bump to modernc.org/sqlite v1.29.7 (#2850)

5 files changed, 455 insertions, 145 deletions

diff --git a/vendor/golang.org/x/tools/internal/imports/fix.go b/vendor/golang.org/x/tools/internal/imports/fix.go
index dd369c072..6a18f63a4 100644
--- a/vendor/golang.org/x/tools/internal/imports/fix.go
+++ b/vendor/golang.org/x/tools/internal/imports/fix.go
@@ -13,6 +13,7 @@ import (
 	"go/build"
 	"go/parser"
 	"go/token"
+	"go/types"
 	"io/fs"
 	"io/ioutil"
 	"os"
@@ -700,20 +701,21 @@ func ScoreImportPaths(ctx context.Context, env *ProcessEnv, paths []string) (map
 	return result, nil
 }
 
-func PrimeCache(ctx context.Context, env *ProcessEnv) error {
+func PrimeCache(ctx context.Context, resolver Resolver) error {
 	// Fully scan the disk for directories, but don't actually read any Go files.
 	callback := &scanCallback{
-		rootFound: func(gopathwalk.Root) bool {
-			return true
+		rootFound: func(root gopathwalk.Root) bool {
+			// See getCandidatePkgs: walking GOROOT is apparently expensive and
+			// unnecessary.
+			return root.Type != gopathwalk.RootGOROOT
 		},
 		dirFound: func(pkg *pkg) bool {
 			return false
 		},
-		packageNameLoaded: func(pkg *pkg) bool {
-			return false
-		},
+		// packageNameLoaded and exportsLoaded must never be called.
 	}
-	return getCandidatePkgs(ctx, callback, "", "", env)
+
+	return resolver.scan(ctx, callback)
 }
 
 func candidateImportName(pkg *pkg) string {
@@ -827,16 +829,45 @@ func GetPackageExports(ctx context.Context, wrapped func(PackageExport), searchP
 	return getCandidatePkgs(ctx, callback, filename, filePkg, env)
 }
 
-var requiredGoEnvVars = []string{"GO111MODULE", "GOFLAGS", "GOINSECURE", "GOMOD", "GOMODCACHE", "GONOPROXY", "GONOSUMDB", "GOPATH", "GOPROXY", "GOROOT", "GOSUMDB", "GOWORK"}
+// TODO(rfindley): we should depend on GOOS and GOARCH, to provide accurate
+// imports when doing cross-platform development.
+var requiredGoEnvVars = []string{
+	"GO111MODULE",
+	"GOFLAGS",
+	"GOINSECURE",
+	"GOMOD",
+	"GOMODCACHE",
+	"GONOPROXY",
+	"GONOSUMDB",
+	"GOPATH",
+	"GOPROXY",
+	"GOROOT",
+	"GOSUMDB",
+	"GOWORK",
+}
 
 // ProcessEnv contains environment variables and settings that affect the use of
 // the go command, the go/build package, etc.
+//
+// ...a ProcessEnv *also* overwrites its Env along with derived state in the
+// form of the resolver. And because it is lazily initialized, an env may just
+// be broken and unusable, but there is no way for the caller to detect that:
+// all queries will just fail.
+//
+// TODO(rfindley): refactor this package so that this type (perhaps renamed to
+// just Env or Config) is an immutable configuration struct, to be exchanged
+// for an initialized object via a constructor that returns an error. Perhaps
+// the signature should be `func NewResolver(*Env) (*Resolver, error)`, where
+// resolver is a concrete type used for resolving imports. Via this
+// refactoring, we can avoid the need to call ProcessEnv.init and
+// ProcessEnv.GoEnv everywhere, and implicitly fix all the places where this
+// these are misused. Also, we'd delegate the caller the decision of how to
+// handle a broken environment.
 type ProcessEnv struct {
 	GocmdRunner *gocommand.Runner
 
 	BuildFlags []string
 	ModFlag    string
-	ModFile    string
 
 	// SkipPathInScan returns true if the path should be skipped from scans of
 	// the RootCurrentModule root type. The function argument is a clean,
@@ -846,7 +877,7 @@ type ProcessEnv struct {
 	// Env overrides the OS environment, and can be used to specify
 	// GOPROXY, GO111MODULE, etc. PATH cannot be set here, because
 	// exec.Command will not honor it.
-	// Specifying all of RequiredGoEnvVars avoids a call to `go env`.
+	// Specifying all of requiredGoEnvVars avoids a call to `go env`.
 	Env map[string]string
 
 	WorkingDir string
@@ -854,9 +885,17 @@ type ProcessEnv struct {
 	// If Logf is non-nil, debug logging is enabled through this function.
 	Logf func(format string, args ...interface{})
 
-	initialized bool
+	// If set, ModCache holds a shared cache of directory info to use across
+	// multiple ProcessEnvs.
+	ModCache *DirInfoCache
 
-	resolver Resolver
+	initialized bool // see TODO above
+
+	// resolver and resolverErr are lazily evaluated (see GetResolver).
+	// This is unclean, but see the big TODO in the docstring for ProcessEnv
+	// above: for now, we can't be sure that the ProcessEnv is fully initialized.
+	resolver    Resolver
+	resolverErr error
 }
 
 func (e *ProcessEnv) goEnv() (map[string]string, error) {
@@ -936,20 +975,31 @@ func (e *ProcessEnv) env() []string {
 }
 
 func (e *ProcessEnv) GetResolver() (Resolver, error) {
-	if e.resolver != nil {
-		return e.resolver, nil
-	}
 	if err := e.init(); err != nil {
 		return nil, err
 	}
-	if len(e.Env["GOMOD"]) == 0 && len(e.Env["GOWORK"]) == 0 {
-		e.resolver = newGopathResolver(e)
-		return e.resolver, nil
+
+	if e.resolver == nil && e.resolverErr == nil {
+		// TODO(rfindley): we should only use a gopathResolver here if the working
+		// directory is actually *in* GOPATH. (I seem to recall an open gopls issue
+		// for this behavior, but I can't find it).
+		//
+		// For gopls, we can optionally explicitly choose a resolver type, since we
+		// already know the view type.
+		if len(e.Env["GOMOD"]) == 0 && len(e.Env["GOWORK"]) == 0 {
+			e.resolver = newGopathResolver(e)
+		} else {
+			e.resolver, e.resolverErr = newModuleResolver(e, e.ModCache)
+		}
 	}
-	e.resolver = newModuleResolver(e)
-	return e.resolver, nil
+
+	return e.resolver, e.resolverErr
 }
 
