remove gotmp dir

Author: dzbarsky

go/private/rules/binary.bzl

@@ -486,8 +486,10 @@ def _go_tool_binary_impl(ctx):
 
     out = ctx.actions.declare_file(name)
 
-    # Using pre-declared directory for temporary output to avoid needing to use shell to create it.
-    gotmp = ctx.actions.declare_directory(name + "_gotmp")
+    # Using pre-declared directory for temporary output to avoid dependencies
+    # on shell or non-hermetic coreutils.
+    gotmp = ctx.actions.declare_directory("gotmp")
+
     if sdk.goos == "windows":
         cmd = """@echo off
 set GOMAXPROCS=1
@@ -525,22 +527,14 @@ exit /b %GO_EXIT_CODE%
             mnemonic = "GoToolchainBinaryBuild",
         )
     else:
-        # A dummy action to generate `gotmp`; this way the compilation below can avoid listing it in `outputs`.
-        # The net effect is to avoid copying out the GOCACHE when actions run sandboxed.
-        # Incidentally, this makes the reproducibility test pass.
-        ctx.actions.write(
-            output = gotmp,
-            content = "",
-        )
-
-        # In case actions are running unsandboxed, GOCACHE in `gotmp` may have been polluted.
-        # -a flag forces a rebuild so we are not affected by it.
+        # -a flag instructs the compiler to not read from GOCACHE and force a rebuild.
+        # This provides extra safety in cases of unsandboxed execution.
         args = ctx.actions.args()
         args.add("build")
         args.add("-a")
         args.add("-o", out)
         args.add("-trimpath")
-        args.add("-ldflags", ctx.attr.ldflags, format = '-buildid="" %s')
+        args.add("-ldflags", ctx.attr.ldflags, format = '-w -s -buildid="" %s')
         args.add_all(ctx.files.srcs)
 
         ctx.actions.run(
@@ -552,17 +546,14 @@ exit /b %GO_EXIT_CODE%
                 "GO111MODULE": "off",
                 "GOTELEMETRY": "off",
                 "GOENV": "off",
-                # GOCACHE and GOPATH will default themselves to locations under $HOME.
-                # Otherwise we would need to set them explicitly, in which case they must be absolute paths.
-                # That would require a wrapper script/shell dependency.
                 "HOME": gotmp.path,
             },
             inputs = depset(
                 ctx.files.srcs,
                 transitive = [sdk.headers, sdk.srcs, sdk.libs, sdk.tools],
             ),
-            outputs = [out],
             toolchain = None,
+            outputs = [out, gotmp],
             mnemonic = "GoToolchainBinaryBuild",
         )
 

tests/integration/reproducibility/reproducibility_test.go

@@ -221,6 +221,11 @@ func Test(t *testing.T) {
 			go func(i int) {
 				defer wg.Done()
 				dirHashes[i], errs[i] = hashFiles(filepath.Join(dirs[i], "bazel-out/"), func(root, path string) bool {
+					// Exclude the GOCACHE that was written for go_tool_binary.
+					if strings.HasSuffix(path, "/gotmp") {
+						return true
+					}
+
 					// Hash everything but actions stdout/stderr and the volatile-status.txt file
 					// as they are expected to change
 					return strings.HasPrefix(path, filepath.Join(root, "_tmp")) ||