Source generator: compiled companion NodeSet support and base-qualified NodeState emission

[marcschier]

Improves the OPC UA model source generator so it can source-generate compiled companion NodeSet2 models (for example an OPC companion spec such as Robotics/IA, or the OpenUSD binding model), and hardens the emitted NodeState/NodeManager code. The change is confined to the generator (tools/Opc.Ua.SourceGeneration*) and adds no runtime API surface.

Resolving standard types from referenced metadata. A new OpcUaStateTypeIndex collects the simple names of the standard Opc.Ua.*State classes (node-state and method-state) available in the compilation, including referenced assemblies such as Opc.Ua.Core. Wired through ModelCompilation and ModelSourceGenerator, it lets a companion model resolve standard (ns=0) class names from the referenced Core(.Types) metadata instead of inferring them.

Standard method-state fallback (interim, #4060). When a compiled NodeSet instantiates a standard type that carries methods (e.g. a FileDirectoryType Delete instance), the default naming can compute an Opc.Ua.*MethodState name that Core never emits. StandardMethodStateFallback is an ambient, execution-context-scoped policy that degrades such an unresolved global::Opc.Ua.*MethodState reference to the base global::Opc.Ua.MethodState - only when the typed class is neither declared by the current pass nor present in the compilation, keyed on the exact Opc.Ua namespace, and never applied in the Stack pass that builds Core.Types. This is the scoped interim workaround tracked by #4060; the proper upstream fix is a name-resolution step that makes it unnecessary.

Base-qualified attribute writes. The generator now emits base-qualified writes - ((global::Opc.Ua.NodeState)state).X = ... - for the base NodeState members NodeId, SymbolicName, BrowseName, AccessRestrictions, ReleaseStatus, Categories, Specification and Description. When a generated subclass shadows one of these with a strongly-typed new property, an unqualified write would target the shadow rather than the base setter; base-qualifying guarantees it reaches NodeState. For non-shadowing types it is a redundant-but-safe upcast, so existing generated consumers compile unchanged.

Supporting changes. The emitted NodeId/ExpandedNodeId static declarations are now global::-qualified on their namespace prefix to avoid namespace-collision ambiguities, with related adjustments in NodeStateGenerator, ModelDesignExtensions and FluentBuilderGenerator. Opc.Ua.Types additionally exposes internals to Opc.Ua.Core.Encoders.Tests.

Tests and validation. New StandardMethodStateFallbackTests cover the fallback policy, and the NodeState/NodeManager golden-string tests are updated to expect the base-qualified emission. The change set is exercised by the Opc.Ua.SourceGeneration.Core generator test suite on net10.0 and net48, and by regenerating and building Opc.Ua.Core.Types across the full target-framework set (net472 through net10.0); PR CI runs the complete build/test matrix.

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Pull request overview

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This PR updates the OPC UA model source generator to emit base-qualified writes to NodeState members (avoiding issues when generated subclasses shadow those members), and to global::-qualify emitted NodeId/ExpandedNodeId declarations to prevent namespace collisions.

Changes:

• Base-qualify generated assignments to NodeState properties in NodeState/NodeManager factories.
• global::-qualify namespace prefixes in emitted NodeId/ExpandedNodeId declarations.
• Update golden-string tests to assert the new emitted code forms.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tools/Opc.Ua.SourceGeneration.Core/Generators/NodeStateTemplates.cs	Emits base-qualified writes in templates (factory output).
tools/Opc.Ua.SourceGeneration.Core/Generators/NodeStateGenerator.cs	Base-qualifies additional emitted property assignments (ReleaseStatus/Categories/etc.).
tools/Opc.Ua.SourceGeneration.Core/Generators/NodeIdTemplates.cs	global::-qualifies namespace prefix usage in emitted declarations.
tests/Opc.Ua.SourceGeneration.Core.Tests/Generators/NodeStateGeneratorTests.cs	Updates assertions for base-qualified NodeId/BrowseName writes.
tests/Opc.Ua.SourceGeneration.Core.Tests/Generators/NodeManagerGeneratorTests.cs	Updates assertions for base-qualified AccessRestrictions writes.

[koepalex]

LGTM

[codecov]

Codecov Report

❌ Patch coverage is 93.62416% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.59%. Comparing base (12f770b) to head (26275ca).
⚠️ Report is 20 commits behind head on master.

Files with missing lines	Patch %	Lines
...eration.Core/Schema/StandardMethodStateFallback.cs	77.50%	4 Missing and 5 partials ⚠️
...ols/Opc.Ua.SourceGeneration/OpcUaStateTypeIndex.cs	71.42%	2 Missing and 4 partials ⚠️
...neration.Core/Generators/FluentBuilderGenerator.cs	76.92%	2 Missing and 1 partial ⚠️
...rceGeneration.Core/Schema/ModelDesignExtensions.cs	85.71%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4063      +/-   ##
==========================================
- Coverage   73.86%   73.59%   -0.28%     
==========================================
  Files        1345     1347       +2     
  Lines      180038   180218     +180     
  Branches    31678    31704      +26     
==========================================
- Hits       132993   132632     -361     
- Misses      36290    36863     +573     
+ Partials    10755    10723      -32     

Files with missing lines	Coverage Δ
...ourceGeneration.Core/Generators/NodeIdTemplates.cs	100.00% <100.00%> (ø)
...ceGeneration.Core/Generators/NodeStateGenerator.cs	86.96% <100.00%> (+0.03%)	⬆️
...ceGeneration.Core/Generators/NodeStateTemplates.cs	100.00% <100.00%> (ø)
tools/Opc.Ua.SourceGeneration/ModelCompilation.cs	69.68% <100.00%> (+0.49%)	⬆️
...ls/Opc.Ua.SourceGeneration/ModelSourceGenerator.cs	100.00% <100.00%> (ø)
...rceGeneration.Core/Schema/ModelDesignExtensions.cs	86.34% <85.71%> (-0.02%)	⬇️
...neration.Core/Generators/FluentBuilderGenerator.cs	85.92% <76.92%> (-0.13%)	⬇️
...ols/Opc.Ua.SourceGeneration/OpcUaStateTypeIndex.cs	71.42% <71.42%> (ø)
...eration.Core/Schema/StandardMethodStateFallback.cs	77.50% <77.50%> (ø)

... and 48 files with indirect coverage changes

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