+// buildContext returns the build.Context to use for matching files.
+//
+// TODO(rfindley): support dynamic GOOS, GOARCH here, when doing cross-platform
+// development.
 func (e *ProcessEnv) buildContext() (*build.Context, error) {
 	ctx := build.Default
 	goenv, err := e.goEnv()
@@ -1029,15 +1079,23 @@ func addStdlibCandidates(pass *pass, refs references) error {
 type Resolver interface {
 	// loadPackageNames loads the package names in importPaths.
 	loadPackageNames(importPaths []string, srcDir string) (map[string]string, error)
+
 	// scan works with callback to search for packages. See scanCallback for details.
 	scan(ctx context.Context, callback *scanCallback) error
+
 	// loadExports returns the set of exported symbols in the package at dir.
 	// loadExports may be called concurrently.
 	loadExports(ctx context.Context, pkg *pkg, includeTest bool) (string, []string, error)
+
 	// scoreImportPath returns the relevance for an import path.
 	scoreImportPath(ctx context.Context, path string) float64
 
-	ClearForNewScan()
+	// ClearForNewScan returns a new Resolver based on the receiver that has
+	// cleared its internal caches of directory contents.
+	//
+	// The new resolver should be primed and then set via
+	// [ProcessEnv.UpdateResolver].
+	ClearForNewScan() Resolver
 }
 
 // A scanCallback controls a call to scan and receives its results.
@@ -1120,7 +1178,7 @@ func addExternalCandidates(ctx context.Context, pass *pass, refs references, fil
 		go func(pkgName string, symbols map[string]bool) {
 			defer wg.Done()
 
-			found, err := findImport(ctx, pass, found[pkgName], pkgName, symbols, filename)
+			found, err := findImport(ctx, pass, found[pkgName], pkgName, symbols)
 
 			if err != nil {
 				firstErrOnce.Do(func() {
@@ -1151,6 +1209,17 @@ func addExternalCandidates(ctx context.Context, pass *pass, refs references, fil
 	}()
 
 	for result := range results {
+		// Don't offer completions that would shadow predeclared
+		// names, such as github.com/coreos/etcd/error.
+		if types.Universe.Lookup(result.pkg.name) != nil { // predeclared
+			// Ideally we would skip this candidate only
+			// if the predeclared name is actually
+			// referenced by the file, but that's a lot
+			// trickier to compute and would still create
+			// an import that is likely to surprise the
+			// user before long.
+			continue
+		}
 		pass.addCandidate(result.imp, result.pkg)
 	}
 	return firstErr
@@ -1193,31 +1262,22 @@ func ImportPathToAssumedName(importPath string) string {
 type gopathResolver struct {
 	env      *ProcessEnv
 	walked   bool
-	cache    *dirInfoCache
+	cache    *DirInfoCache
 	scanSema chan struct{} // scanSema prevents concurrent scans.
 }
 
 func newGopathResolver(env *ProcessEnv) *gopathResolver {
 	r := &gopathResolver{
-		env: env,
-		cache: &dirInfoCache{
-			dirs:      map[string]*directoryPackageInfo{},
-			listeners: map[*int]cacheListener{},
-		},
+		env:      env,
+		cache:    NewDirInfoCache(),
 		scanSema: make(chan struct{}, 1),
 	}
 	r.scanSema <- struct{}{}
 	return r
 }
 
-func (r *gopathResolver) ClearForNewScan() {
-	<-r.scanSema
-	r.cache = &dirInfoCache{
-		dirs:      map[string]*directoryPackageInfo{},
-		listeners: map[*int]cacheListener{},
-	}
-	r.walked = false
-	r.scanSema <- struct{}{}
+func (r *gopathResolver) ClearForNewScan() Resolver {
+	return newGopathResolver(r.env)
 }
 
 func (r *gopathResolver) loadPackageNames(importPaths []string, srcDir string) (map[string]string, error) {
@@ -1538,7 +1598,7 @@ func loadExportsFromFiles(ctx context.Context, env *ProcessEnv, dir string, incl
 
 // findImport searches for a package with the given symbols.
 // If no package is found, findImport returns ("", false, nil)
-func findImport(ctx context.Context, pass *pass, candidates []pkgDistance, pkgName string, symbols map[string]bool, filename string) (*pkg, error) {
+func findImport(ctx context.Context, pass *pass, candidates []pkgDistance, pkgName string, symbols map[string]bool) (*pkg, error) {
 	// Sort the candidates by their import package length,
 	// assuming that shorter package names are better than long
 	// ones.  Note that this sorts by the de-vendored name, so
diff --git a/vendor/golang.org/x/tools/internal/imports/imports.go b/vendor/golang.org/x/tools/internal/imports/imports.go
index 58e637b90..660407548 100644
--- a/vendor/golang.org/x/tools/internal/imports/imports.go
+++ b/vendor/golang.org/x/tools/internal/imports/imports.go
@@ -236,7 +236,7 @@ func parse(fset *token.FileSet, filename string, src []byte, opt *Options) (*ast
 			src = src[:len(src)-len("}\n")]
 			// Gofmt has also indented the function body one level.
 			// Remove that indent.
-			src = bytes.Replace(src, []byte("\n\t"), []byte("\n"), -1)
+			src = bytes.ReplaceAll(src, []byte("\n\t"), []byte("\n"))
 			return matchSpace(orig, src)
 		}
 		return file, adjust, nil
diff --git a/vendor/golang.org/x/tools/internal/imports/mod.go b/vendor/golang.org/x/tools/internal/imports/mod.go
index 5f4d435d3..3d0f38f6c 100644
--- a/vendor/golang.org/x/tools/internal/imports/mod.go
+++ b/vendor/golang.org/x/tools/internal/imports/mod.go
@@ -23,49 +23,88 @@ import (
 	"golang.org/x/tools/internal/gopathwalk"
 )
 
