cmd/go: report which patterns match each package in list

It's important for some uses of go/packages, as well as for some
of go/packages's internal use, to be able to tell which results from
go list output correspond to which patterns, keeping in mind that
a single package might have been matched by multiple patterns.

Also adds test for #26925.

Change-Id: I708ac162f65d9946fe6afb244b08dc7b04d2b530
Reviewed-on: https://go-review.googlesource.com/129060
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>

4 files changed, 56 insertions, 66 deletions

diff --git a/src/cmd/go/internal/list/list.go b/src/cmd/go/internal/list/list.go
index 423516aad7..186b006c12 100644
--- a/src/cmd/go/internal/list/list.go
+++ b/src/cmd/go/internal/list/list.go
@@ -47,24 +47,25 @@ syntax of package template. The default output is equivalent
 to -f '{{.ImportPath}}'. The struct being passed to the template is:
 
     type Package struct {
-        Dir           string  // directory containing package sources
-        ImportPath    string  // import path of package in dir
-        ImportComment string  // path in import comment on package statement
-        Name          string  // package name
-        Doc           string  // package documentation string
-        Target        string  // install path
-        Shlib         string  // the shared library that contains this package (only set when -linkshared)
-        Goroot        bool    // is this package in the Go root?
-        Standard      bool    // is this package part of the standard Go library?
-        Stale         bool    // would 'go install' do anything for this package?
-        StaleReason   string  // explanation for Stale==true
-        Root          string  // Go root or Go path dir containing this package
-        ConflictDir   string  // this directory shadows Dir in $GOPATH
-        BinaryOnly    bool    // binary-only package: cannot be recompiled from sources
-        ForTest       string  // package is only for use in named test
-        DepOnly       bool    // package is only a dependency, not explicitly listed
-        Export        string  // file containing export data (when using -export)
-        Module        *Module // info about package's containing module, if any (can be nil)
+        Dir           string   // directory containing package sources
+        ImportPath    string   // import path of package in dir
+        ImportComment string   // path in import comment on package statement
+        Name          string   // package name
+        Doc           string   // package documentation string
+        Target        string   // install path
+        Shlib         string   // the shared library that contains this package (only set when -linkshared)
+        Goroot        bool     // is this package in the Go root?
+        Standard      bool     // is this package part of the standard Go library?
+        Stale         bool     // would 'go install' do anything for this package?
+        StaleReason   string   // explanation for Stale==true
+        Root          string   // Go root or Go path dir containing this package
+        ConflictDir   string   // this directory shadows Dir in $GOPATH
+        BinaryOnly    bool     // binary-only package: cannot be recompiled from sources
+        ForTest       string   // package is only for use in named test
+        Export        string   // file containing export data (when using -export)
+        Module        *Module  // info about package's containing module, if any (can be nil)
+        Match         []string // command-line patterns matching this package
+        DepOnly       bool     // package is only a dependency, not explicitly listed
 
         // Source files
         GoFiles         []string // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
diff --git a/src/cmd/go/internal/load/pkg.go b/src/cmd/go/internal/load/pkg.go
index b7257e77e3..43887b0008 100644
--- a/src/cmd/go/internal/load/pkg.go
+++ b/src/cmd/go/internal/load/pkg.go
@@ -60,15 +60,17 @@ type PackagePublic struct {
 	Doc           string                `json:",omitempty"` // package documentation string
 	Target        string                `json:",omitempty"` // installed target for this package (may be executable)
 	Shlib         string                `json:",omitempty"` // the shared library that contains this package (only set when -linkshared)
-	Goroot        bool                  `json:",omitempty"` // is this package found in the Go root?
-	Standard      bool                  `json:",omitempty"` // is this package part of the standard Go library?
 	Root          string                `json:",omitempty"` // Go root or Go path dir containing this package
 	ConflictDir   string                `json:",omitempty"` // Dir is hidden by this other directory
-	BinaryOnly    bool                  `json:",omitempty"` // package cannot be recompiled
 	ForTest       string                `json:",omitempty"` // package is only for use in named test
-	DepOnly       bool                  `json:",omitempty"` // package is only as a dependency, not explicitly listed
 	Export        string                `json:",omitempty"` // file containing export data (set by go list -export)
 	Module        *modinfo.ModulePublic `json:",omitempty"` // info about package's module, if any
+	Match         []string              `json:",omitempty"` // command-line patterns matching this package
+	Goroot        bool                  `json:",omitempty"` // is this package found in the Go root?
+	Standard      bool                  `json:",omitempty"` // is this package part of the standard Go library?
+	DepOnly       bool                  `json:",omitempty"` // package is only as a dependency, not explicitly listed
+	BinaryOnly    bool                  `json:",omitempty"` // package cannot be recompiled
+	Incomplete    bool                  `json:",omitempty"` // was there an error loading this package or dependencies?
 
