Check with coverage off

.github/workflows/CI.yml

@@ -38,7 +38,10 @@ jobs:
             ${{ runner.os }}-
       - uses: julia-actions/julia-buildpkg@v1
       - uses: julia-actions/julia-runtest@v1
-      - name: Bounds check
+      - name: Coverage off  # `empty_func` test doesn't work as intended with `coverage=true`
+        if: ${{ matrix.os == 'ubuntu-latest' }}
+        run: julia --project -e 'using Pkg; Pkg.test("Cthulhu"; coverage=false)'
+      - name: Bounds/DCE check
         if: ${{ matrix.os == 'ubuntu-latest' }}
         run: julia --project --code-coverage -e 'using Pkg; Pkg.add(["Revise", "StaticArrays"]); cd("test"); include("runtests.jl")'
       - uses: julia-actions/julia-processcoverage@v1

src/Cthulhu.jl

@@ -186,6 +186,8 @@ function lookup(interp::CthulhuInterpreter, mi::MethodInstance, optimize::Bool)
             infos = ir.stmts.info
             slottypes = ir.argtypes
         else
+            # This doesn't showed up as covered, but it is (see the CI test with `coverage=false`).
+            # But with coverage on, the empty function body isn't empty due to :code_coverage_effect expressions.
             codeinf = nothing
             infos = []
             slottypes = Any[Base.unwrap_unionall(mi.specTypes).parameters...]