cmd/compile: simplify fingerprint logic

Historically, we sometimes recorded imports based on either package
path ("net/http") or object file path ("net/http.a"). But modern Go
build systems always use package path, and the extra ".a" suffix
doesn't mean anything anyway.

Change-Id: I6060ef8bafa324168710d152a353f4d8db062133
Reviewed-on: https://go-review.googlesource.com/c/go/+/395254
Trust: Matthew Dempsky <[email protected]>
Run-TryBot: Matthew Dempsky <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>

src/cmd/compile/internal/noder/import.go

@@ -369,16 +369,8 @@ func addFingerprint(path string, f *os.File, end int64) error {
  }
 
  copy(fingerprint[:], buf[:])
+ base.Ctxt.AddImport(path, fingerprint)
 
- // assume files move (get installed) so don't record the full path
- if base.Flag.Cfg.PackageFile != nil {
- // If using a packageFile map, assume path_ can be recorded directly.
- base.Ctxt.AddImport(path, fingerprint)
- } else {
- // For file "/Users/foo/go/pkg/darwin_amd64/math.a" record "math.a".
- file := f.Name()
- base.Ctxt.AddImport(file[len(file)-len(path)-len(".a"):], fingerprint)
- }
  return nil
 }
 

src/cmd/link/internal/ld/ld.go

@@ -96,19 +96,7 @@ func (ctxt *Link) readImportCfg(file string) {
 }
 
 func pkgname(ctxt *Link, lib string) string {
- name := path.Clean(lib)
-
- // When using importcfg, we have the final package name.
- if ctxt.PackageFile != nil {
- return name
- }
-
- // runtime.a -> runtime, runtime.6 -> runtime
- pkg := name
- if len(pkg) >= 2 && pkg[len(pkg)-2] == '.' {
- pkg = pkg[:len(pkg)-2]
- }
- return pkg
+ return path.Clean(lib)
 }
 
 func findlib(ctxt *Link, lib string) (string, bool) {
@@ -127,34 +115,25 @@ func findlib(ctxt *Link, lib string) (string, bool) {
  return "", false
  }
  } else {
- if filepath.IsAbs(name) {
- pname = name
- } else {
- pkg := pkgname(ctxt, lib)
- // Add .a if needed; the new -importcfg modes
- // do not put .a into the package name anymore.
- // This only matters when people try to mix
- // compiles using -importcfg with links not using -importcfg,
- // such as when running quick things like
- // 'go tool compile x.go && go tool link x.o'
- // by hand against a standard library built using -importcfg.
- if !strings.HasSuffix(name, ".a") && !strings.HasSuffix(name, ".o") {
- name += ".a"
- }
- // try dot, -L "libdir", and then goroot.
- for _, dir := range ctxt.Libdir {
- if ctxt.linkShared {
- pname = filepath.Join(dir, pkg+".shlibname")
- if _, err := os.Stat(pname); err == nil {
- isshlib = true
- break
- }
- }
- pname = filepath.Join(dir, name)
+ pkg := pkgname(ctxt, lib)
+
+ // search -L "libdir" directories
+ for _, dir := range ctxt.Libdir {
+ if ctxt.linkShared {
+ pname = filepath.Join(dir, pkg+".shlibname")
  if _, err := os.Stat(pname); err == nil {
+ isshlib = true
  break
  }
  }
+ pname = filepath.Join(dir, name+".a")
+ if _, err := os.Stat(pname); err == nil {
+ break
+ }
+ pname = filepath.Join(dir, name+".o")
+ if _, err := os.Stat(pname); err == nil {
+ break
+ }
  }
  pname = filepath.Clean(pname)
  }

test/fixedbugs/bug369.go

@@ -1,4 +1,4 @@
-// +build !nacl,!js,!windows,gc
+// +build !nacl,!js,gc
 // run
 
 // Copyright 2011 The Go Authors. All rights reserved.
@@ -29,10 +29,12 @@ func main() {
  return filepath.Join(tmpDir, name)
  }
 
- run("go", "tool", "compile", "-p=pkg", "-N", "-o", tmp("slow.o"), "pkg.go")
- run("go", "tool", "compile", "-p=pkg", "-o", tmp("fast.o"), "pkg.go")
- run("go", "tool", "compile", "-p=main", "-D", tmpDir, "-o", tmp("main.o"), "main.go")
- run("go", "tool", "link", "-o", tmp("a.exe"), tmp("main.o"))
+ check(os.Mkdir(tmp("test"), 0777))
+
+ run("go", "tool", "compile", "-p=test/slow", "-N", "-o", tmp("test/slow.o"), "pkg.go")
+ run("go", "tool", "compile", "-p=test/fast", "-o", tmp("test/fast.o"), "pkg.go")
+ run("go", "tool", "compile", "-p=main", "-D", "test", "-I", tmpDir, "-o", tmp("main.o"), "main.go")
+ run("go", "tool", "link", "-L", tmpDir, "-o", tmp("a.exe"), tmp("main.o"))
  run(tmp("a.exe"))
 }