Emit nogo facts into a separate archive (#3789)

* Use `-linkobj` to directly generate `.x` and `.a`

* Extract nogo facts into a separate file

* Address review comments

go/private/actions/archive.bzl

@@ -58,9 +58,13 @@ def emit_archive(go, source = None, _recompile_suffix = "", recompile_internal_d
         pre_ext += _recompile_suffix
     out_lib = go.declare_file(go, name = source.library.name, ext = pre_ext + ".a")
 
-    # store __.PKGDEF and nogo facts in .x
+    # store export information for compiling dependent packages separately
     out_export = go.declare_file(go, name = source.library.name, ext = pre_ext + ".x")
     out_cgo_export_h = None  # set if cgo used in c-shared or c-archive mode
+    out_facts = None
+    nogo = go.get_nogo(go)
+    if nogo:
+        out_facts = go.declare_file(go, name = source.library.name, ext = pre_ext + ".facts")
 
     direct = [get_archive(dep) for dep in source.deps]
     runfiles = source.runfiles
@@ -105,6 +109,8 @@ def emit_archive(go, source = None, _recompile_suffix = "", recompile_internal_d
             archives = direct,
             out_lib = out_lib,
             out_export = out_export,
+            out_facts = out_facts,
+            nogo = nogo,
             out_cgo_export_h = out_cgo_export_h,
             gc_goopts = source.gc_goopts,
             cgo = True,
@@ -129,6 +135,8 @@ def emit_archive(go, source = None, _recompile_suffix = "", recompile_internal_d
             archives = direct,
             out_lib = out_lib,
             out_export = out_export,
+            out_facts = out_facts,
+            nogo = nogo,
             gc_goopts = source.gc_goopts,
             cgo = False,
             testfilter = testfilter,
@@ -173,6 +181,7 @@ def emit_archive(go, source = None, _recompile_suffix = "", recompile_internal_d
         # Information needed by dependents
         file = out_lib,
         export_file = out_export,
+        facts_file = out_facts,
         data_files = as_tuple(data_files),
         _cgo_deps = as_tuple(cgo_deps),
     )

go/private/actions/compilepkg.bzl

@@ -28,6 +28,18 @@ def _archive(v):
         v.data.export_file.path if v.data.export_file else v.data.file.path,
     )
 
+def _facts(v):
+    facts_file = v.data.facts_file
+    if not facts_file:
+        return None
+    importpaths = [v.data.importpath]
+    importpaths.extend(v.data.importpath_aliases)
+    return "{}={}={}".format(
+        ":".join(importpaths),
+        v.data.importmap,
+        facts_file.path,
+    )
+
 def _embedroot_arg(src):
     return src.root.path
 
@@ -55,6 +67,8 @@ def emit_compilepkg(
         clinkopts = [],
         out_lib = None,
         out_export = None,
+        out_facts = None,
+        nogo = None,
         out_cgo_export_h = None,
         gc_goopts = [],
         testfilter = None,  # TODO: remove when test action compiles packages
@@ -64,6 +78,8 @@ def emit_compilepkg(
         fail("sources is a required parameter")
     if out_lib == None:
         fail("out_lib is a required parameter")
+    if bool(nogo) != bool(out_facts):
+        fail("nogo must be specified if and only if out_facts is specified")
 
     inputs = (sources + embedsrcs + [go.package_list] +
               [archive.data.export_file for archive in archives] +
@@ -108,10 +124,13 @@ def emit_compilepkg(
         args.add("-p", importmap)
     args.add("-package_list", go.package_list)
 
-    args.add("-o", out_lib)
-    args.add("-x", out_export)
-    nogo = go.get_nogo(go)
+    args.add("-lo", out_lib)
+    args.add("-o", out_export)
     if nogo:
+        args.add_all(archives, before_each = "-facts", map_each = _facts)
+        inputs.extend([archive.data.facts_file for archive in archives if archive.data.facts_file])
+        args.add("-out_facts", out_facts)
+        outputs.append(out_facts)
         args.add("-nogo", nogo)
         inputs.append(nogo)
     if out_cgo_export_h:

go/providers.rst

@@ -260,7 +260,15 @@ rule.  Instead, it's referenced in the ``data`` field of GoArchive_.
 +--------------------------------+-----------------------------------------------------------------+
 | :param:`file`                  | :type:`File`                                                    |
 +--------------------------------+-----------------------------------------------------------------+
-| The archive file produced when this library is compiled.                                         |
+| The archive file for the linker produced when this library is compiled.                          |
++--------------------------------+-----------------------------------------------------------------+
+| :param:`export_file`           | :type:`File`                                                    |
++--------------------------------+-----------------------------------------------------------------+
+| The archive file for compilation of dependent libraries produced when this library is compiled.  |
++--------------------------------+-----------------------------------------------------------------+
+| :param:`facts_file`            | :type:`File`                                                    |
++--------------------------------+-----------------------------------------------------------------+
+| The serialized facts for this library produced when nogo ran for this library.                   |
 +--------------------------------+-----------------------------------------------------------------+
 | :param:`srcs`                  | :type:`tuple of File`                                           |
 +--------------------------------+-----------------------------------------------------------------+

go/tools/builders/BUILD.bazel

@@ -76,7 +76,6 @@ filegroup(
         "generate_test_main.go",
         "importcfg.go",
         "link.go",
-        "pack.go",
         "read.go",
         "replicate.go",
         "stdlib.go",
@@ -97,7 +96,6 @@ go_source(
         "nogo_typeparams_go117.go",
         "nogo_typeparams_go118.go",
         "nolint.go",
-        "pack.go",
     ],
     # //go/tools/builders:nogo_srcs is considered a different target by
     # Bazel's visibility check than

go/tools/builders/ar.go

@@ -23,6 +23,18 @@ import (
 	"strings"
 )
 
+const (
+	// arHeader appears at the beginning of archives created by "ar" and
+	// "go tool pack" on all platforms.
+	arHeader = "!<arch>\n"
+
+	// entryLength is the size in bytes of the metadata preceding each file
+	// in an archive.
+	entryLength = 60
+)
+
+var zeroBytes = []byte("0                    ")
+
 type header struct {
 	NameRaw     [16]byte
 	ModTimeRaw  [12]byte

go/tools/builders/cgo2.go

@@ -23,9 +23,11 @@ package main
 import (
 	"bytes"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strings"
 )
 
@@ -395,3 +397,34 @@ func (e cgoError) Error() string {
 	fmt.Fprintf(b, "Ensure that 'cgo = True' is set and the C/C++ toolchain is configured.")
 	return b.String()
 }
+
+func copyFile(inPath, outPath string) error {
+	inFile, err := os.Open(inPath)
+	if err != nil {
+		return err
+	}
+	defer inFile.Close()
+	outFile, err := os.OpenFile(outPath, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0666)
+	if err != nil {
+		return err
+	}
+	defer outFile.Close()
+	_, err = io.Copy(outFile, inFile)
+	return err
+}
+
+func linkFile(inPath, outPath string) error {
+	inPath, err := filepath.Abs(inPath)
+	if err != nil {
+		return err
+	}
+	return os.Symlink(inPath, outPath)
+}
+
+func copyOrLinkFile(inPath, outPath string) error {
+	if runtime.GOOS == "windows" {
+		return copyFile(inPath, outPath)
+	} else {
+		return linkFile(inPath, outPath)
+	}
+}