complete the tests for Compiler.jl as the stdlib.

With #56632, Compiler.jl as the stdlib can now be tested.
However, the PR was incomplete, and when tests are actually run on
`Compiler`, which is `!== Base.Compiler`, various errors occur,
including issues caused by #56647.

This commit resolves all these issues:
- manage the code for loading `Compiler` in `setup_Compiler.jl`,
  ensuring that the stdlib version of `Compiler` is loaded when
  `@activate Compiler` is used beforehand
- replace `Base.IRShow` with `Compiler.IRShow`
- test `Base.Compiler.return_type` instead of `Compiler.return_type`

This was split off from #56636.

Compiler/src/ssair/verify.jl

@@ -104,7 +104,7 @@ function verify_ir(ir::IRCode, print::Bool=true,
         error_args = Any["IR verification failed."]
         if isdefined(Core, :Main) && isdefined(Core.Main, :Base)
             # ensure we use I/O that does not yield, as this gets called during compilation
-            firstline = invokelatest(Core.Main.Base.IRShow.debuginfo_firstline, ir.debuginfo)
+            firstline = invokelatest(IRShow.debuginfo_firstline, ir.debuginfo)
         else
             firstline = nothing
         end

Compiler/test/AbstractInterpreter.jl

@@ -2,14 +2,6 @@
 
 using Test
 
-if !@isdefined(Compiler)
-    if Base.identify_package("Compiler") === nothing
-        import Base.Compiler: Compiler
-    else
-        import Compiler
-    end
-end
-
 include("irutils.jl")
 include("newinterp.jl")
 

Compiler/test/EAUtils.jl

@@ -2,13 +2,7 @@ module EAUtils
 
 export code_escapes, @code_escapes, __clear_cache!
 
-if !@isdefined(Compiler)
-    if Base.identify_package("Compiler") === nothing
-        import Base.Compiler: Compiler
-    else
-        import Compiler
-    end
-end
+include("setup_Compiler.jl")
 
 using ..EscapeAnalysis
 const EA = EscapeAnalysis
@@ -267,22 +261,22 @@ end
 
 function print_with_info(preprint, postprint, io::IO, ir::IRCode, source::Bool)
     io = IOContext(io, :displaysize=>displaysize(io))
-    used = Base.IRShow.stmts_used(io, ir)
+    used = Compiler.IRShow.stmts_used(io, ir)
     if source
         line_info_preprinter = function (io::IO, indent::String, idx::Int)
-            r = Base.IRShow.inline_linfo_printer(ir)(io, indent, idx)
+            r = Compiler.IRShow.inline_linfo_printer(ir)(io, indent, idx)
             idx ≠ 0 && preprint(io, idx)
             return r
         end
     else
-        line_info_preprinter = Base.IRShow.lineinfo_disabled
+        line_info_preprinter = Compiler.IRShow.lineinfo_disabled
     end
-    line_info_postprinter = Base.IRShow.default_expr_type_printer
+    line_info_postprinter = Compiler.IRShow.default_expr_type_printer
     preprint(io)
     bb_idx_prev = bb_idx = 1
     for idx = 1:length(ir.stmts)
         preprint(io, idx)
-        bb_idx = Base.IRShow.show_ir_stmt(io, ir, idx, line_info_preprinter, line_info_postprinter, ir.sptypes, used, ir.cfg, bb_idx)
+        bb_idx = Compiler.IRShow.show_ir_stmt(io, ir, idx, line_info_preprinter, line_info_postprinter, ir.sptypes, used, ir.cfg, bb_idx)
         postprint(io, idx, bb_idx != bb_idx_prev)
         bb_idx_prev = bb_idx
     end

Compiler/test/codegen.jl

@@ -5,14 +5,9 @@
 using Random
 using InteractiveUtils
 using Libdl
+using Test
 
-if !@isdefined(Compiler)
-    if Base.identify_package("Compiler") === nothing
-        import Base.Compiler: Compiler
-    else
-        import Compiler
-    end
-end
+include("setup_Compiler.jl")
 
 const opt_level = Base.JLOptions().opt_level
 const coverage = (Base.JLOptions().code_coverage > 0) || (Base.JLOptions().malloc_log > 0)

