Go: Use shared basic block lib

[owen-mc]

Use the shared library to instantiate basic blocks. This leads to a small number of breaking changes to member predicate names, as detailed in the change note.

I wasn't sure if ReachableBasicBlock and ReachableJoinBlock are really needed any more. Their main purpose seems to have been to avoid unnecessary calculations in the dominance frontier calculation and some SSA calculations. I will leave them for now - I imagine they'll disappear when we adopt the shared SSA library at some point in the future.

[Copilot]

Pull request overview

This pull request refactors the Go language's basic block implementation to use a shared basic blocks library from the CodeQL standard library, resulting in cleaner code and better consistency across languages.

Changes:

• Migrated BasicBlock class implementation from custom code to the shared codeql.controlflow.BasicBlock library
• Updated API across the codebase: renamed getRoot() to getScope(), added successor type parameters to getAPredecessor() and getASuccessor(), and replaced inDominanceFrontierOf() with inDominanceFrontier() with swapped arguments
• Added supporting infrastructure including the ControlFlowNode type alias and getOutcome() method for ConditionGuardNode

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
go/ql/lib/semmle/go/controlflow/BasicBlocks.qll	Replaced custom basic block implementation with shared library integration through Input module and BbImpl instantiation
go/ql/lib/semmle/go/dataflow/SsaImpl.qll	Updated API calls: getRoot() to getScope(), added _ parameter to successor/predecessor calls, and swapped inDominanceFrontierOf() arguments
go/ql/lib/semmle/go/dataflow/SSA.qll	Updated getRoot() to getScope() and added _ parameter to getAPredecessor()
go/ql/lib/semmle/go/controlflow/ControlFlowGraph.qll	Added getOutcome() method to ConditionGuardNode and ControlFlowNode type alias to support shared library integration
go/ql/src/Security/CWE-020/IncompleteHostnameRegexp.ql	Updated getAPredecessor() call to include _ parameter
go/ql/lib/qlpack.yml	Added dependency on codeql/controlflow library
go/ql/lib/change-notes/2026-01-28-shared-basic-block-library.md	Documented breaking changes from this refactoring

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[owen-mc]

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