VersionInfo: allow non-linkstamp rules to link in definitions

bazel/BUILD

@@ -227,6 +227,11 @@ config_setting(
     values = {"cpu": "ios_arm64e"},
 )
 
+config_setting(
+    name = "manual_stamp",
+    values = {"define": "manual_stamp=manual_stamp"},
+)
+
 alias(
     name = "apple",
     actual = select(

source/common/common/BUILD

@@ -251,6 +251,23 @@ genrule(
     cmd = """echo "#define BUILD_VERSION_NUMBER \\"$$(cat $<)\\"" >$@""",
 )
 
+genrule(
+    name = "generate_version_linkstamp",
+    outs = ["lib/version_linkstamp.h"],
+    cmd = "$(location //source/common/common:generate_version_linkstamp.sh) >> $@",
+    # Undocumented attr to depend on workspace status files.
+    # https://github.com/bazelbuild/bazel/issues/4942
+    # Used here because generate_version_linkstamp.sh depends on the workspace status files.
+    stamp = 1,
+    tools = ["//source/common/common:generate_version_linkstamp.sh"],
+)
+
+genrule(
+    name = "generate_version_linkstamp_empty",
+    outs = ["empty/version_linkstamp.h"],
+    cmd = """>$@""",
+)
+
 envoy_cc_library(
     name = "version_includes",
     hdrs = [
@@ -262,11 +279,21 @@ envoy_cc_library(
 envoy_cc_library(
     name = "version_lib",
     srcs = ["version.cc"],
+    hdrs = select({
+        "//bazel:manual_stamp": [":generate_version_linkstamp"],
+        # By default the header file is empty.
+        # This is done so that the definitions linked via the linkstamp rule don't cause collisions.
+        "//conditions:default": [":generate_version_linkstamp_empty"],
+    }),
     copts = envoy_select_boringssl(
         ["-DENVOY_SSL_VERSION=\\\"BoringSSL-FIPS\\\""],
         ["-DENVOY_SSL_VERSION=\\\"BoringSSL\\\""],
     ),
     linkstamp = "version_linkstamp.cc",
+    strip_include_prefix = select({
+        "//bazel:manual_stamp": "lib",
+        "//conditions:default": "empty",
+    }),
     deps = [
         ":version_includes",
         "//source/common/common:macros",

source/common/common/generate_version_linkstamp.sh

@@ -0,0 +1,13 @@
+#!/bin/bash
+
+# This script generates a header file that is used by version_lib whenever linkstamp is not allowed.
+# linkstamp is used to link in version_linkstamp.cc into the version_lib.
+# However, linkstamp is not available to non-binary bazel targets.
+# This means that if the topmost target being used to compile version_lib is a envoy_cc_library or related, linkstamp will not be in effect.
+# In turn this means that version_linkstamp.cc is not linked, and the build_scm_revision and build_scm_status are unknown symbols to the linker.
+build_scm_revision=$(grep BUILD_SCM_REVISION bazel-out/volatile-status.txt | sed 's/^BUILD_SCM_REVISION //' | tr -d '\\n')
+
+echo "extern const char build_scm_revision[];"
+echo "extern const char build_scm_status[];"
+echo "const char build_scm_revision[] = \"$build_scm_revision\";"
+echo "const char build_scm_status[] = \"Library\";"

source/common/common/version.cc

@@ -4,6 +4,7 @@
 
 #include "common/common/fmt.h"
 #include "common/common/macros.h"
+#include "common/common/version_linkstamp.h"
 
 extern const char build_scm_revision[];
 extern const char build_scm_status[];