fix: skip explicit constructors in universal codegen

[gmelodie]

Summary

logos-cpp-generator's impl-header parser skips constructors via a regex anchored at ^\s*~?<Class>\s*\(, which doesn't match explicit <Class>(. When a module's impl class declares its constructor with explicit (e.g. explicit Libp2pModuleImpl(const Libp2pModuleOptions& opts = {});), the constructor leaks through as a regular method and the generated Qt glue emits:

QVariant Libp2pModuleImpl() { return m_impl.Libp2pModuleImpl(); }
...
Libp2pModuleImpl m_impl;

The method name shadows the type name, so the trailing Libp2pModuleImpl m_impl; field declaration fails with 'Libp2pModuleImpl' does not name a type, and every subsequent reference to m_impl reports was not declared in this scope. This shows up downstream as a nix flake check failure in logos-libp2p-module on the openmetrics scaffold branch.

Workaround: copy the impl header to a temp dir, strip explicit from the ctor line, and feed the sanitized copy to --from-header. --impl-header keeps the original filename so the generated #include still resolves to the real header at compile time. No source files are mutated and the original explicit semantics are preserved everywhere else in the build.

The real fix belongs in logos-cpp-sdk's impl_header_parser.cpp (the ctor regex should permit decl-specifiers); this is a stopgap until that lands.

[github-actions]

📊 External-library doc-test report

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