cmd/go: add -u=patch option for go list

Fixes golang#41006

Change-Id: I52fb3a9525ccdacd9d4ed237ce62193c5f9c1551

Author: jeanbza

src/cmd/go/internal/list/list.go

@@ -337,6 +337,30 @@ func init() {
 	CmdList.Run = runList // break init cycle
 	work.AddBuildFlags(CmdList, work.DefaultBuildFlags)
 	CmdList.Flag.Var(&listJsonFields, "json", "")
+	CmdList.Flag.Var(&listU, "u", "")
+}
+
+// listUFlag is provided to maintain backwards compatibility with the old
+// bool-only behavior. Now that the -u flag supports a string (-u=patch), we
+// need to differentiate between non-existence, existence without value (-u),
+// and existence with value (-u=patch).
+type listUFlag struct {
+	set   bool
+	value string
+}
+
+func (f *listUFlag) Set(x string) error {
+	f.value = x
+	f.set = true
+	return nil
+}
+
+func (f *listUFlag) String() string {
+	return f.value
+}
+
+func (f *listUFlag) IsBoolFlag() bool {
+	return true
 }
 
 var (
@@ -352,7 +376,7 @@ var (
 	listRetracted  = CmdList.Flag.Bool("retracted", false, "")
 	listReuse      = CmdList.Flag.String("reuse", "", "")
 	listTest       = CmdList.Flag.Bool("test", false, "")
-	listU          = CmdList.Flag.Bool("u", false, "")
+	listU          listUFlag
 	listVersions   = CmdList.Flag.Bool("versions", false, "")
 )
 
@@ -522,7 +546,7 @@ func runList(ctx context.Context, cmd *base.Command, args []string) {
 			if *listVersions {
 				base.Fatalf(actionDisabledFormat, "determine available versions")
 			}
-			if *listU {
+			if listU.set {
 				base.Fatalf(actionDisabledFormat, "determine available upgrades")
 			}
 
@@ -540,7 +564,9 @@ func runList(ctx context.Context, cmd *base.Command, args []string) {
 		}
 
 		var mode modload.ListMode
-		if *listU {
+		if listU.value == "patch" {
+			mode |= modload.ListPatch | modload.ListRetracted | modload.ListDeprecated
+		} else if listU.set {
 			mode |= modload.ListU | modload.ListRetracted | modload.ListDeprecated
 		}
 		if *listRetracted {
@@ -574,7 +600,7 @@ func runList(ctx context.Context, cmd *base.Command, args []string) {
 	}
 
 	// Package mode (not -m).
-	if *listU {
+	if listU.set {
 		base.Fatalf("go list -u can only be used with -m")
 	}
 	if *listVersions {

src/cmd/go/internal/modload/build.go

@@ -124,12 +124,17 @@ func ModuleInfo(ctx context.Context, path string) *modinfo.ModulePublic {
 }
 
 // addUpdate fills in m.Update if an updated version is available.
-func addUpdate(ctx context.Context, m *modinfo.ModulePublic) {
+func addUpdate(ctx context.Context, m *modinfo.ModulePublic, minor bool) {
 	if m.Version == "" {
 		return
 	}
 
-	info, err := Query(ctx, m.Path, "upgrade", m.Version, CheckAllowed)
+	query := "upgrade"
+	if !minor {
+		query = "patch"
+	}
+
+	info, err := Query(ctx, m.Path, query, m.Version, CheckAllowed)
 	var noVersionErr *NoMatchingVersionError
 	if errors.Is(err, ErrDisallowed) ||
 		errors.Is(err, fs.ErrNotExist) ||

src/cmd/go/internal/modload/list.go

@@ -32,6 +32,7 @@ const (
 	ListDeprecated
 	ListVersions
 	ListRetractedVersions
+	ListPatch
 )
 
 // ListModules returns a description of the modules matching args, if known,
@@ -80,7 +81,9 @@ func ListModules(ctx context.Context, args []string, mode ListMode, reuseFile st
 				sem <- token{}
 				go func() {
 					if mode&ListU != 0 {
-						addUpdate(ctx, m)
+						addUpdate(ctx, m, true)
+					} else if mode&ListPatch != 0 {
+						addUpdate(ctx, m, false)
 					}
 					if mode&ListVersions != 0 {
 						addVersions(ctx, m, mode&ListRetractedVersions != 0)

src/cmd/go/testdata/script/mod_upgrade.txt

@@ -0,0 +1,61 @@
+# • listing -u=patch for a module that is already above the “latest” version
+# how... would that happen? o.O maybe a locally-tagged module? but not sure how i'd set that up in these tests? 
+#
+# DONE: • listing -u=patch for a module that is already at exactly the latest patch release
+# 
+# • listing -u=patch for a module one hop away from the main module (e.g. a 
+# dependency used by the test of an external package imported by the main module)
+# 
+# • listing -u=patch for a module that is not currently in the build list at all
+# 
+# • listing -u=patch, without -m (so listing packages instead of modules), with a 
+# -f argument that inspects {{.Module.Update.Version}}. (I believe that such an 
+# invocation should currently fail with go list -u can only be used with -m, which 
+# is fine, but we should have a test of it anyway — if only to remind us to update 
+# the test if we ever change that behavior.)
+
+
+env GO111MODULE=on
+
+# When -u is specified, show upgrades up to latest minor.patch.
+go list -u -m all
+stdout '^rsc.io/quote v1.2.0 \[v1.5.2\]$'
+
+# When -u=patch is specified, show upgrades up to latest patch.
+go list -u=patch -m all
+stdout '^rsc.io/quote v1.2.0 \[v1.2.1\]$'
+
+# When -u=patch is specified but the module is already at the latest patch,
+# don't show an upgrade option.
+go mod edit -require=rsc.io/quote v1.2.1
+go mod download rsc.io/quote
+go list -u patch -m all
+stdout '^rsc.io/quote v1.2.0$'
+
+# When -u is specified, show minor.patch upgrades for adjacent modules too.
+# (we are going to cloud.google.com/go/compute by way of golang.org/x/oauth2)
+go list -u -m all
+stdout '^cloud.google.com/go/compute v1.7.0 \[v1.10.0\]$'
+
+# When -u=patch is specified, show patch upgrades for adjacent modules too.
+# (we are going to cloud.google.com/go/compute by way of golang.org/x/oauth2)
+go list -u=patch -m all
+stdout '^cloud.google.com/go/compute v1.7.0$'
+
+-- go.mod --
+module x
+require (
+    rsc.io/quote v1.2.0
+    golang.org/x/oauth2 v0.0.0-20220909003341-f21342109be1
+)
+
+-- go.sum --
+rsc.io/quote v1.2.0 h1:fFMCNi0A97hfNrtUZVQKETbuc3h7bmfFQHnjutpPYCg=
+rsc.io/quote v1.2.0/go.mod h1:v83Ri/njykPcgJltBc/gEkJTmjTsNgtO1Y7vyIK1CQA=
+golang.org/x/oauth2 v0.0.0-20220909003341-f21342109be1 h1:lxqLZaMad/dJHMFZH0NiNpiEZI/nhgWhe4wgzpE+MuA=
+golang.org/x/oauth2 v0.0.0-20220909003341-f21342109be1/go.mod h1:h4gKUeWbJ4rQPri7E0u6Gs4e9Ri2zaLxzw5DI5XGrYg=
+-- use.go --
+package use
+
+import _ "rsc.io/quote"
+import _ "golang.org/x/oauth2"