Switch to custom reflection (MrDocs.Describe) by gennaroprota · Pull Request #1171 · cppalliance/mrdocs

gennaroprota · 2026-03-23T10:33:46Z

This introduces our own (public) reflection facilities (replacing Boost.Describe/Boost.Mp11) and leverages them to eliminate per-type boilerplate.

github-actions · 2026-03-23T10:34:09Z

🚧 Danger.js checks for MrDocs are experimental; expect some rough edges while we tune the rules.

ℹ️ Info

Note

Commit 937aab7 (feat: make the reflection consumers public) touches 2578 source lines (non-test). Large change; add reviewer context if needed.

🧾 Changes by Scope

Scope	Lines Δ%	Lines Δ	Lines +	Lines -	Files Δ	Files +	Files ~	Files ↔	Files -
🛠️ Source	96%	4285	2082	2203	117	2	108	-	7
🤝 Third-party	4%	168	-	168	6	-	-	-	6
📄 Docs	<1%	14	7	7	1	-	1	-	-
🏗️ Build	<1%	5	-	5	1	-	1	-	-
📦 Other	<1%	4	-	4	1	-	1	-	-
🧪 Unit Tests	<1%	1	1	-	1	-	1	-	-
Total	100%	4477	2090	2387	127	2	112	-	13

Legend: Files + (added), Files ~ (modified), Files ↔ (renamed), Files - (removed)

🔝 Top Files

include/mrdocs/Support/Reflection.hpp (Source): 672 lines Δ (+672 / -0)
src/lib/Support/Reflection/Reflection.hpp (Source): 656 lines Δ (+0 / -656)
src/lib/Support/Reflection/Reflection.cpp (Source): 523 lines Δ (+0 / -523)

Generated by 🚫 dangerJS against 937aab7

codecov · 2026-03-23T10:35:04Z

Codecov Report

❌ Patch coverage is 89.05473% with 22 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.32%. Comparing base (9a12737) to head (937aab7).

Files with missing lines	Patch %	Lines
include/mrdocs/Support/Reflection.hpp	89.51%	8 Missing and 7 partials ⚠️
src/lib/Metadata/Info.cpp	66.66%	1 Missing and 2 partials ⚠️
src/lib/Metadata/Type.cpp	33.33%	0 Missing and 2 partials ⚠️
src/lib/Metadata/DocComment.cpp	91.66%	0 Missing and 1 partial ⚠️
src/lib/Metadata/DocComment/Inline.cpp	0.00%	1 Missing ⚠️

❌ Your patch check has failed because the patch coverage (89.05%) is below the target coverage (90.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1171      +/-   ##
===========================================
+ Coverage    78.26%   78.32%   +0.06%     
===========================================
  Files          348      345       -3     
  Lines        32540    32511      -29     
  Branches      6525     6512      -13     
===========================================
- Hits         25468    25465       -3     
+ Misses        4676     4656      -20     
+ Partials      2396     2390       -6

Flag	Coverage Δ
bootstrap	`81.89% <ø> (ø)`
cpp	`77.96% <89.05%> (+0.06%)`	⬆️

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cppalliance-bot · 2026-03-23T10:44:39Z

An automated preview of the documentation is available at https://1171.mrdocs.prtest2.cppalliance.org/index.html

If more commits are pushed to the pull request, the docs will rebuild at the same URL.

2026-03-27 17:09:25 UTC

Introduces include/mrdocs/Support/Describe.hpp — a minimal, C++23-only replacement for Boost.Describe and Boost.Mp11. Provides MRDOCS_DESCRIBE_STRUCT and MRDOCS_DESCRIBE_ENUM macros with compile-time member/base/enum descriptors and a fold-expression-based for_each. Adds MRDOCS_DESCRIBE_* calls next to every type definition. This moves reflection metadata from the private Reflection.hpp registry into the public headers, enabling future single-template operations (e.g. merge) that eliminate per-type boilerplate. Both descriptor systems coexist in this commit — no consumers are changed yet.

alandefreitas

LGTM (mostly)

docs/mrdocs.yml

alandefreitas · 2026-03-27T15:38:09Z

include/mrdocs/Support/EnumToString.hpp

-    requires boost::describe::has_describe_enumerators<Enum>::value
+    requires describe::has_describe_enumerators<Enum>::value
 std::string
 toString(Enum e)


Shouldn't this be with other reflection functions? What makes this one special?

alandefreitas · 2026-03-27T15:38:32Z

include/mrdocs/Support/Merge.hpp

 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
-// Copyright (c) 2026 Gennaro Prota (gennaro.prota@gmail.com)
+// Copyright (c) 2025 Gennaro Prota (gennaro.prota@gmail.com)


time machine? 😆

alandefreitas · 2026-03-27T15:39:38Z

src/lib/Metadata/Symbol/Enum.cpp

 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
-// Copyright (c) 2025 Alan de Freitas (alandefreitas@gmail.com)
+// Copyright (c) 2025 Gennaro Prota (gennaro.prota@gmail.com)


