The task asks to refactor the Go switchStmt() predicate in go/ql/lib/semmle/go/controlflow/ControlFlowGraphShared.qll to adopt the shared CFG library's default switch handling. No code changes were made because the referenced predicate and file do not exist on this branch.

Findings

• Missing file — go/ql/lib/semmle/go/controlflow/ControlFlowGraphShared.qll is absent from this branch, from main (the PR base, f0576046), and from all available git history. The Go CFG directory only contains ControlFlowGraph.qll, ControlFlowGraphImpl.qll, BasicBlocks.qll, and IR.qll.
• No switchStmt() predicate — Go's switch CFG is built by a bespoke SwitchTree/CaseClauseTree mechanism in ControlFlowGraphImpl.qll (~lines 1076–2120) using Go's own ControlFlowTree framework.
• Go does not instantiate the shared CFG library — although codeql/controlflow is a declared dependency in go/ql/lib/qlpack.yml, the Go CFG is entirely hand-written. Java and C# do instantiate the shared library, where the generic Switch/Case handling lives (shared/controlflow/codeql/controlflow/ControlFlowGraph.qll).

Why this is blocked

The shared library's switch handling (Switch, Case, fallsThrough, getRankedCaseCfgOrder, and the isBefore/isAfter PreControlFlowNode machinery) is integral to the shared CFG construction framework. It cannot be adopted in isolation — it requires Go's CFG to first instantiate that framework. This points to a prerequisite migration branch (introducing ControlFlowGraphShared.qll and wiring Go to the shared CFG) that is not present here.

Open questions for the reviewer

• Is there a base/feature branch carrying the in-progress shared-CFG migration that this PR should stack on? If so, the switchStmt() refactor belongs there.
• Otherwise, should this PR bootstrap the shared-CFG instantiation for Go? That is a substantial change beyond a surgical edit and warrants scope confirmation before proceeding.

No ControlFlowGraphShared.qll was fabricated, as doing so would produce code that does not compile against the current tree.

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