-// ModuleResolver implements resolver for modules using the go command as little
-// as feasible.
+// Notes(rfindley): ModuleResolver appears to be heavily optimized for scanning
+// as fast as possible, which is desirable for a call to goimports from the
+// command line, but it doesn't work as well for gopls, where it suffers from
+// slow startup (golang/go#44863) and intermittent hanging (golang/go#59216),
+// both caused by populating the cache, albeit in slightly different ways.
+//
+// A high level list of TODOs:
+//  - Optimize the scan itself, as there is some redundancy statting and
+//    reading go.mod files.
+//  - Invert the relationship between ProcessEnv and Resolver (see the
+//    docstring of ProcessEnv).
+//  - Make it easier to use an external resolver implementation.
+//
+// Smaller TODOs are annotated in the code below.
+
+// ModuleResolver implements the Resolver interface for a workspace using
+// modules.
+//
+// A goal of the ModuleResolver is to invoke the Go command as little as
+// possible. To this end, it runs the Go command only for listing module
+// information (i.e. `go list -m -e -json ...`). Package scanning, the process
+// of loading package information for the modules, is implemented internally
+// via the scan method.
+//
+// It has two types of state: the state derived from the go command, which
+// is populated by init, and the state derived from scans, which is populated
+// via scan. A root is considered scanned if it has been walked to discover
+// directories. However, if the scan did not require additional information
+// from the directory (such as package name or exports), the directory
+// information itself may be partially populated. It will be lazily filled in
+// as needed by scans, using the scanCallback.
 type ModuleResolver struct {
-	env            *ProcessEnv
-	moduleCacheDir string
-	dummyVendorMod *gocommand.ModuleJSON // If vendoring is enabled, the pseudo-module that represents the /vendor directory.
-	roots          []gopathwalk.Root
-	scanSema       chan struct{} // scanSema prevents concurrent scans and guards scannedRoots.
-	scannedRoots   map[gopathwalk.Root]bool
-
-	initialized   bool
-	mains         []*gocommand.ModuleJSON
-	mainByDir     map[string]*gocommand.ModuleJSON
-	modsByModPath []*gocommand.ModuleJSON // All modules, ordered by # of path components in module Path...
-	modsByDir     []*gocommand.ModuleJSON // ...or number of path components in their Dir.
-
-	// moduleCacheCache stores information about the module cache.
-	moduleCacheCache *dirInfoCache
-	otherCache       *dirInfoCache
+	env *ProcessEnv
+
+	// Module state, populated during construction
+	dummyVendorMod *gocommand.ModuleJSON            // if vendoring is enabled, a pseudo-module to represent the /vendor directory
+	moduleCacheDir string                           // GOMODCACHE, inferred from GOPATH if unset
+	roots          []gopathwalk.Root                // roots to scan, in approximate order of importance
+	mains          []*gocommand.ModuleJSON          // main modules
+	mainByDir      map[string]*gocommand.ModuleJSON // module information by dir, to join with roots
+	modsByModPath  []*gocommand.ModuleJSON          // all modules, ordered by # of path components in their module path
+	modsByDir      []*gocommand.ModuleJSON          // ...or by the number of path components in their Dir.
+
+	// Scanning state, populated by scan
+
+	// scanSema prevents concurrent scans, and guards scannedRoots and the cache
+	// fields below (though the caches themselves are concurrency safe).
+	// Receive to acquire, send to release.
+	scanSema     chan struct{}
+	scannedRoots map[gopathwalk.Root]bool // if true, root has been walked
+
+	// Caches of directory info, populated by scans and scan callbacks
+	//
+	// moduleCacheCache stores cached information about roots in the module
+	// cache, which are immutable and therefore do not need to be invalidated.
+	//
+	// otherCache stores information about all other roots (even GOROOT), which
+	// may change.
+	moduleCacheCache *DirInfoCache
+	otherCache       *DirInfoCache
 }
 
-func newModuleResolver(e *ProcessEnv) *ModuleResolver {
+// newModuleResolver returns a new module-aware goimports resolver.
+//
+// Note: use caution when modifying this constructor: changes must also be
+// reflected in ModuleResolver.ClearForNewScan.
+func newModuleResolver(e *ProcessEnv, moduleCacheCache *DirInfoCache) (*ModuleResolver, error) {
 	r := &ModuleResolver{
 		env:      e,
 		scanSema: make(chan struct{}, 1),
 	}
-	r.scanSema <- struct{}{}
-	return r
-}
-
-func (r *ModuleResolver) init() error {
-	if r.initialized {
-		return nil
-	}
+	r.scanSema <- struct{}{} // release
 
 	goenv, err := r.env.goEnv()
 	if err != nil {
-		return err
+		return nil, err
 	}
+
+	// TODO(rfindley): can we refactor to share logic with r.env.invokeGo?
 	inv := gocommand.Invocation{
 		BuildFlags: r.env.BuildFlags,
 		ModFlag:    r.env.ModFlag,
-		ModFile:    r.env.ModFile,
 		Env:        r.env.env(),
 		Logf:       r.env.Logf,
 		WorkingDir: r.env.WorkingDir,
@@ -77,9 +116,12 @@ func (r *ModuleResolver) init() error {
 	// Module vendor directories are ignored in workspace mode:
 	// https://go.googlesource.com/proposal/+/master/design/45713-workspace.md
 	if len(r.env.Env["GOWORK"]) == 0 {
+		// TODO(rfindley): VendorEnabled runs the go command to get GOFLAGS, but
+		// they should be available from the ProcessEnv. Can we avoid the redundant
+		// invocation?
 		vendorEnabled, mainModVendor, err = gocommand.VendorEnabled(context.TODO(), inv, r.env.GocmdRunner)
 		if err != nil {
-			return err
+			return nil, err
 		}
 	}
 