Heeeeeey! They would blame you now hehe

alandefreitas · 2026-03-27T15:40:31Z

src/lib/Metadata/Symbol/EnumConstant.cpp

 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
-// Copyright (c) 2025 Alan de Freitas (alandefreitas@gmail.com)
+// Copyright (c) 2025 Gennaro Prota (gennaro.prota@gmail.com)


Please review all of these...

alandefreitas · 2026-03-27T15:42:20Z

src/lib/Metadata/Symbol/Friend.cpp

-#include <mrdocs/Platform.hpp>
 #include <mrdocs/Metadata/Symbol/Friend.hpp>
+#include <mrdocs/Support/DomMapping.hpp>
+#include <mrdocs/Support/Merge.hpp>


I'm put "boost.describe" in <mrdocs/Support/Describe.hpp> and everything that uses the descriptions in <mrdocs/Support/Reflection.hpp> instead of one header per extra function (and some extra functions are actually going into Describe.hpp right now, which is confusing). But if you like it this way, that's also fine.

alandefreitas · 2026-03-27T15:43:02Z

src/lib/Metadata/Symbol/Friend.cpp


+template <typename IO>
+void
+tag_invoke(


Can't all of these tag_invokes be defined with reflection yet?

I tried that, but I was blocked by type erasure in LazyObject. Its virtual functions (get, visit, size, exists) are defined in LazyObject.hpp and call tag_invoke through lambdas. When the compiler instantiates LazyObjectImpl<ConceptSymbol, ... in DomCorpus.cpp, the generic tag_invoke template (from DomMapping.hpp) needs to be visible; but including it from LazyObject.hpp creates a circular dependency, and two-phase lookup doesn't find it, because LazyObjectIO lives in mrdocs::dom::detail, not in the type's namespace.

Removing the type erasure (making LazyObjectImpl see the tag_invoke directly) is the next step.

alandefreitas · 2026-03-27T15:43:31Z

src/lib/Metadata/Symbol/NamespaceAlias.cpp

 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
-// Copyright (c) 2025 Alan de Freitas (alandefreitas@gmail.com)
+// Copyright (c) 2025 Gennaro Prota (gennaro.prota@gmail.com)


Switches toString(Enum), mapReflectedType, mergeReflectedType, and XMLWriter from Boost.Describe/Boost.Mp11 to the custom MrDocs.Describe facility introduced in the previous commit. Removes #include <lib/Support/Reflection/Reflection.hpp> from all .cpp files that depended on it for BOOST_DESCRIBE macros (now superseded by per-header MRDOCS_DESCRIBE_* calls). Updates Reflection.cpp with direct includes and moves the Optional<DocComment> tag_invoke there. Deletes the now-unreferenced Reflection.hpp registry.

…emplate Adds a constrained merge(T&, T&&) template in MergeReflectedType.hpp that works for any type with MRDOCS_DESCRIBE_STRUCT. Non-template overloads (DocComment, SourceInfo, TemplateInfo, ExtractionMode, etc.) are still preferred by overload resolution. This eliminates a bunch of merge() functions that did nothing but forward to mergeReflected(), along with their MRDOCS_DECL declarations in public headers. Three .cpp files that existed solely for those one-liners are deleted entirely (Enum.cpp, EnumConstant.cpp, NamespaceAlias.cpp). Cleans up unused #include <mrdocs/Platform.hpp> from several .cpp files that only needed it for MRDOCS_ASSERT in the deleted functions.

The five private headers from src/lib/Support/Reflection/ are consolidated into a single public include/mrdocs/Support/Reflection.hpp. Shared type traits (is_optional, is_vector) move to the existing Support/TypeTraits.hpp. The tag_invoke overloads from the centralized Reflection.cpp are distributed into per-type .cpp files. The src/lib/Support/Reflection/ directory is deleted entirely.

gennaroprota force-pushed the refactor/switch_to_custom_reflection branch 9 times, most recently from 33415f8 to 8488bb2 Compare March 24, 2026 09:15

gennaroprota changed the title ~~refactor: switch to custom reflection (mrdocs::describe)~~ refactor: switch to custom reflection (MrDocs.Describe) Mar 24, 2026

gennaroprota force-pushed the refactor/switch_to_custom_reflection branch 3 times, most recently from eb2cc4a to 59b60d5 Compare March 25, 2026 11:06

gennaroprota force-pushed the refactor/switch_to_custom_reflection branch 3 times, most recently from f464cdf to d79dd24 Compare March 26, 2026 09:42

gennaroprota changed the title ~~refactor: switch to custom reflection (MrDocs.Describe)~~ Switch to custom reflection (MrDocs.Describe) Mar 26, 2026

gennaroprota force-pushed the refactor/switch_to_custom_reflection branch 3 times, most recently from 8864258 to 8b25b3a Compare March 26, 2026 18:15

alandefreitas reviewed Mar 27, 2026

View reviewed changes

gennaroprota force-pushed the refactor/switch_to_custom_reflection branch from 8b25b3a to 5df1a0b Compare March 27, 2026 16:36

gennaroprota added 3 commits March 27, 2026 17:58

gennaroprota force-pushed the refactor/switch_to_custom_reflection branch from 5df1a0b to 937aab7 Compare March 27, 2026 16:59

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