cmd/go/internal/mvs: export a NewBuildListError function
Also factor out BuildListError to a separate file.
For #36460
Change-Id: Ibd1143893b09a2bbef659bea1e8c5dd35184a7ef
Reviewed-on: https://go-review.googlesource.com/c/go/+/247764
Reviewed-by: Jay Conrod <jayconrod@google.com>
diff --git a/src/cmd/go/internal/mvs/errors.go b/src/cmd/go/internal/mvs/errors.go
new file mode 100644
index 0000000..8577902
--- /dev/null
+++ b/src/cmd/go/internal/mvs/errors.go
@@ -0,0 +1,96 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package mvs
+
+import (
+ "fmt"
+ "strings"
+
+ "golang.org/x/mod/module"
+)
+
+// BuildListError decorates an error that occurred gathering requirements
+// while constructing a build list. BuildListError prints the chain
+// of requirements to the module where the error occurred.
+type BuildListError struct {
+ Err error
+ stack []buildListErrorElem
+}
+
+type buildListErrorElem struct {
+ m module.Version
+
+ // nextReason is the reason this module depends on the next module in the
+ // stack. Typically either "requires", or "updating to".
+ nextReason string
+}
+
+// NewBuildListError returns a new BuildListError wrapping an error that
+// occurred at a module found along the given path of requirements and/or
+// upgrades, which must be non-empty.
+//
+// The isUpgrade function reports whether a path step is due to an upgrade.
+// A nil isUpgrade function indicates that none of the path steps are due to upgrades.
+func NewBuildListError(err error, path []module.Version, isUpgrade func(from, to module.Version) bool) *BuildListError {
+ stack := make([]buildListErrorElem, 0, len(path))
+ for len(path) > 1 {
+ reason := "requires"
+ if isUpgrade != nil && isUpgrade(path[0], path[1]) {
+ reason = "updating to"
+ }
+ stack = append(stack, buildListErrorElem{
+ m: path[0],
+ nextReason: reason,
+ })
+ path = path[1:]
+ }
+ stack = append(stack, buildListErrorElem{m: path[0]})
+
+ return &BuildListError{
+ Err: err,
+ stack: stack,
+ }
+}
+
+// Module returns the module where the error occurred. If the module stack
+// is empty, this returns a zero value.
+func (e *BuildListError) Module() module.Version {
+ if len(e.stack) == 0 {
+ return module.Version{}
+ }
+ return e.stack[len(e.stack)-1].m
+}
+
+func (e *BuildListError) Error() string {
+ b := &strings.Builder{}
+ stack := e.stack
+
+ // Don't print modules at the beginning of the chain without a
+ // version. These always seem to be the main module or a
+ // synthetic module ("target@").
+ for len(stack) > 0 && stack[0].m.Version == "" {
+ stack = stack[1:]
+ }
+
+ if len(stack) == 0 {
+ b.WriteString(e.Err.Error())
+ } else {
+ for _, elem := range stack[:len(stack)-1] {
+ fmt.Fprintf(b, "%s@%s %s\n\t", elem.m.Path, elem.m.Version, elem.nextReason)
+ }
+ // Ensure that the final module path and version are included as part of the
+ // error message.
+ m := stack[len(stack)-1].m
+ if _, ok := e.Err.(*module.ModuleError); ok {
+ // TODO(bcmills): Also ensure that the module path and version match.
+ // (Otherwise, we may be reporting an error from a replacement without
+ // indicating the replacement path.)
+ fmt.Fprintf(b, "%v", e.Err)
+ } else {
+ fmt.Fprintf(b, "%v", module.VersionError(m, e.Err))
+ }
+ }
+ return b.String()
+}
diff --git a/src/cmd/go/internal/mvs/mvs.go b/src/cmd/go/internal/mvs/mvs.go
index 1056a50..ea23a9f 100644
--- a/src/cmd/go/internal/mvs/mvs.go
+++ b/src/cmd/go/internal/mvs/mvs.go
@@ -9,7 +9,6 @@
import (
"fmt"
"sort"
- "strings"
"sync"
"sync/atomic"
@@ -61,59 +60,6 @@
Previous(m module.Version) (module.Version, error)
}
-// BuildListError decorates an error that occurred gathering requirements
-// while constructing a build list. BuildListError prints the chain
-// of requirements to the module where the error occurred.
-type BuildListError struct {
- Err error
- stack []buildListErrorElem
-}
-
-type buildListErrorElem struct {
- m module.Version
-
- // nextReason is the reason this module depends on the next module in the
- // stack. Typically either "requires", or "upgraded to".
- nextReason string
-}
-
-// Module returns the module where the error occurred. If the module stack
-// is empty, this returns a zero value.
-func (e *BuildListError) Module() module.Version {
- if len(e.stack) == 0 {
- return module.Version{}
- }
- return e.stack[len(e.stack)-1].m
-}
-
-func (e *BuildListError) Error() string {
- b := &strings.Builder{}
- stack := e.stack
-
- // Don't print modules at the beginning of the chain without a
- // version. These always seem to be the main module or a
- // synthetic module ("target@").
- for len(stack) > 0 && stack[0].m.Version == "" {
- stack = stack[1:]
- }
-
- if len(stack) == 0 {
- b.WriteString(e.Err.Error())
- } else {
- for _, elem := range stack[:len(stack)-1] {
- fmt.Fprintf(b, "%s@%s %s\n\t", elem.m.Path, elem.m.Version, elem.nextReason)
- }
- // Ensure that the final module path and version are included as part of the
- // error message.
- if _, ok := e.Err.(*module.ModuleError); ok {
- fmt.Fprintf(b, "%v", e.Err)
- } else {
- fmt.Fprintf(b, "%v", module.VersionError(stack[len(stack)-1].m, e.Err))
- }
- }
- return b.String()
-}
-
// BuildList returns the build list for the target module.
//
// target is the root vertex of a module requirement graph. For cmd/go, this is
@@ -202,29 +148,30 @@
q = q[1:]
if node.err != nil {
- // Construct the stack reversed (from the error to the main module),
+ pathUpgrade := map[module.Version]module.Version{}
+
+ // Construct the error path reversed (from the error to the main module),
// then reverse it to obtain the usual order (from the main module to
// the error).
- stack := []buildListErrorElem{{m: node.m}}
+ errPath := []module.Version{node.m}
for n, prev := neededBy[node], node; n != nil; n, prev = neededBy[n], n {
- reason := "requires"
if n.upgrade == prev.m {
- reason = "updating to"
+ pathUpgrade[n.m] = prev.m
}
- stack = append(stack, buildListErrorElem{m: n.m, nextReason: reason})
+ errPath = append(errPath, n.m)
}
- i, j := 0, len(stack)-1
+ i, j := 0, len(errPath)-1
for i < j {
- stack[i], stack[j] = stack[j], stack[i]
+ errPath[i], errPath[j] = errPath[j], errPath[i]
i++
j--
}
- err := &BuildListError{
- Err: node.err,
- stack: stack,
+ isUpgrade := func(from, to module.Version) bool {
+ return pathUpgrade[from] == to
}
- return nil, err
+
+ return nil, NewBuildListError(node.err, errPath, isUpgrade)
}
neighbors := node.required