Compiler/test/compact.jl

@@ -1,10 +1,8 @@
-if !@isdefined(Compiler)
-    if Base.identify_package("Compiler") === nothing
-        import Base.Compiler: Compiler
-    else
-        import Compiler
-    end
-end
+# This file is a part of Julia. License is MIT: https://julialang.org/license
+
+using Test
+
+include("irutils.jl")
 
 using .Compiler: IncrementalCompact, insert_node_here!, finish,
     NewInstruction, verify_ir, ReturnNode, SSAValue

Compiler/test/contextual.jl

@@ -2,14 +2,7 @@
 
 # N.B.: This file is also run from interpreter.jl, so needs to be standalone-executable
 using Test
-
-if !@isdefined(Compiler)
-    if Base.identify_package("Compiler") === nothing
-        import Base.Compiler: Compiler
-    else
-        import Compiler
-    end
-end
+include("setup_Compiler.jl")
 
 # Cassette
 # ========

Compiler/test/datastructures.jl

@@ -1,12 +1,6 @@
-using Test
+# This file is a part of Julia. License is MIT: https://julialang.org/license
 
-if !@isdefined(Compiler)
-    if Base.identify_package("Compiler") === nothing
-        import Base.Compiler: Compiler
-    else
-        import Compiler
-    end
-end
+include("setup_Compiler.jl")
 
 @testset "CachedMethodTable" begin
     # cache result should be separated per `limit` and `sig`

Compiler/test/effects.jl

@@ -1,3 +1,5 @@
+# This file is a part of Julia. License is MIT: https://julialang.org/license
+
 using Test
 include("irutils.jl")
 

Compiler/test/inference.jl

@@ -1,9 +1,11 @@
 # This file is a part of Julia. License is MIT: https://julialang.org/license
 
+using Test
+
 include("irutils.jl")
 
 # tests for Compiler correctness and precision
-import .Compiler: Const, Conditional, ⊑, ReturnNode, GotoIfNot
+using .Compiler: Conditional, ⊑
 isdispatchelem(@nospecialize x) = !isa(x, Type) || Compiler.isdispatchelem(x)
 
 using Random, Core.IR
@@ -823,7 +825,7 @@ end
 
 # Issue 19641
 foo19641() = let a = 1.0
-    Compiler.return_type(x -> x + a, Tuple{Float64})
+    Base.Compiler.return_type(x -> x + a, Tuple{Float64})
 end
 @inferred foo19641()
 
@@ -977,15 +979,15 @@ test_no_apply(::Any) = true
 
 # issue #20033
 # check return_type_tfunc for calls where no method matches
-bcast_eltype_20033(f, A) = Compiler.return_type(f, Tuple{eltype(A)})
+bcast_eltype_20033(f, A) = Base.Compiler.return_type(f, Tuple{eltype(A)})
 err20033(x::Float64...) = prod(x)
 @test bcast_eltype_20033(err20033, [1]) === Union{}
 @test Base.return_types(bcast_eltype_20033, (typeof(err20033), Vector{Int},)) == Any[Type{Union{}}]
 # return_type on builtins
-@test Compiler.return_type(tuple, Tuple{Int,Int8,Int}) === Tuple{Int,Int8,Int}
+@test Base.Compiler.return_type(tuple, Tuple{Int,Int8,Int}) === Tuple{Int,Int8,Int}
 
 # issue #21088
-@test Compiler.return_type(typeof, Tuple{Int}) == Type{Int}
+@test Base.Compiler.return_type(typeof, Tuple{Int}) == Type{Int}
 
