cmd/go: derive executable name from package path in 'go run'

Change name of temporary executable on go run . to directory name.
Fixes #31571

Change-Id: I0a0ce74154e76205bb43805c95bd7fb8fd2dfd01
GitHub-Last-Rev: e0964983e18a1d45b55f7098c7489059708c7e5e
GitHub-Pull-Request: golang/go#31614
Reviewed-on: https://go-review.googlesource.com/c/go/+/173297
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

src/cmd/go/internal/run/run.go

@@ -8,6 +8,7 @@ package run
 import (
 	"fmt"
 	"os"
+	"path"
 	"strings"
 
 	"cmd/go/internal/base"
@@ -94,10 +95,10 @@ func runRun(cmd *base.Command, args []string) {
 		base.Fatalf("go run: no go files listed")
 	}
 	cmdArgs := args[i:]
-
 	if p.Error != nil {
 		base.Fatalf("%s", p.Error)
 	}
+
 	p.Internal.OmitDebug = true
 	if len(p.DepsErrors) > 0 {
 		// Since these are errors in dependencies,
@@ -117,6 +118,8 @@ func runRun(cmd *base.Command, args []string) {
 		base.Fatalf("go run: cannot run non-main package")
 	}
 	p.Target = "" // must build - not up to date
+	if p.Internal.CmdlineFiles {
+		//set executable name if go file is given as cmd-argument
 		var src string
 		if len(p.GoFiles) > 0 {
 			src = p.GoFiles[0]
@@ -131,7 +134,10 @@ func runRun(cmd *base.Command, args []string) {
 			}
 			base.Fatalf("go run: no suitable source files%s", hint)
 		}
-	p.Internal.ExeName = src[:len(src)-len(".go")] // name temporary executable for first go file
+		p.Internal.ExeName = src[:len(src)-len(".go")]
+	} else {
+		p.Internal.ExeName = path.Base(p.ImportPath)
+	}
 	a1 := b.LinkAction(work.ModeBuild, work.ModeBuild, p)
 	a := &work.Action{Mode: "go run", Func: buildRunProgram, Args: cmdArgs, Deps: []*work.Action{a1}}
 	b.Do(a)

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

+env GO111MODULE=on
+# Check for correct naming of temporary executable
+
+#Test for single file specified
+cd x/y/z
+go run foo.go
+stderr 'foo'
+
+#Test for current directory
+go run .
+stderr 'z'
+
+#Test for set path
+go run m/x/y/z/
+stderr 'z'
+
+-- m/x/y/z/foo.go --
+package main
+import(
+	"os"
+	"path/filepath"
+)
+func main() {
+	println(filepath.Base(os.Args[0]))
+}
+
+-- x/y/z/foo.go --
+package main
+import(
+	"os"
+	"path/filepath"
+)
+func main() {
+	println(filepath.Base(os.Args[0]))
+}
+
+-- x/y/z/foo.go --
+package main
+import(
+	"os"
+	"path/filepath"
+)
+func main() {
+	println(filepath.Base(os.Args[0]))
+}
+
+-- go.mod --
+module m
\ No newline at end of file