Go was the last language with its own bespoke SSA implementation. This migrates it to the shared codeql.ssa.Ssa library, consistent with C#, Java, Ruby, Rust, and Swift.

Key changes

• go/ql/lib/qlpack.yml: Add codeql/ssa: ${workspace} dependency.

• BasicBlocks.qll: Add module Cfg implements BB::CfgSig<Location> — the CFG adapter required by the shared library.

• SsaImpl.qll (complete rewrite):

  • Keeps private Go-specific predicates (defAt, useAt, mayCapture, assignedThroughClosure).
  • Implements SsaInput implements SsaImplCommon::InputSig<Location, BasicBlock> feeding variableWrite (certain = explicit def, uncertain = capture) and variableRead.
  • Adds a synthetic uncertain read at function-exit for captured variables to preserve liveness for variables used only in nested functions — preserving the old v.isCaptured() short-circuit.
  • Instantiates via SsaImplCommon::Make<Location, BasicBlocks::Cfg, SsaInput> as Impl.
  • Exports type aliases (Definition, WriteDefinition, UncertainWriteDefinition, PhiNode) and cached predicates (ssaDefReachesRead, phiHasInputFromBlock, firstUse, adjacentUseUse).

• SSA.qll (updated public API):

  • SsaVariable, SsaDefinition now extend the shared Definition instead of a local newtype.
  • SsaExplicitDefinition extends SsaDefinition, WriteDefinition
  • SsaVariableCapture extends SsaImplicitDefinition, UncertainWriteDefinition
  • SsaPhiNode extends SsaPseudoDefinition, PhiNode
  • All toString() formats match the prior output ("definition of x", "capture variable x", "x = phi(def@L:C, ...)") so test expectations are unchanged. Removed the definesAt(bb, idx, v) compatibility wrapper (no external callers) and the now-redundant getBasicBlock() override (it's final in the shared library).

Created from VS Code.

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