Refactor `GeneratesMethodGenerator` into a tiny orchestrator with focused helper components by Copilot · Pull Request #14 · dex3r/EasySourceGenerators

Copilot · 2026-02-27T19:00:39Z

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Apply null-safe PortableExecutableReference.FilePath handling in runtime resolver/lookups
Run targeted tests for generator changes
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Original prompt

This section details on the original issue you should resolve

<issue_title>Refactor GeneratesMethodGenerator</issue_title>
<issue_description>Refactor GeneratesMethodGenerator:

split it nicely into small, testable classes

move diagnostic descriptions to a separate file (if that is ok, maybe they NEED to be there??)

replace var with actuall types

do other common refactoring task as you see fit

make code as self-documenting as possible, with good naming, avoid comments

make sure all tests still pass</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes Refactor GeneratesMethodGenerator #13

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Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>

dex3r

That is a good start. Now, extract even more code out of GeneratesMethodGenerator, so it's very tiny. The helper classes and methods should be small and unit-testable.

Copilot

Pull request overview

Refactors GeneratesMethodGenerator to improve structure by separating target collection/validation and centralizing diagnostic descriptors, while keeping the generation logic and outputs the same.

Changes:

Extracted [GeneratesMethod] discovery/validation into GeneratesMethodGenerationTargetCollector and introduced GeneratesMethodGenerationTarget as a typed transfer model.
Centralized diagnostic descriptors into GeneratesMethodGenerator.Diagnostics.cs and updated generator code to reference them.
Replaced var with explicit types in touched generator paths.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
MattSourceGenHelpers.Generators/GeneratesMethodGenerator.cs	Updated generator to consume collected targets, reference centralized diagnostics, and use explicit typing.
MattSourceGenHelpers.Generators/GeneratesMethodGenerator.Diagnostics.cs	New centralized diagnostic descriptor definitions (MSGH001–MSGH004).
MattSourceGenHelpers.Generators/GeneratesMethodGenerationTargetCollector.cs	New collector that discovers/validates generator methods and emits validation diagnostics.

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Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>

Copilot · 2026-02-27T19:47:55Z

That is a good start. Now, extract even more code out of GeneratesMethodGenerator, so it's very tiny. The helper classes and methods should be small and unit-testable.

Done in 681caa0 (with follow-up polish in e89e0c4). GeneratesMethodGenerator is now kept very small, with orchestration moved to GeneratesMethodGenerationPipeline and the remaining logic split into focused helper classes: GeneratesMethodPatternSourceBuilder and GeneratesMethodExecutionRuntime.

Copilot

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

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Copilot · 2026-02-28T08:52:15Z

+                PortableExecutableReference? match = compilation.References
+                    .OfType<PortableExecutableReference>()
+                    .FirstOrDefault(reference => string.Equals(
+                        Path.GetFileNameWithoutExtension(reference.FilePath),
+                        assemblyName.Name,
+                        StringComparison.OrdinalIgnoreCase));
+                return match?.FilePath != null ? context.LoadFromAssemblyPath(match.FilePath) : null;


PortableExecutableReference.FilePath is nullable, but the predicate calls Path.GetFileNameWithoutExtension(reference.FilePath) without a null check. This can throw (and also triggers nullable warnings) when the compilation contains in-memory references with FilePath == null. Consider filtering to reference.FilePath is not null before calling Path.* (and/or using a safe fallback).

Fixed in 095d0c1 by guarding reference.FilePath is not null before calling Path.GetFileNameWithoutExtension in the resolver lookup.

Copilot · 2026-02-28T08:52:15Z

+            PortableExecutableReference? abstractionsReference = compilation.References
+                .OfType<PortableExecutableReference>()
+                .FirstOrDefault(reference => string.Equals(
+                    Path.GetFileNameWithoutExtension(reference.FilePath),
+                    "MattSourceGenHelpers.Abstractions",
+                    StringComparison.OrdinalIgnoreCase));


The lookup for the Abstractions reference assumes reference.FilePath is non-null (Path.GetFileNameWithoutExtension(reference.FilePath)). FilePath can be null for some metadata references, which would crash the generator. Add a null check in the predicate (or otherwise handle null paths) before calling Path.*.