 # Inference of constant svecs
 @eval fsvecinf() = $(QuoteNode(Core.svec(Tuple{Int,Int}, Int)))[1]
@@ -1535,7 +1537,7 @@ let nfields_tfunc(@nospecialize xs...) =
     @test sizeof_nothrow(String)
     @test !sizeof_nothrow(Type{String})
     @test sizeof_tfunc(Type{Union{Int64, Int32}}) == Const(Core.sizeof(Union{Int64, Int32}))
-    let PT = Core.PartialStruct(Base.Compiler.fallback_lattice, Tuple{Int64,UInt64}, Any[Const(10), UInt64])
+    let PT = Core.PartialStruct(Compiler.fallback_lattice, Tuple{Int64,UInt64}, Any[Const(10), UInt64])
         @test sizeof_tfunc(PT) === Const(16)
         @test nfields_tfunc(PT) === Const(2)
         @test sizeof_nothrow(PT)
@@ -1721,7 +1723,7 @@ g_test_constant() = (f_constant(3) == 3 && f_constant(4) == 4 ? true : "BAD")
 f_pure_add() = (1 + 1 == 2) ? true : "FAIL"
 @test @inferred f_pure_add()
 
-import Core: Const
+using Core: Const
 mutable struct ARef{T}
     @atomic x::T
 end
@@ -1762,7 +1764,7 @@ let getfield_tfunc(@nospecialize xs...) =
     @test getfield_tfunc(ARef{Int},Const(:x),Bool,Bool) === Union{}
 end
 
-import .Compiler: Const
+using Core: Const
 mutable struct XY{X,Y}
     x::X
     y::Y
@@ -2235,7 +2237,7 @@ end
     end |> only == Int
     # the `fargs = nothing` edge case
     @test Base.return_types((Any,)) do a
-        Compiler.return_type(invoke, Tuple{typeof(ispositive), Type{Tuple{Any}}, Any})
+        Base.Compiler.return_type(invoke, Tuple{typeof(ispositive), Type{Tuple{Any}}, Any})
     end |> only == Type{Bool}
 
     # `InterConditional` handling: `abstract_call_opaque_closure`
@@ -2765,10 +2767,9 @@ end |> only === Int
 
 # `apply_type_tfunc` accuracy for constrained type construction
 # https://github.com/JuliaLang/julia/issues/47089
-import Core: Const
-import .Compiler: apply_type_tfunc
 struct Issue47089{A<:Number,B<:Number} end
-let 𝕃 = Compiler.fallback_lattice
+let apply_type_tfunc = Compiler.apply_type_tfunc
+    𝕃 = Compiler.fallback_lattice
     A = Type{<:Integer}
     @test apply_type_tfunc(𝕃, Const(Issue47089), A, A) <: (Type{Issue47089{A,B}} where {A<:Integer, B<:Integer})
     @test apply_type_tfunc(𝕃, Const(Issue47089), Const(Int), Const(Int), Const(Int)) === Union{}
@@ -3324,8 +3325,8 @@ _rttf_test(::Int16) = 0
 _rttf_test(::Int32) = 0
 _rttf_test(::Int64) = 0
 _rttf_test(::Int128) = 0
-_call_rttf_test() = Compiler.return_type(_rttf_test, Tuple{Any})
-@test Compiler.return_type(_rttf_test, Tuple{Any}) === Int
+_call_rttf_test() = Base.Compiler.return_type(_rttf_test, Tuple{Any})
+@test Base.Compiler.return_type(_rttf_test, Tuple{Any}) === Int
 @test _call_rttf_test() === Int
 
 f_with_Type_arg(::Type{T}) where {T} = T
@@ -3379,9 +3380,9 @@ struct FooPartial
     b::Int
     c::Int
 end
-let PT1 = PartialStruct(Base.Compiler.fallback_lattice, FooPartial, Any[Const(1), Const(2), Int]),
-    PT2 = PartialStruct(Base.Compiler.fallback_lattice, FooPartial, Any[Const(1), Int, Int]),
-    PT3 = PartialStruct(Base.Compiler.fallback_lattice, FooPartial, Any[Const(1), Int, Const(3)])
+let PT1 = PartialStruct(Compiler.fallback_lattice, FooPartial, Any[Const(1), Const(2), Int]),
+    PT2 = PartialStruct(Compiler.fallback_lattice, FooPartial, Any[Const(1), Int, Int]),
+    PT3 = PartialStruct(Compiler.fallback_lattice, FooPartial, Any[Const(1), Int, Const(3)])
 
