Enable language specific baselines via feature flag

CHANGELOG.md

@@ -7,6 +7,7 @@ See the [releases page](https://github.com/github/codeql-action/releases) for th
 - Log a warning if the amount of available disk space runs low during a code scanning run. [#1825](https://github.com/github/codeql-action/pull/1825)
 - When downloading CodeQL bundle version 2.13.4 and later, cache these bundles in the Actions tool cache using a simpler version number. [#1832](https://github.com/github/codeql-action/pull/1832)
 - Fix an issue that first appeared in CodeQL Action v2.21.2 that prevented CodeQL invocations from being logged. [#1833](https://github.com/github/codeql-action/pull/1833)
+- We are rolling out a feature in August 2023 that will improve the quality of file coverage information. [#1835](https://github.com/github/codeql-action/pull/1835)
 
 ## 2.21.3 - 08 Aug 2023
 

src/codeql.ts

@@ -574,6 +574,13 @@ export async function getCodeQLForCmd(
       ) {
         extraArgs.push(`--qlconfig-file=${qlconfigFile}`);
       }
+
+      if (
+        await features.getValue(Feature.LanguageBaselineConfigEnabled, this)
+      ) {
+        extraArgs.push("--calculate-language-specific-baseline");
+      }
+
       await runTool(
         cmd,
         [

src/feature-flags.ts

@@ -28,6 +28,11 @@ export const CODEQL_VERSION_ANALYSIS_SUMMARY_V2 = "2.14.0";
  */
 export const CODEQL_VERSION_INTRA_LAYER_PARALLELISM = "2.14.0";
 
+/**
+ * Versions 2.14.2+ of the CodeQL CLI support language-specific baseline configuration.
+ */
+export const CODEQL_VERSION_LANGUAGE_BASELINE_CONFIG = "2.14.2";
+
 export interface CodeQLDefaultVersionInfo {
   cliVersion: string;
   tagName: string;
@@ -55,6 +60,7 @@ export enum Feature {
   DisablePythonDependencyInstallationEnabled = "disable_python_dependency_installation_enabled",
   EvaluatorIntraLayerParallelismEnabled = "evaluator_intra_layer_parallelism_enabled",
   ExportDiagnosticsEnabled = "export_diagnostics_enabled",
+  LanguageBaselineConfigEnabled = "language_baseline_config_enabled",
   MlPoweredQueriesEnabled = "ml_powered_queries_enabled",
   QaTelemetryEnabled = "qa_telemetry_enabled",
   ScalingReservedRamEnabled = "scaling_reserved_ram_enabled",
@@ -95,6 +101,11 @@ export const featureConfig: Record<
     minimumVersion: "2.12.4",
     defaultValue: true,
   },
+  [Feature.LanguageBaselineConfigEnabled]: {
+    envVar: "CODEQL_ACTION_LANGUAGE_BASELINE_CONFIG",
+    minimumVersion: CODEQL_VERSION_LANGUAGE_BASELINE_CONFIG,
+    defaultValue: false,
+  },
   [Feature.MlPoweredQueriesEnabled]: {
     envVar: "CODEQL_ML_POWERED_QUERIES",
     minimumVersion: undefined,