Swift: improve diagnostics for OS incompatibility

* do not mention any more that one might make analysis happen on Linux with
  advanced setup
* say that outright Swift analysis is only supported on macOS, not just
  autobuild.
* emit the error diagnostics even for traced builds, not only for autobuilds
  (by using a dummy `extractor` executable).

swift/BUILD.bazel

@@ -26,8 +26,14 @@ filegroup(
 )
 
 codeql_pkg_files(
-    name = "autobuilder-incompatible-os",
-    exes = ["//swift/tools/diagnostics:autobuilder-incompatible-os"],
+    name = "incompatible-os",
+    exes = ["//swift/tools/incompatible-os"],
+    renames = select_os(
+        otherwise = {},
+        windows = {
+            "//swift/tools/incompatible-os": "extractor.exe",
+        },
+    ),
 )
 
 codeql_pkg_runfiles(
@@ -42,7 +48,7 @@ pkg_filegroup(
             ":autobuilder-files",
         ],
         otherwise = [
-            ":autobuilder-incompatible-os",
+            ":incompatible-os",
         ],
     ),
     prefix = "tools/{CODEQL_PLATFORM}",
@@ -64,6 +70,13 @@ pkg_filegroup(
     prefix = "tools/{CODEQL_PLATFORM}",
 )
 
+pkg_filegroup(
+    name = "incompatible-linux-extractor",
+    srcs = ["//swift/extractor:incompatible"],
+    prefix = "tools/{CODEQL_PLATFORM}",
+    target_compatible_with = ["@platforms//os:linux"],
+)
+
 codeql_pkg_files(
     name = "root-files",
     srcs = [
@@ -86,7 +99,7 @@ zip_map = {
             ":tools",
             "//swift/downgrades",
         ] + select_os(
-            linux = [":extractor"] if linux_included else [],
+            linux = [":extractor"] if linux_included else [":incompatible-linux-extractor"],
             macos = [":extractor"],
             windows = [],
         ),

swift/extractor/BUILD.bazel

@@ -1,5 +1,5 @@
 load("@rules_shell//shell:sh_binary.bzl", "sh_binary")
-load("//misc/bazel:pkg.bzl", "codeql_pkg_runfiles")
+load("//misc/bazel:pkg.bzl", "codeql_pkg_files", "codeql_pkg_runfiles")
 load("//swift:rules.bzl", "swift_cc_binary")
 
 swift_cc_binary(
@@ -36,3 +36,11 @@ codeql_pkg_runfiles(
     exes = [":extractor"],
     visibility = ["//swift:__pkg__"],
 )
+
+codeql_pkg_files(
+    name = "incompatible",
+    exes = ["incompatible-extractor.sh"],
+    renames = {"incompatible-extractor.sh": "extractor"},
+    target_compatible_with = ["@platforms//os:linux"],
+    visibility = ["//swift:__pkg__"],
+)

swift/extractor/incompatible-extractor.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+
+exec -a "$0" "$(dirname $0)/incompatible-os"

swift/ql/integration-tests/autobuilder/unsupported-os/diagnostics.expected

@@ -1,9 +1,9 @@
 {
-  "markdownMessage": "Currently, `autobuild` for Swift analysis is only supported on macOS.\n\n[Change the Actions runner][1] to run on macOS.\n\nYou may be able to run analysis on Linux by setting up a [manual build command][2].\n\n[1]: https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idruns-on\n[2]: https://docs.github.com/en/enterprise-server/code-security/code-scanning/automatically-scanning-your-code-for-vulnerabilities-and-errors/configuring-the-codeql-workflow-for-compiled-languages#adding-build-steps-for-a-compiled-language",
+  "markdownMessage": "Currently, Swift analysis is only supported on macOS.\n\n[Change the Actions runner][1] to run on macOS.\n\n[1]: https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idruns-on",
   "severity": "error",
   "source": {
     "extractorName": "swift",
-    "id": "swift/autobuilder/incompatible-os",
+    "id": "swift/extractor/incompatible-os",
     "name": "Incompatible operating system (expected macOS)"
   },
   "visibility": {

swift/tools/autobuild.cmd

@@ -1 +1 @@
-"%CODEQL_EXTRACTOR_SWIFT_ROOT%/tools/%CODEQL_PLATFORM%/autobuilder-incompatible-os.exe"
+"%CODEQL_EXTRACTOR_SWIFT_ROOT%/tools/%CODEQL_PLATFORM%/exctractor.exe"

swift/tools/autobuild.sh

@@ -5,5 +5,5 @@ if [[ "$OSTYPE" == "darwin"* ]]; then
   export CODEQL_SWIFT_POD_EXEC=`which pod`
   exec "${CODEQL_EXTRACTOR_SWIFT_ROOT}/tools/${CODEQL_PLATFORM}/swift-autobuilder"
 else
-  exec "${CODEQL_EXTRACTOR_SWIFT_ROOT}/tools/${CODEQL_PLATFORM}/autobuilder-incompatible-os"
+  exec "${CODEQL_EXTRACTOR_SWIFT_ROOT}/tools/${CODEQL_PLATFORM}/incompatible-os"
 fi

swift/tools/diagnostics/BUILD.bazel → swift/tools/incompatible-os/BUILD.bazel

@@ -1,8 +1,8 @@
 load("//swift:rules.bzl", "swift_cc_binary")
 
 swift_cc_binary(
-    name = "autobuilder-incompatible-os",
-    srcs = ["AutobuilderIncompatibleOs.cpp"],
+    name = "incompatible-os",
+    srcs = ["IncompatibleOs.cpp"],
     # No restrictions (Windows allowed)
     target_compatible_with = [],
     visibility = ["//swift:__subpackages__"],

swift/tools/incompatible-os/IncompatibleOs.cpp

@@ -0,0 +1,28 @@
+// Unconditionally emits a diagnostic about running the autobuilder on an incompatible, non-macOS OS
+// and exits with an error code.
+//
+// This is implemented as a C++ binary instead of a hardcoded JSON file so we can leverage existing
+// diagnostic machinery for emitting correct timestamps, generating correct file names, etc.
+
+#include "swift/logging/SwiftLogging.h"
+
+const std::string_view codeql::programName = "extractor";
+const std::string_view codeql::extractorName = "swift";
+
+constexpr codeql::Diagnostic incompatibleOs{
+    .id = "incompatible-os",
+    .name = "Incompatible operating system (expected macOS)",
+    .action = "[Change the Actions runner][1] to run on macOS.\n\n"
+              "[1]: "
+              "https://docs.github.com/en/actions/using-workflows/"
+              "workflow-syntax-for-github-actions#jobsjob_idruns-on"};
+
+static codeql::Logger& logger() {
+  static codeql::Logger ret{"main"};
+  return ret;
+}
+
+int main() {
+  DIAGNOSE_ERROR(incompatibleOs, "Currently, Swift analysis is only supported on macOS.");
+  return 1;
+}