cmd/go/internal/modload: inline doImport into doPkg

doImport is itself a thin wrapper around Import, and doPkg is its only call
site. I'm having trouble following what doPkg is doing due to the indirection,
so I'm removing it.

Change-Id: I6167be68e869a36010a56a5869df50b1145ac813
Reviewed-on: https://go-review.googlesource.com/125837
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

src/cmd/go/internal/modload/load.go

@@ -494,7 +494,17 @@ func (ld *loader) doPkg(item interface{}) {
 		pkg.mod = pkg.testOf.mod
 		imports = pkg.testOf.testImports
 	} else {
-		pkg.mod, pkg.dir, pkg.err = ld.doImport(pkg.path)
+		if strings.Contains(pkg.path, "@") {
+			// Leave for error during load.
+			return
+		}
+		if build.IsLocalImport(pkg.path) {
+			// Leave for error during load.
+			// (Module mode does not allow local imports.)
+			return
+		}
+
+		pkg.mod, pkg.dir, pkg.err = Import(pkg.path)
 		if pkg.dir == "" {
 			return
 		}
@@ -526,26 +536,6 @@ func (ld *loader) doPkg(item interface{}) {
 	}
 }
 
-// doImport finds the directory holding source code for the given import path.
-// It returns the module containing the package (if any),
-// the directory containing the package (if any),
-// and any error encountered.
-// Not all packages have modules: the ones in the standard library do not.
-// Not all packages have directories: "unsafe" and "C" do not.
-func (ld *loader) doImport(path string) (mod module.Version, dir string, err error) {
-	if strings.Contains(path, "@") {
-		// Leave for error during load.
-		return module.Version{}, "", nil
-	}
-	if build.IsLocalImport(path) {
-		// Leave for error during load.
-		// (Module mode does not allow local imports.)
-		return module.Version{}, "", nil
-	}
-
-	return Import(path)
-}
-
 // scanDir is like imports.ScanDir but elides known magic imports from the list,
 // so that we do not go looking for packages that don't really exist.
 //