go_binary: Add support to set a default GODEBUG per binary

docs/go/core/rules.md

@@ -127,7 +127,7 @@ Rules
 <pre>
 go_binary(<a href="#go_binary-name">name</a>, <a href="#go_binary-basename">basename</a>, <a href="#go_binary-cdeps">cdeps</a>, <a href="#go_binary-cgo">cgo</a>, <a href="#go_binary-clinkopts">clinkopts</a>, <a href="#go_binary-copts">copts</a>, <a href="#go_binary-cppopts">cppopts</a>, <a href="#go_binary-cxxopts">cxxopts</a>, <a href="#go_binary-data">data</a>, <a href="#go_binary-deps">deps</a>, <a href="#go_binary-embed">embed</a>,
           <a href="#go_binary-embedsrcs">embedsrcs</a>, <a href="#go_binary-env">env</a>, <a href="#go_binary-gc_goopts">gc_goopts</a>, <a href="#go_binary-gc_linkopts">gc_linkopts</a>, <a href="#go_binary-goarch">goarch</a>, <a href="#go_binary-goos">goos</a>, <a href="#go_binary-gotags">gotags</a>, <a href="#go_binary-importpath">importpath</a>, <a href="#go_binary-linkmode">linkmode</a>, <a href="#go_binary-msan">msan</a>,
-          <a href="#go_binary-out">out</a>, <a href="#go_binary-pgoprofile">pgoprofile</a>, <a href="#go_binary-pure">pure</a>, <a href="#go_binary-race">race</a>, <a href="#go_binary-srcs">srcs</a>, <a href="#go_binary-static">static</a>, <a href="#go_binary-x_defs">x_defs</a>)
+          <a href="#go_binary-out">out</a>, <a href="#go_binary-pgoprofile">pgoprofile</a>, <a href="#go_binary-pure">pure</a>, <a href="#go_binary-race">race</a>, <a href="#go_binary-srcs">srcs</a>, <a href="#go_binary-static">static</a>, <a href="#go_binary-x_defs">x_defs</a>, <a href="#go_binary-godebug_default">godebug_default</a>)
 </pre>
 
 This builds an executable from a set of source files,
@@ -175,6 +175,7 @@ This builds an executable from a set of source files,
 | <a id="go_binary-srcs"></a>srcs |  The list of Go source files that are compiled to create the package.                 Only <code>.go</code>, <code>.s</code>, and <code>.syso</code> files are permitted, unless the <code>cgo</code>                 attribute is set, in which case,                 <code>.c .cc .cpp .cxx .h .hh .hpp .hxx .inc .m .mm</code>                 files are also permitted. Files may be filtered at build time                 using Go [build constraints].   | <a href="https://bazel.build/concepts/labels">List of labels</a> | optional | [] |
 | <a id="go_binary-static"></a>static |  Controls whether a binary is statically linked. May be one of <code>on</code>,                 <code>off</code>, or <code>auto</code>. Not available on all platforms or in all                 modes. It's usually better to control this on the command line with                 <code>--@io_bazel_rules_go//go/config:static</code>. See [mode attributes],                 specifically [static].   | String | optional | "auto" |
 | <a id="go_binary-x_defs"></a>x_defs |  Map of defines to add to the go link command.                 See [Defines and stamping] for examples of how to use these.   | <a href="https://bazel.build/rules/lib/dict">Dictionary: String -> String</a> | optional | {} |
+| <a id="go_binary-godebug_default"></a>godebug_default | Map of default GODEBUG keys and values |  <a href="https://bazel.build/rules/lib/dict">Dictionary: String -> String</a> | optional | {} |
 
 
 

go/private/actions/archive.bzl

@@ -208,4 +208,5 @@ def emit_archive(go, source = None, _recompile_suffix = "", recompile_internal_d
         cgo_deps = depset(transitive = [cgo_deps] + [a.cgo_deps for a in direct]),
         cgo_exports = cgo_exports,
         runfiles = runfiles,
+        godebug_default = getattr(source, "godebug_default", None),
     )

go/private/actions/link.bzl

@@ -140,6 +140,11 @@ def emit_link(
     ]))
     extldflags.extend(cgo_rpaths)
 
