Prompt file imported from IvanMarkitan/dotnet-docs (.github/prompts/ErrorConsolidation.2.MergeExisting.prompt.md). Copyright stays with the author.

Merge existing error articles into a consolidated article

You are merging existing standalone compiler error/warning articles into a consolidated destination file. The user will provide:

• Destination filename — the consolidated .md file in docs/csharp/language-reference/compiler-messages/
• Theme description — the theme these errors relate to
• Source files — a list of existing error article files to merge (already approved by the user)

Key file locations

• Destination file: docs/csharp/language-reference/compiler-messages/{destination-filename}
• TOC file: docs/csharp/language-reference/toc.yml
• Redirection file: .openpublishing.redirection.csharp.json
• Redirect script: .github/skills/redirect-article/scripts/create-redirect-entry.ps1

Batch process: for each source file

Process the entire approved list. For each source file:

1. Read and extract

Read the source file and extract:

• The error code (from the filename or front matter, e.g., CS0220)
• The error message: extract the numeric portion of the error code, find the constant with that number in ../roslyn/src/Compilers/CSharp/Portable/Errors/ErrorCodes.cs, then find the matching <data> element in ../roslyn/src/Compilers/CSharp/Portable/CSharpResources.resx and read the verbatim text from its <value> child element.
• The article body content (everything after the front matter and H1)

2. Update the destination file

Front matter:

• Add the error code to f1_keywords in sorted numeric order.
• Add the error code to helpviewer_keywords in sorted numeric order.

Error list:

• Add an entry to the error list at the top of the article, in sorted numeric order. Format:

  - [**CS{NNNN}**](#anchor-tbd): *{verbatim compiler error message}*
  

  Use #anchor-tbd as a placeholder anchor — these will be finalized in the Consolidate phase. Handling format placeholders: The Roslyn source message may contain interpolation markers like '{0}', '{1}', etc. Replace these with descriptive terms that keep the text as close to the verbatim message as possible for SEO, while still reading as a coherent sentence. Use generic terms like 'type', 'value', 'operator', 'member', or 'method' based on the context of the error. For example, Constant value '{0}' cannot be converted to a '{1}' becomes Constant value 'value' cannot be converted to a 'type'. Look at the XML <comment> element following the <value> (if present) for hints about what each placeholder represents.

Content:

• Add the source file's content as a new H2 section at the end of the destination file:

  ## CS{NNNN}
  
  {source article content, adapted to fit as a section rather than standalone article}

  Remove any front matter, H1 heading, and See also sections from the pasted content. Adjust heading levels (H2 in the source becomes H3, etc.).

3. Create a redirect

Use the create-redirect-entry.ps1 script to add a redirect from the source file to the destination:

./.github/skills/redirect-article/scripts/create-redirect-entry.ps1 `
    -RedirectionFile ".openpublishing.redirection.csharp.json" `
    -SourcePath "docs/csharp/language-reference/compiler-messages/{source-filename}" `
    -RedirectUrl "/dotnet/csharp/language-reference/compiler-messages/{destination-filename-without-extension}"

If the source file is in docs/csharp/misc/, adjust the SourcePath accordingly.

4. Update the TOC

In docs/csharp/language-reference/toc.yml:

• Add the error code to the displayName for the destination file entry, maintaining numeric sort order.
• Find and remove the TOC entry for the source file (the - name: / href: block that references it).

5. Delete the source file

Delete the source markdown file from the repository.

After processing all files

Present a summary:

• List of all source files merged
• Count of error codes added to the destination
• List of redirects created
• List of TOC entries removed

Do not proceed to searching or consolidation — those are separate prompt files.