@@ -100,19 +142,14 @@ func (r *ModuleResolver) init() error {
 		// GO111MODULE=on. Other errors are fatal.
 		if err != nil {
 			if errMsg := err.Error(); !strings.Contains(errMsg, "working directory is not part of a module") && !strings.Contains(errMsg, "go.mod file not found") {
-				return err
+				return nil, err
 			}
 		}
 	}
 
-	if gmc := r.env.Env["GOMODCACHE"]; gmc != "" {
-		r.moduleCacheDir = gmc
-	} else {
-		gopaths := filepath.SplitList(goenv["GOPATH"])
-		if len(gopaths) == 0 {
-			return fmt.Errorf("empty GOPATH")
-		}
-		r.moduleCacheDir = filepath.Join(gopaths[0], "/pkg/mod")
+	r.moduleCacheDir = gomodcacheForEnv(goenv)
+	if r.moduleCacheDir == "" {
+		return nil, fmt.Errorf("cannot resolve GOMODCACHE")
 	}
 
 	sort.Slice(r.modsByModPath, func(i, j int) bool {
@@ -141,7 +178,11 @@ func (r *ModuleResolver) init() error {
 	} else {
 		addDep := func(mod *gocommand.ModuleJSON) {
 			if mod.Replace == nil {
-				// This is redundant with the cache, but we'll skip it cheaply enough.
+				// This is redundant with the cache, but we'll skip it cheaply enough
+				// when we encounter it in the module cache scan.
+				//
+				// Including it at a lower index in r.roots than the module cache dir
+				// helps prioritize matches from within existing dependencies.
 				r.roots = append(r.roots, gopathwalk.Root{Path: mod.Dir, Type: gopathwalk.RootModuleCache})
 			} else {
 				r.roots = append(r.roots, gopathwalk.Root{Path: mod.Dir, Type: gopathwalk.RootOther})
@@ -158,24 +199,40 @@ func (r *ModuleResolver) init() error {
 				addDep(mod)
 			}
 		}
+		// If provided, share the moduleCacheCache.
+		//
+		// TODO(rfindley): The module cache is immutable. However, the loaded
+		// exports do depend on GOOS and GOARCH. Fortunately, the
+		// ProcessEnv.buildContext does not adjust these from build.DefaultContext
+		// (even though it should). So for now, this is OK to share, but we need to
+		// add logic for handling GOOS/GOARCH.
+		r.moduleCacheCache = moduleCacheCache
 		r.roots = append(r.roots, gopathwalk.Root{Path: r.moduleCacheDir, Type: gopathwalk.RootModuleCache})
 	}
 
 	r.scannedRoots = map[gopathwalk.Root]bool{}
 	if r.moduleCacheCache == nil {
-		r.moduleCacheCache = &dirInfoCache{
-			dirs:      map[string]*directoryPackageInfo{},
-			listeners: map[*int]cacheListener{},
-		}
-	}
-	if r.otherCache == nil {
-		r.otherCache = &dirInfoCache{
-			dirs:      map[string]*directoryPackageInfo{},
-			listeners: map[*int]cacheListener{},
-		}
+		r.moduleCacheCache = NewDirInfoCache()
 	}
-	r.initialized = true
-	return nil
+	r.otherCache = NewDirInfoCache()
+	return r, nil
+}
+
+// gomodcacheForEnv returns the GOMODCACHE value to use based on the given env
+// map, which must have GOMODCACHE and GOPATH populated.
+//
+// TODO(rfindley): this is defensive refactoring.
+//  1. Is this even relevant anymore? Can't we just read GOMODCACHE.
+//  2. Use this to separate module cache scanning from other scanning.
+func gomodcacheForEnv(goenv map[string]string) string {
+	if gmc := goenv["GOMODCACHE"]; gmc != "" {
+		return gmc
+	}
+	gopaths := filepath.SplitList(goenv["GOPATH"])
+	if len(gopaths) == 0 {
+		return ""
+	}
+	return filepath.Join(gopaths[0], "/pkg/mod")
 }
 
 func (r *ModuleResolver) initAllMods() error {
@@ -206,30 +263,82 @@ func (r *ModuleResolver) initAllMods() error {
 	return nil
 }
 
-func (r *ModuleResolver) ClearForNewScan() {
-	<-r.scanSema
-	r.scannedRoots = map[gopathwalk.Root]bool{}
-	r.otherCache = &dirInfoCache{
-		dirs:      map[string]*directoryPackageInfo{},
-		listeners: map[*int]cacheListener{},
+// ClearForNewScan invalidates the last scan.
+//
+// It preserves the set of roots, but forgets about the set of directories.
+// Though it forgets the set of module cache directories, it remembers their
+// contents, since they are assumed to be immutable.
+func (r *ModuleResolver) ClearForNewScan() Resolver {
+	<-r.scanSema // acquire r, to guard scannedRoots
+	r2 := &ModuleResolver{
+		env:            r.env,
+		dummyVendorMod: r.dummyVendorMod,
+		moduleCacheDir: r.moduleCacheDir,
+		roots:          r.roots,
+		mains:          r.mains,
+		mainByDir:      r.mainByDir,
+		modsByModPath:  r.modsByModPath,
+
+		scanSema:         make(chan struct{}, 1),
+		scannedRoots:     make(map[gopathwalk.Root]bool),
+		otherCache:       NewDirInfoCache(),
+		moduleCacheCache: r.moduleCacheCache,
+	}
+	r2.scanSema <- struct{}{} // r2 must start released
+	// Invalidate root scans. We don't need to invalidate module cache roots,
+	// because they are immutable.
+	// (We don't support a use case where GOMODCACHE is cleaned in the middle of
+	// e.g. a gopls session: the user must restart gopls to get accurate
+	// imports.)
+	//
+	// Scanning for new directories in GOMODCACHE should be handled elsewhere,
+	// via a call to ScanModuleCache.
+	for _, root := range r.roots {
+		if root.Type == gopathwalk.RootModuleCache && r.scannedRoots[root] {
+			r2.scannedRoots[root] = true
+		}
 	}
-	r.scanSema <- struct{}{}
+	r.scanSema <- struct{}{} // release r
+	return r2
 }
 
