go/loader: add paranoid assertions to help diagnose issue 11012
Change-Id: I5e24fe0fb605bdb39de11309e0e3c8ffd7a1eb8b
Reviewed-on: https://go-review.googlesource.com/12842
Reviewed-by: Robert Griesemer <gri@golang.org>
diff --git a/go/loader/loader.go b/go/loader/loader.go
index 5555faa..bbacc5b 100644
--- a/go/loader/loader.go
+++ b/go/loader/loader.go
@@ -406,6 +406,9 @@
// Complete marks ii as complete.
// Its info and err fields will not be subsequently updated.
func (ii *importInfo) Complete(info *PackageInfo, err error) {
+ if info == nil && err == nil {
+ panic("Complete(nil, nil)")
+ }
ii.mu.Lock()
ii.info = info
ii.err = err
@@ -504,8 +507,39 @@
xtestPkgs = append(xtestPkgs, bp)
}
- imp.importedMu.Lock() // (unnecessary, we're sequential here)
- info := imp.imported[path].info // must be non-nil, see above
+ imp.importedMu.Lock() // (unnecessary, we're sequential here)
+ ii, ok := imp.imported[path]
+ // Paranoid checks added due to issue #11012.
+ if !ok {
+ // Unreachable.
+ // The previous loop called loadAll and thus
+ // startLoad for each path in ImportPkgs, which
+ // populates imp.imported[path] with a non-zero value.
+ panic(fmt.Sprintf("imported[%q] not found", path))
+ }
+ if ii == nil {
+ // Unreachable.
+ // The ii values in this loop are the same as in
+ // the previous loop, which enforced the invariant
+ // that at least one of ii.err and ii.info is non-nil.
+ panic(fmt.Sprintf("imported[%q] == nil", path))
+ }
+ if ii.err != nil {
+ // The sole possible cause is failure of the
+ // FindPackage call in (*importer).load,
+ // but we rechecked that condition above.
+ // Perhaps the state of the file system changed
+ // in between? Seems unlikely.
+ panic(fmt.Sprintf("imported[%q].err = %v", path, ii.err))
+ }
+ if ii.info == nil {
+ // Unreachable.
+ // Complete has this postcondition:
+ // ii.err != nil || ii.info != nil
+ // and we know that ii.err == nil here.
+ panic(fmt.Sprintf("imported[%q].info = nil", path))
+ }
+ info := ii.info
imp.importedMu.Unlock()
// Parse the in-package test files.
@@ -786,7 +820,6 @@
}
}
ii.awaitCompletion()
-
}
return result
}
@@ -826,8 +859,6 @@
//
// startLoad is concurrency-safe and idempotent.
//
-// Precondition: path != "unsafe".
-//
func (imp *importer) startLoad(path string) *importInfo {
imp.importedMu.Lock()
ii, ok := imp.imported[path]
