Merge pull request github#2430 from github/henrymercer/windows-diagnostics-fix

Fix writing diagnostics on Windows

Author: henrymercer

CHANGELOG.md

@@ -6,7 +6,7 @@ Note that the only difference between `v2` and `v3` of the CodeQL Action is the
 
 ## [UNRELEASED]
 
-No user facing changes.
+- Fix an issue where the CodeQL Action could not write diagnostic messages on Windows. This issue did not impact analysis quality. [#2430](https://github.com/github/codeql-action/pull/2430)
 
 ## 3.26.2 - 14 Aug 2024
 

lib/diagnostics.js

@@ -145,7 +145,8 @@ function writeDiagnostic(
 
     const jsonPath = path.resolve(
       diagnosticsPath,
-      `codeql-action-${diagnostic.timestamp}.json`,
+      // Remove colons from the timestamp as these are not allowed in Windows filenames.
+      `codeql-action-${diagnostic.timestamp.replaceAll(":", "")}.json`,
     );
 
     writeFileSync(jsonPath, JSON.stringify(diagnostic));