-func (r *ModuleResolver) ClearForNewMod() {
-	<-r.scanSema
-	*r = ModuleResolver{
-		env:              r.env,
-		moduleCacheCache: r.moduleCacheCache,
-		otherCache:       r.otherCache,
-		scanSema:         r.scanSema,
+// ClearModuleInfo invalidates resolver state that depends on go.mod file
+// contents (essentially, the output of go list -m -json ...).
+//
+// Notably, it does not forget directory contents, which are reset
+// asynchronously via ClearForNewScan.
+//
+// If the ProcessEnv is a GOPATH environment, ClearModuleInfo is a no op.
+//
+// TODO(rfindley): move this to a new env.go, consolidating ProcessEnv methods.
+func (e *ProcessEnv) ClearModuleInfo() {
+	if r, ok := e.resolver.(*ModuleResolver); ok {
+		resolver, resolverErr := newModuleResolver(e, e.ModCache)
+		if resolverErr == nil {
+			<-r.scanSema // acquire (guards caches)
+			resolver.moduleCacheCache = r.moduleCacheCache
+			resolver.otherCache = r.otherCache
+			r.scanSema <- struct{}{} // release
+		}
+		e.resolver = resolver
+		e.resolverErr = resolverErr
 	}
-	r.init()
-	r.scanSema <- struct{}{}
 }
 
-// findPackage returns the module and directory that contains the package at
-// the given import path, or returns nil, "" if no module is in scope.
+// UpdateResolver sets the resolver for the ProcessEnv to use in imports
+// operations. Only for use with the result of [Resolver.ClearForNewScan].
+//
+// TODO(rfindley): this awkward API is a result of the (arguably) inverted
+// relationship between configuration and state described in the doc comment
+// for [ProcessEnv].
+func (e *ProcessEnv) UpdateResolver(r Resolver) {
+	e.resolver = r
+	e.resolverErr = nil
+}
+
+// findPackage returns the module and directory from within the main modules
+// and their dependencies that contains the package at the given import path,
+// or returns nil, "" if no module is in scope.
 func (r *ModuleResolver) findPackage(importPath string) (*gocommand.ModuleJSON, string) {
 	// This can't find packages in the stdlib, but that's harmless for all
 	// the existing code paths.
@@ -295,10 +404,6 @@ func (r *ModuleResolver) cacheStore(info directoryPackageInfo) {
 	}
 }
 
-func (r *ModuleResolver) cacheKeys() []string {
-	return append(r.moduleCacheCache.Keys(), r.otherCache.Keys()...)
-}
-
 // cachePackageName caches the package name for a dir already in the cache.
 func (r *ModuleResolver) cachePackageName(info directoryPackageInfo) (string, error) {
 	if info.rootType == gopathwalk.RootModuleCache {
@@ -367,15 +472,15 @@ func (r *ModuleResolver) dirIsNestedModule(dir string, mod *gocommand.ModuleJSON
 	return modDir != mod.Dir
 }
 
-func (r *ModuleResolver) modInfo(dir string) (modDir string, modName string) {
-	readModName := func(modFile string) string {
-		modBytes, err := os.ReadFile(modFile)
-		if err != nil {
-			return ""
-		}
-		return modulePath(modBytes)
+func readModName(modFile string) string {
+	modBytes, err := os.ReadFile(modFile)
+	if err != nil {
+		return ""
 	}
+	return modulePath(modBytes)
+}
 
+func (r *ModuleResolver) modInfo(dir string) (modDir, modName string) {
 	if r.dirInModuleCache(dir) {
 		if matches := modCacheRegexp.FindStringSubmatch(dir); len(matches) == 3 {
 			index := strings.Index(dir, matches[1]+"@"+matches[2])
@@ -409,11 +514,9 @@ func (r *ModuleResolver) dirInModuleCache(dir string) bool {
 }
 
 func (r *ModuleResolver) loadPackageNames(importPaths []string, srcDir string) (map[string]string, error) {
-	if err := r.init(); err != nil {
-		return nil, err
-	}
 	names := map[string]string{}
 	for _, path := range importPaths {
+		// TODO(rfindley): shouldn't this use the dirInfoCache?
 		_, packageDir := r.findPackage(path)
 		if packageDir == "" {
 			continue
@@ -431,10 +534,6 @@ func (r *ModuleResolver) scan(ctx context.Context, callback *scanCallback) error
 	ctx, done := event.Start(ctx, "imports.ModuleResolver.scan")
 	defer done()
 
-	if err := r.init(); err != nil {
-		return err
-	}
-
 	processDir := func(info directoryPackageInfo) {
 		// Skip this directory if we were not able to get the package information successfully.
 		if scanned, err := info.reachedStatus(directoryScanned); !scanned || err != nil {
@@ -444,18 +543,18 @@ func (r *ModuleResolver) scan(ctx context.Context, callback *scanCallback) error
 		if err != nil {
 			return
 		}
-
 		if !callback.dirFound(pkg) {
 			return
 		}
+
 		pkg.packageName, err = r.cachePackageName(info)
 		if err != nil {
 			return
 		}
-
 		if !callback.packageNameLoaded(pkg) {
 			return
 		}
+
 		_, exports, err := r.loadExports(ctx, pkg, false)
 		if err != nil {
 			return
@@ -494,7 +593,6 @@ func (r *ModuleResolver) scan(ctx context.Context, callback *scanCallback) error
 		return packageScanned
 	}
 
