 func sealed(serr *sealError, v Vice, skip uint) error {
-	serr.frame = xerrors.Caller(int(2 + skip))
+	serr.frame = caller(int(2 + skip))
 	switch v {
 	case Timeout:
 		return &timeoutSeal{*serr}
@@ -129,7 +125,7 @@ func sealed(serr *sealError, v Vice, skip uint) error {
 }
 
 func wrapped(werr *wrapError, v Vice, skip uint) error {
-	werr.frame = xerrors.Caller(int(2 + skip))
+	werr.frame = caller(int(2 + skip))
 	switch v {
 	case Timeout:
 		return &timeoutWrap{*werr}
@@ -163,17 +159,10 @@ func wrapped(werr *wrapError, v Vice, skip uint) error {
 type sealError struct {
 	msg   string
 	err   error
-	frame xerrors.Frame
+	frame frame
 }
 
-func (e *sealError) Error() string              { return fmt.Sprint(e) }
-func (e *sealError) Format(s fmt.State, v rune) { xerrors.FormatError(e, s, v) }
-
-func (e *sealError) FormatError(p xerrors.Printer) (next error) {
-	p.Print(e.msg)
-	e.frame.Format(p)
-	return e.err
-}
+func (e *sealError) Error() string { return fmt.Sprint(e) }
 
 type wrapError struct {
 	sealError
diff --git a/skip/frame.go b/skip/frame.go
new file mode 100644
index 0000000..1f96125
--- /dev/null
+++ b/skip/frame.go
@@ -0,0 +1,26 @@
+// frame reimplements stack frame handling in a way that is compatible with
+// multiple error ecosystems.
+
+package skip
+
+import "runtime"
+
+type frame [3]uintptr
+
+func caller(skip int) frame {
+	var f frame
+	runtime.Callers(skip+1, f[:])
+	return f
+}
+
+func (f frame) detail() (string, string, int) {
+	frs := runtime.CallersFrames(f[:])
+
+	if _, ok := frs.Next(); ok {
+		if fr, ok := frs.Next(); ok {
+			return fr.Function, fr.File, fr.Line
+		}
+	}
+
+	return "", "", 0
+}
diff --git a/skip/xerrors.go b/skip/xerrors.go
new file mode 100644
index 0000000..b5b4fdb
--- /dev/null
+++ b/skip/xerrors.go
@@ -0,0 +1,34 @@
+// This file holds xerrors specific logic. xerrors was meant to be the
+// behaviour that would land in the standard library in go 1.13. Not all
+// of it did, but this still remains the default for vice. Still, it is kept
+// in its own file to make it easier to remove or put behind a build tag.
+
+package skip
+
+import (
+	"fmt"
+
+	"golang.org/x/xerrors"
+)
+
+func (e *sealError) Format(s fmt.State, v rune) { xerrors.FormatError(e, s, v) }
+
+func (e *sealError) FormatError(p xerrors.Printer) (next error) {
+	p.Print(e.msg)
+	e.frame.Format(p)
+	return e.err
+}
+
+func (f frame) Format(p xerrors.Printer) {
+	if !p.Detail() {
+		return
+	}
+
+	fn, file, line := f.detail()
+	if fn != "" {
+		p.Printf("%s\n    ", fn)
+	}
+	if file != "" {
+		p.Printf("%s:%d\n", file, line)
+	}
+}