+    godebug_default = archive.godebug_default
+    if godebug_default:
+        builder_args.add("-X", "runtime.godebugDefault={}".format(
+            ",".join(["{}={}".format(k, v) for k, v in godebug_default.items()])))
+
     # Process x_defs, and record whether stamping is used.
     stamp_x_defs_volatile = False
     stamp_x_defs_stable = False

go/private/context.bzl

@@ -290,6 +290,7 @@ def _library_to_source(go, attr, library, coverage_instrumented, verify_resolver
         _merge_embed(source, e)
 
     source["deps"] = _dedup_archives(source["deps"])
+    source["godebug_default"] = getattr(attr, "godebug_default", None)
 
     x_defs = source["x_defs"]
     for k, v in getattr(attr, "x_defs", {}).items():

go/private/rules/binary.bzl

@@ -439,6 +439,9 @@ def _go_binary_kwargs(go_cc_aspects = []):
                 """,
                 default = "//go/config:empty",
             ),
+            "godebug_default": attr.string_dict(
+                doc = """Map of default GODEBUG values to add to the go link command.""",
+            ),
             "_go_context_data": attr.label(default = "//:go_context_data", cfg = go_transition),
             "_allowlist_function_transition": attr.label(
                 default = "@bazel_tools//tools/allowlists/function_transition_allowlist",

tests/core/go_binary/BUILD.bazel

@@ -241,7 +241,31 @@ go_binary(
 go_binary(
     name = "meaning2",
     srcs = [
-        "//tests/core/go_library:use_syso_srcs",
         "meaning2.go",
+        "//tests/core/go_library:use_syso_srcs",
     ],
 )
+
+go_binary(
+    name = "godebug_bin_godebug",
+    srcs = ["godebug_bin.go"],
+    godebug_default = {
+        "http2debug": "1",
+    },
+)
+
+go_binary(
+    name = "godebug_bin",
+    srcs = ["godebug_bin.go"],
+)
+
+go_test(
+    name = "godebug_test",
+    srcs = ["godebug_test.go"],
+    data = [
+        ":godebug_bin",
+        ":godebug_bin_godebug",
+    ],
+    rundir = ".",
+    deps = ["//go/tools/bazel:go_default_library"],
+)

tests/core/go_binary/README.rst

@@ -68,3 +68,7 @@ prefix
 ------
 This binary has a name that conflicts with a subdirectory. Its output file
 name should not have this conflict. Verifies `#2463`_.
+
+godebug_test
+------------
+Test that the ``godebug_default`` sets the default ``GODEBUG`` variables.

tests/core/go_binary/godebug_bin.go

@@ -0,0 +1,11 @@
+package main
+
+import (
+	"fmt"
+	"internal/godebug"
+)
+
+func main() {
+	http2debug := godebug.New("http2debug")
+	fmt.Printf("%v\n", http2debug)
+}

tests/core/go_binary/godebug_test.go

@@ -0,0 +1,44 @@
+package godebug
+
+import (
+	"os/exec"
+	"strings"
+	"testing"
+
+	"github.com/bazelbuild/rules_go/go/tools/bazel"
+)
+
+func TestGodebugDefaults(t *testing.T) {
+	tests := map[string]struct {
+		binary string
+		want   string
+	}{
+		"debug": {
+			binary: "godebug_bin_godebug",
+			want:   "http2debug=1",
+		},
+		"no_debug": {
+			binary: "godebug_bin",
+			want:   "http2debug=",
+		},
+	}
+
+	for testName, tc := range tests {
+		t.Run(testName, func(t *testing.T) {
+			bin, ok := bazel.FindBinary("tests/core/go_binary", tc.binary)
+			if !ok {
+				t.Fatalf("could not find %v binary", tc.binary)
+			}
+
+			out, err := exec.Command(bin).Output()
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			got := strings.TrimSpace(string(out))
+			if got != tc.want {
+				t.Errorf("got:%v\nwant:%s\n", got, tc.want)
+			}
+		})
+	}
+}