-	// Add anything new to the cache, and process it if we're still listening.
 	add := func(root gopathwalk.Root, dir string) {
 		r.cacheStore(r.scanDirForPackage(root, dir))
 	}
@@ -509,9 +607,9 @@ func (r *ModuleResolver) scan(ctx context.Context, callback *scanCallback) error
 		select {
 		case <-ctx.Done():
 			return
-		case <-r.scanSema:
+		case <-r.scanSema: // acquire
 		}
-		defer func() { r.scanSema <- struct{}{} }()
+		defer func() { r.scanSema <- struct{}{} }() // release
 		// We have the lock on r.scannedRoots, and no other scans can run.
 		for _, root := range roots {
 			if ctx.Err() != nil {
@@ -613,9 +711,6 @@ func (r *ModuleResolver) canonicalize(info directoryPackageInfo) (*pkg, error) {
 }
 
 func (r *ModuleResolver) loadExports(ctx context.Context, pkg *pkg, includeTest bool) (string, []string, error) {
-	if err := r.init(); err != nil {
-		return "", nil, err
-	}
 	if info, ok := r.cacheLoad(pkg.dir); ok && !includeTest {
 		return r.cacheExports(ctx, r.env, info)
 	}
diff --git a/vendor/golang.org/x/tools/internal/imports/mod_cache.go b/vendor/golang.org/x/tools/internal/imports/mod_cache.go
index 45690abbb..cfc546576 100644
--- a/vendor/golang.org/x/tools/internal/imports/mod_cache.go
+++ b/vendor/golang.org/x/tools/internal/imports/mod_cache.go
@@ -7,8 +7,12 @@ package imports
 import (
 	"context"
 	"fmt"
+	"path"
+	"path/filepath"
+	"strings"
 	"sync"
 
+	"golang.org/x/mod/module"
 	"golang.org/x/tools/internal/gopathwalk"
 )
 
@@ -39,6 +43,8 @@ const (
 	exportsLoaded
 )
 
+// directoryPackageInfo holds (possibly incomplete) information about packages
+// contained in a given directory.
 type directoryPackageInfo struct {
 	// status indicates the extent to which this struct has been filled in.
 	status directoryPackageStatus
@@ -63,7 +69,10 @@ type directoryPackageInfo struct {
 	packageName string // the package name, as declared in the source.
 
 	// Set when status >= exportsLoaded.
-
+	// TODO(rfindley): it's hard to see this, but exports depend implicitly on
+	// the default build context GOOS and GOARCH.
+	//
+	// We can make this explicit, and key exports by GOOS, GOARCH.
 	exports []string
 }
 
@@ -79,7 +88,7 @@ func (info *directoryPackageInfo) reachedStatus(target directoryPackageStatus) (
 	return true, nil
 }
 
-// dirInfoCache is a concurrency safe map for storing information about
+// DirInfoCache is a concurrency-safe map for storing information about
 // directories that may contain packages.
 //
 // The information in this cache is built incrementally. Entries are initialized in scan.
@@ -92,21 +101,26 @@ func (info *directoryPackageInfo) reachedStatus(target directoryPackageStatus) (
 // The information in the cache is not expected to change for the cache's
 // lifetime, so there is no protection against competing writes. Users should
 // take care not to hold the cache across changes to the underlying files.
-//
-// TODO(suzmue): consider other concurrency strategies and data structures (RWLocks, sync.Map, etc)
-type dirInfoCache struct {
+type DirInfoCache struct {
 	mu sync.Mutex
 	// dirs stores information about packages in directories, keyed by absolute path.
 	dirs      map[string]*directoryPackageInfo
 	listeners map[*int]cacheListener
 }
 
+func NewDirInfoCache() *DirInfoCache {
+	return &DirInfoCache{
+		dirs:      make(map[string]*directoryPackageInfo),
+		listeners: make(map[*int]cacheListener),
+	}
+}
+
 type cacheListener func(directoryPackageInfo)
 
 // ScanAndListen calls listener on all the items in the cache, and on anything
 // newly added. The returned stop function waits for all in-flight callbacks to
 // finish and blocks new ones.
-func (d *dirInfoCache) ScanAndListen(ctx context.Context, listener cacheListener) func() {
+func (d *DirInfoCache) ScanAndListen(ctx context.Context, listener cacheListener) func() {
 	ctx, cancel := context.WithCancel(ctx)
 
 	// Flushing out all the callbacks is tricky without knowing how many there
@@ -162,8 +176,10 @@ func (d *dirInfoCache) ScanAndListen(ctx context.Context, listener cacheListener
 }
 
 // Store stores the package info for dir.
-func (d *dirInfoCache) Store(dir string, info directoryPackageInfo) {
+func (d *DirInfoCache) Store(dir string, info directoryPackageInfo) {
 	d.mu.Lock()
+	// TODO(rfindley, golang/go#59216): should we overwrite an existing entry?
+	// That seems incorrect as the cache should be idempotent.
 	_, old := d.dirs[dir]
 	d.dirs[dir] = &info
 	var listeners []cacheListener
@@ -180,7 +196,7 @@ func (d *dirInfoCache) Store(dir string, info directoryPackageInfo) {
 }
 
 // Load returns a copy of the directoryPackageInfo for absolute directory dir.
-func (d *dirInfoCache) Load(dir string) (directoryPackageInfo, bool) {
+func (d *DirInfoCache) Load(dir string) (directoryPackageInfo, bool) {
 	d.mu.Lock()
 	defer d.mu.Unlock()
 	info, ok := d.dirs[dir]
@@ -191,7 +207,7 @@ func (d *dirInfoCache) Load(dir string) (directoryPackageInfo, bool) {
 }
 
 // Keys returns the keys currently present in d.
-func (d *dirInfoCache) Keys() (keys []string) {
+func (d *DirInfoCache) Keys() (keys []string) {
 	d.mu.Lock()
 	defer d.mu.Unlock()
 	for key := range d.dirs {
@@ -200,7 +216,7 @@ func (d *dirInfoCache) Keys() (keys []string) {
 	return keys
 }
 