Fixed in 095d0c1 by adding a null-safe predicate for reference.FilePath in the Abstractions-reference lookup.

Copilot · 2026-02-28T08:52:15Z

+                    .FirstOrDefault(reference => string.Equals(
+                        Path.GetFileNameWithoutExtension(reference.FilePath),
+                        assemblyName.Name,
+                        StringComparison.OrdinalIgnoreCase));


Same nullable FilePath issue in the AssemblyLoadContext resolver: Path.GetFileNameWithoutExtension(reference.FilePath) can throw if FilePath is null. Guard with reference.FilePath is not null before using it.

Suggested change

.FirstOrDefault(reference => string.Equals(

Path.GetFileNameWithoutExtension(reference.FilePath),

assemblyName.Name,

StringComparison.OrdinalIgnoreCase));

.FirstOrDefault(reference =>

reference.FilePath is not null &&

string.Equals(

Path.GetFileNameWithoutExtension(reference.FilePath),

assemblyName.Name,

StringComparison.OrdinalIgnoreCase));

Addressed in 095d0c1 with the suggested null guard in the second AssemblyLoadContext resolver lookup.

dex3r · 2026-02-28T11:23:22Z

@copilot apply changes based on the comments in this thread

Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>

Copilot · 2026-02-28T11:26:20Z

@copilot apply changes based on the comments in this thread

Applied in 095d0c1. I implemented the thread feedback by adding null guards for PortableExecutableReference.FilePath in all three metadata-reference lookups in GeneratesMethodExecutionRuntime to avoid null-path crashes with in-memory references.

Initial plan

ae88967

Copilot AI assigned Copilot and dex3r Feb 27, 2026

Copilot started work on behalf of dex3r February 27, 2026 19:00 View session

Copilot AI and others added 2 commits February 27, 2026 19:05

refactor: extract GeneratesMethod diagnostics and method collection

90d0eff

Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>

chore: address review feedback and finalize generator refactor

2eb1a2b

Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Refactor GeneratesMethodGenerator for better structure and readability~~ Refactor GeneratesMethodGenerator into focused components and centralize diagnostics Feb 27, 2026

Copilot finished work on behalf of dex3r February 27, 2026 19:08

dex3r marked this pull request as ready for review February 27, 2026 19:39

Copilot AI review requested due to automatic review settings February 27, 2026 19:39

Copilot started reviewing on behalf of dex3r February 27, 2026 19:39 View session

dex3r requested changes Feb 27, 2026

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Copilot started work on behalf of dex3r February 27, 2026 19:41 View session

Copilot AI reviewed Feb 27, 2026

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Comment thread MattSourceGenHelpers.Generators/GeneratesMethodGenerator.cs Outdated

Comment thread MattSourceGenHelpers.Generators/GeneratesMethodGenerator.cs Outdated

Copilot AI and others added 2 commits February 27, 2026 19:44

refactor: shrink GeneratesMethodGenerator and extract runtime helpers

681caa0

Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>

refactor: split generator orchestration and pattern/runtime helpers

e89e0c4

Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>

Copilot AI changed the title ~~Refactor GeneratesMethodGenerator into focused components and centralize diagnostics~~ Refactor GeneratesMethodGenerator into a tiny orchestrator with focused helper components Feb 27, 2026

Copilot finished work on behalf of dex3r February 27, 2026 19:48

dex3r requested a review from Copilot February 28, 2026 08:47

Copilot started reviewing on behalf of dex3r February 28, 2026 08:48 View session

dex3r approved these changes Feb 28, 2026

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Copilot AI reviewed Feb 28, 2026

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Copilot started work on behalf of dex3r February 28, 2026 11:23 View session

fix: guard null FilePath in metadata reference lookups

095d0c1

Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>

Copilot finished work on behalf of dex3r February 28, 2026 11:27

dex3r merged commit 1aa7794 into main Feb 28, 2026
1 check passed

dex3r deleted the copilot/refactor-generates-method-generator branch February 28, 2026 12:20

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Copilot AI commented Feb 27, 2026 •

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