 	// Stale and StaleReason remain here *only* for the list command.
 	// They are only initialized in preparation for list execution.
@@ -107,7 +109,7 @@ type PackagePublic struct {
 	Deps      []string          `json:",omitempty"` // all (recursively) imported dependencies
 
 	// Error information
-	Incomplete bool            `json:",omitempty"` // was there an error loading this package or dependencies?
+	// Incomplete is above, packed into the other bools
 	Error      *PackageError   `json:",omitempty"` // error loading this package (not dependencies)
 	DepsErrors []*PackageError `json:",omitempty"` // errors loading dependencies
 
@@ -1848,6 +1850,7 @@ func PackagesAndErrors(patterns []string) []*Package {
 	for _, m := range matches {
 		for _, pkg := range m.Pkgs {
 			p := loadPackage(pkg, &stk)
+			p.Match = append(p.Match, m.Pattern)
 			p.Internal.CmdlinePkg = true
 			if m.Literal {
 				// Note: do not set = m.Literal unconditionally
@@ -1937,7 +1940,6 @@ func PackagesForBuild(args []string) []*Package {
 func GoFilesPackage(gofiles []string) *Package {
 	ModInit()
 
-	// TODO: Remove this restriction.
 	for _, f := range gofiles {
 		if !strings.HasSuffix(f, ".go") {
 			base.Fatalf("named files must be .go files")
@@ -1998,6 +2000,7 @@ func GoFilesPackage(gofiles []string) *Package {
 	pkg.Internal.LocalPrefix = dirToImportPath(dir)
 	pkg.ImportPath = "command-line-arguments"
 	pkg.Target = ""
+	pkg.Match = gofiles
 
 	if pkg.Name == "main" {
 		_, elem := filepath.Split(gofiles[0])
diff --git a/src/cmd/go/internal/modload/load.go b/src/cmd/go/internal/modload/load.go
index e408e478d3..b00f81458f 100644
--- a/src/cmd/go/internal/modload/load.go
+++ b/src/cmd/go/internal/modload/load.go
@@ -56,14 +56,14 @@ func ImportPaths(patterns []string) []*search.Match {
 
 	var matches []*search.Match
 	for _, pattern := range search.CleanPatterns(patterns) {
-			m := &search.Match{
-				Pattern: pattern,
-				Literal: !strings.Contains(pattern, "...") && !search.IsMetaPackage(pattern),
-			}
-			if m.Literal {
-				m.Pkgs = []string{pattern}
-			}
-			matches = append(matches, m)
+		m := &search.Match{
+			Pattern: pattern,
+			Literal: !strings.Contains(pattern, "...") && !search.IsMetaPackage(pattern),
+		}
+		if m.Literal {
+			m.Pkgs = []string{pattern}
+		}
+		matches = append(matches, m)
 	}
 
 	fsDirs := make([][]string, len(matches))
@@ -622,7 +622,6 @@ func (ld *loader) computePatternAll(paths []string) []string {
 	}
 	sort.Strings(all)
 
-	fmt.Fprintf(os.Stderr, "ALL %v -> %v\n", paths, all)
 	return all
 }
 
diff --git a/src/cmd/go/testdata/script/mod_patterns.txt b/src/cmd/go/testdata/script/mod_patterns.txt
index a43fe82489..4fa436ba2d 100644
--- a/src/cmd/go/testdata/script/mod_patterns.txt
+++ b/src/cmd/go/testdata/script/mod_patterns.txt
@@ -5,43 +5,30 @@ cd m
 # 'go list all' should list all of the packages used (directly or indirectly) by
 # the packages in the main module, but no other packages from the standard
 # library or active modules.
-go list all
-stdout example.com/m/useunicode
-stdout example.com/m/useunsafe
-[cgo] stdout example.com/m/useC
-[!cgo] ! stdout example.com/m/useC
-stdout '^unicode$'
-stdout '^unsafe$'
-! stdout index/suffixarray
-
+#
 # 'go list ...' should list packages in all active modules and the standard library.
 # But not cmd/* - see golang.org/issue/26924.
-go list ...
-stdout example.com/unused/useerrors
-stdout example.com/m/useunsafe
-[cgo] stdout example.com/m/useC
-[!cgo] ! stdout example.com/m/useC
-stdout '^unicode$'
-stdout '^unsafe$'
-stdout index/suffixarray
-! stdout cmd/pprof
-
-# 'go list example.com/m/...' should list packages in all modules that begin with
-# "example.com/m/".
-go list example.com/m/...
-stdout example.com/m/useunicode
-stdout example.com/m/useunsafe
-! stdout example.com/[^m]
-! stdout ^[^e]
-[cgo] stdout example.com/m/useC
-[!cgo] ! stdout example.com/m/useC
-
+#
+# 'go list example.com/m/...' should list packages in all modules that begin with 'example.com/m/'.
+#
 # 'go list ./...' should list only packages in the current module, not other active modules.
-go list ./...
-stdout example.com/m/useunicode
-stdout example.com/m/useunsafe
-[cgo] stdout example.com/m/useC
+#
+# Warnings about unmatched patterns should only be printed once.
+#
+# And the go command should be able to keep track of all this!
+go list -f '{{.ImportPath}}: {{.Match}}' all ... example.com/m/... ./... ./xyz...
+stdout 'example.com/m/useunicode: \[all \.\.\. example.com/m/... ./...\]'
+stdout 'example.com/m/useunsafe: \[all \.\.\. example.com/m/... ./...\]'
+[cgo] stdout 'example.com/m/useC: \[all \.\.\. example.com/m/... ./...\]'
 [!cgo] ! stdout example.com/m/useC
+stdout 'example.com/unused/useerrors: \[\.\.\.\]' # but not "all"
+stdout 'example.com/m/nested/useencoding: \[\.\.\. example.com/m/...\]' # but NOT "all" or "./..."
+stdout '^unicode: \[all \.\.\.\]'
+stdout '^unsafe: \[all \.\.\.\]'
+stdout 'index/suffixarray: \[\.\.\.\]'
+! stdout cmd/pprof # golang.org/issue/26924
+
+stderr -count=1 '^go: warning: "./xyz..." matched no packages$'
 
 env CGO_ENABLED=0
 go list -f '{{.ImportPath}}: {{.Match}}' all ... example.com/m/... ./... ./xyz...