-func (d *dirInfoCache) CachePackageName(info directoryPackageInfo) (string, error) {
+func (d *DirInfoCache) CachePackageName(info directoryPackageInfo) (string, error) {
 	if loaded, err := info.reachedStatus(nameLoaded); loaded {
 		return info.packageName, err
 	}
@@ -213,7 +229,7 @@ func (d *dirInfoCache) CachePackageName(info directoryPackageInfo) (string, erro
 	return info.packageName, info.err
 }
 
-func (d *dirInfoCache) CacheExports(ctx context.Context, env *ProcessEnv, info directoryPackageInfo) (string, []string, error) {
+func (d *DirInfoCache) CacheExports(ctx context.Context, env *ProcessEnv, info directoryPackageInfo) (string, []string, error) {
 	if reached, _ := info.reachedStatus(exportsLoaded); reached {
 		return info.packageName, info.exports, info.err
 	}
@@ -234,3 +250,81 @@ func (d *dirInfoCache) CacheExports(ctx context.Context, env *ProcessEnv, info d
 	d.Store(info.dir, info)
 	return info.packageName, info.exports, info.err
 }
+
+// ScanModuleCache walks the given directory, which must be a GOMODCACHE value,
+// for directory package information, storing the results in cache.
+func ScanModuleCache(dir string, cache *DirInfoCache, logf func(string, ...any)) {
+	// Note(rfindley): it's hard to see, but this function attempts to implement
+	// just the side effects on cache of calling PrimeCache with a ProcessEnv
+	// that has the given dir as its GOMODCACHE.
+	//
+	// Teasing out the control flow, we see that we can avoid any handling of
+	// vendor/ and can infer module info entirely from the path, simplifying the
+	// logic here.
+
+	root := gopathwalk.Root{
+		Path: filepath.Clean(dir),
+		Type: gopathwalk.RootModuleCache,
+	}
+
+	directoryInfo := func(root gopathwalk.Root, dir string) directoryPackageInfo {
+		// This is a copy of ModuleResolver.scanDirForPackage, trimmed down to
+		// logic that applies to a module cache directory.
+
+		subdir := ""
+		if dir != root.Path {
+			subdir = dir[len(root.Path)+len("/"):]
+		}
+
+		matches := modCacheRegexp.FindStringSubmatch(subdir)
+		if len(matches) == 0 {
+			return directoryPackageInfo{
+				status: directoryScanned,
+				err:    fmt.Errorf("invalid module cache path: %v", subdir),
+			}
+		}
+		modPath, err := module.UnescapePath(filepath.ToSlash(matches[1]))
+		if err != nil {
+			if logf != nil {
+				logf("decoding module cache path %q: %v", subdir, err)
+			}
+			return directoryPackageInfo{
+				status: directoryScanned,
+				err:    fmt.Errorf("decoding module cache path %q: %v", subdir, err),
+			}
+		}
+		importPath := path.Join(modPath, filepath.ToSlash(matches[3]))
+		index := strings.Index(dir, matches[1]+"@"+matches[2])
+		modDir := filepath.Join(dir[:index], matches[1]+"@"+matches[2])
+		modName := readModName(filepath.Join(modDir, "go.mod"))
+		return directoryPackageInfo{
+			status:                 directoryScanned,
+			dir:                    dir,
+			rootType:               root.Type,
+			nonCanonicalImportPath: importPath,
+			moduleDir:              modDir,
+			moduleName:             modName,
+		}
+	}
+
+	add := func(root gopathwalk.Root, dir string) {
+		info := directoryInfo(root, dir)
+		cache.Store(info.dir, info)
+	}
+
+	skip := func(_ gopathwalk.Root, dir string) bool {
+		// Skip directories that have already been scanned.
+		//
+		// Note that gopathwalk only adds "package" directories, which must contain
+		// a .go file, and all such package directories in the module cache are
+		// immutable. So if we can load a dir, it can be skipped.
+		info, ok := cache.Load(dir)
+		if !ok {
+			return false
+		}
+		packageScanned, _ := info.reachedStatus(directoryScanned)
+		return packageScanned
+	}
+
+	gopathwalk.WalkSkip([]gopathwalk.Root{root}, add, skip, gopathwalk.Options{Logf: logf, ModulesEnabled: true})
+}
diff --git a/vendor/golang.org/x/tools/internal/imports/zstdlib.go b/vendor/golang.org/x/tools/internal/imports/zstdlib.go
index 9f992c2be..8db24df2f 100644
--- a/vendor/golang.org/x/tools/internal/imports/zstdlib.go
+++ b/vendor/golang.org/x/tools/internal/imports/zstdlib.go
@@ -151,6 +151,7 @@ var stdlib = map[string][]string{
 	"cmp": {
 		"Compare",
 		"Less",
+		"Or",
 		"Ordered",
 	},
 	"compress/bzip2": {
@@ -632,6 +633,8 @@ var stdlib = map[string][]string{
 		"NameMismatch",
 		"NewCertPool",
 		"NotAuthorizedToSign",
+		"OID",
+		"OIDFromInts",
 		"PEMCipher",
 		"PEMCipher3DES",
 		"PEMCipherAES128",
@@ -706,6 +709,7 @@ var stdlib = map[string][]string{
 		"LevelWriteCommitted",
 		"Named",
 		"NamedArg",
+		"Null",
 		"NullBool",
 		"NullByte",
 		"NullFloat64",
@@ -1921,6 +1925,7 @@ var stdlib = map[string][]string{
 		"R_LARCH_32",
 		"R_LARCH_32_PCREL",
 		"R_LARCH_64",
+		"R_LARCH_64_PCREL",
 		"R_LARCH_ABS64_HI12",
 		"R_LARCH_ABS64_LO20",
 		"R_LARCH_ABS_HI20",
@@ -1928,12 +1933,17 @@ var stdlib = map[string][]string{
 		"R_LARCH_ADD16",
 		"R_LARCH_ADD24",
 		"R_LARCH_ADD32",
+		"R_LARCH_ADD6",
 		"R_LARCH_ADD64",
 		"R_LARCH_ADD8",
+		"R_LARCH_ADD_ULEB128",
+		"R_LARCH_ALIGN",
 		"R_LARCH_B16",
 		"R_LARCH_B21",
 		"R_LARCH_B26",
+		"R_LARCH_CFA",
 		"R_LARCH_COPY",
+		"R_LARCH_DELETE",
 		"R_LARCH_GNU_VTENTRY",
 		"R_LARCH_GNU_VTINHERIT",
 		"R_LARCH_GOT64_HI12",
@@ -1953,6 +1963,7 @@ var stdlib = map[string][]string{
 		"R_LARCH_PCALA64_LO20",
 		"R_LARCH_PCALA_HI20",
 		"R_LARCH_PCALA_LO12",
+		"R_LARCH_PCREL20_S2",
 		"R_LARCH_RELATIVE",
 		"R_LARCH_RELAX",
 		"R_LARCH_SOP_ADD",
@@ -1983,8 +1994,10 @@ var stdlib = map[string][]string{
 		"R_LARCH_SUB16",
 		"R_LARCH_SUB24",
 		"R_LARCH_SUB32",
+		"R_LARCH_SUB6",
 		"R_LARCH_SUB64",
 		"R_LARCH_SUB8",
+		"R_LARCH_SUB_ULEB128",
 		"R_LARCH_TLS_DTPMOD32",
 		"R_LARCH_TLS_DTPMOD64",
 		"R_LARCH_TLS_DTPREL32",
@@ -2035,6 +2048,7 @@ var stdlib = map[string][]string{
 		"R_MIPS_LO16",
 		"R_MIPS_NONE",
 		"R_MIPS_PC16",
+		"R_MIPS_PC32",
 		"R_MIPS_PJUMP",
 		"R_MIPS_REL16",
 		"R_MIPS_REL32",
@@ -2952,6 +2966,8 @@ var stdlib = map[string][]string{
 		"RegisterName",
 	},
 	"encoding/hex": {
+		"AppendDecode",
+		"AppendEncode",
 		"Decode",
 		"DecodeString",
 		"DecodedLen",
@@ -3233,6 +3249,7 @@ var stdlib = map[string][]string{
 		"TypeSpec",
 		"TypeSwitchStmt",
 		"UnaryExpr",
+		"Unparen",
 		"ValueSpec",
 		"Var",
 		"Visitor",
@@ -3492,6 +3509,7 @@ var stdlib = map[string][]string{
 		"XOR_ASSIGN",
 	},
 	"go/types": {
+		"Alias",
 		"ArgumentError",
 		"Array",
 		"AssertableTo",
@@ -3559,6 +3577,7 @@ var stdlib = map[string][]string{
 		"MethodVal",
 		"MissingMethod",
 		"Named",
+		"NewAlias",
 		"NewArray",
 		"NewChan",
 		"NewChecker",
@@ -3627,6 +3646,7 @@ var stdlib = map[string][]string{
 		"Uint64",
 		"Uint8",
 		"Uintptr",
+		"Unalias",
 		"Union",
 		"Universe",
 		"Unsafe",
@@ -3643,6 +3663,11 @@ var stdlib = map[string][]string{
 		"WriteSignature",
 		"WriteType",
 	},
+	"go/version": {
+		"Compare",
+		"IsValid",
+		"Lang",
+	},
 	"hash": {
 		"Hash",
 		"Hash32",
@@ -4078,6 +4103,7 @@ var stdlib = map[string][]string{
 		"NewTextHandler",
 		"Record",
 		"SetDefault",
+		"SetLogLoggerLevel",
 		"Source",
 		"SourceKey",
 		"String",
@@ -4367,6 +4393,35 @@ var stdlib = map[string][]string{
 		"Uint64",
 		"Zipf",
 	},
+	"math/rand/v2": {
+		"ChaCha8",
+		"ExpFloat64",
+		"Float32",
+		"Float64",
+		"Int",
+		"Int32",
+		"Int32N",
+		"Int64",
+		"Int64N",
+		"IntN",
+		"N",
+		"New",
+		"NewChaCha8",
+		"NewPCG",
+		"NewZipf",
+		"NormFloat64",
+		"PCG",
+		"Perm",
+		"Rand",
+		"Shuffle",
+		"Source",
+		"Uint32",
+		"Uint32N",
+		"Uint64",
+		"Uint64N",
+		"UintN",
+		"Zipf",
+	},
 	"mime": {
 		"AddExtensionType",
 		"BEncoding",
@@ -4540,6 +4595,7 @@ var stdlib = map[string][]string{
 		"FS",
 		"File",
 		"FileServer",
+		"FileServerFS",
 		"FileSystem",
 		"Flusher",
 		"Get",
@@ -4566,6 +4622,7 @@ var stdlib = map[string][]string{
 		"MethodPut",
 		"MethodTrace",
 		"NewFileTransport",
+		"NewFileTransportFS",
 		"NewRequest",
 		"NewRequestWithContext",
 		"NewResponseController",
@@ -4599,6 +4656,7 @@ var stdlib = map[string][]string{
 		"Serve",
 		"ServeContent",
 		"ServeFile",
+		"ServeFileFS",
 		"ServeMux",
 		"ServeTLS",
 		"Server",
@@ -5106,6 +5164,7 @@ var stdlib = map[string][]string{
 		"StructTag",
 		"Swapper",
 		"Type",
+		"TypeFor",
 		"TypeOf",
 		"Uint",
 		"Uint16",
@@ -5342,6 +5401,7 @@ var stdlib = map[string][]string{
 		"CompactFunc",
 		"Compare",
 		"CompareFunc",
+		"Concat",
 		"Contains",
 		"ContainsFunc",
 		"Delete",
@@ -10824,6 +10884,7 @@ var stdlib = map[string][]string{
 		"Value",
 	},
 	"testing/slogtest": {
+		"Run",
 		"TestHandler",
 	},
 	"text/scanner": {