     @test PT1 ⊑ PT2
     @test !(PT1 ⊑ PT3) && !(PT2 ⊑ PT1)
@@ -4554,7 +4555,8 @@ end |> only == Tuple{Int,Int}
 end |> only == Int
 
 # form PartialStruct for mutables with `const` field
-import .Compiler: Const, ⊑
+using Core: Const
+using .Compiler: ⊑
 mutable struct PartialMutable{S,T}
     const s::S
     t::T
@@ -4787,7 +4789,7 @@ end
 # at top level.
 @test let
     Base.Experimental.@force_compile
-    Compiler.return_type(+, NTuple{2, Rational})
+    Base.Compiler.return_type(+, NTuple{2, Rational})
 end == Rational
 
 # vararg-tuple comparison within `Compiler.PartialStruct`
@@ -5185,9 +5187,9 @@ end |> only === Tuple{Int,Symbol}
     end
 end) == Type{Nothing}
 
-# Test that Compiler.return_type inference works for the 1-arg version
+# Test that Base.Compiler.return_type inference works for the 1-arg version
 @test Base.return_types() do
-    Compiler.return_type(Tuple{typeof(+), Int, Int})
+    Base.Compiler.return_type(Tuple{typeof(+), Int, Int})
 end |> only == Type{Int}
 
 # Test that NamedTuple abstract iteration works for PartialStruct/Const
@@ -5700,7 +5702,8 @@ let x = 1, _Any = Any
 end
 
 # Issue #51927
-let 𝕃 = Compiler.fallback_lattice
+let apply_type_tfunc = Compiler.apply_type_tfunc
+    𝕃 = Compiler.fallback_lattice
     @test apply_type_tfunc(𝕃, Const(Tuple{Vararg{Any,N}} where N), Int) == Type{NTuple{_A, Any}} where _A
 end
 
@@ -5723,7 +5726,7 @@ end
 @eval function has_tuin()
     $(Expr(:throw_undef_if_not, :x, false))
 end
-@test Compiler.return_type(has_tuin, Tuple{}) === Union{}
+@test Base.infer_return_type(has_tuin, Tuple{}) === Union{}
 @test_throws UndefVarError has_tuin()
 
 function gen_tuin_from_arg(world::UInt, source, _, _)
@@ -5778,7 +5781,7 @@ end
 
 # We want to make sure that both this returns `Tuple` and that
 # it doesn't infinite loop inside inference.
-@test Compiler.return_type(gen_infinite_loop_ssa, Tuple{}) === Tuple
+@test Base.infer_return_type(gen_infinite_loop_ssa, Tuple{}) === Tuple
 
 # inference local cache lookup with extended lattice elements that may be transformed
 # by `matching_cache_argtypes`
@@ -5814,7 +5817,7 @@ function foo54341(a, b, c, d, args...)
 end
 bar54341(args...) = foo54341(4, args...)
 
-@test Compiler.return_type(bar54341, Tuple{Vararg{Int}}) === Int
+@test Base.infer_return_type(bar54341, Tuple{Vararg{Int}}) === Int
 
 # `PartialStruct` for partially initialized structs:
 struct PartiallyInitialized1
@@ -5951,7 +5954,7 @@ end
 # InterConditional rt with Vararg argtypes
 fcondvarargs(a, b, c, d) = isa(d, Int64)
 gcondvarargs(a, x...) = return fcondvarargs(a, x...) ? isa(a, Int64) : !isa(a, Int64)
-@test Compiler.return_type(gcondvarargs, Tuple{Vararg{Any}}) === Bool
+@test Base.infer_return_type(gcondvarargs, Tuple{Vararg{Any}}) === Bool
 
 # JuliaLang/julia#55627: argtypes check in `abstract_call_opaque_closure`
 issue55627_make_oc() = Base.Experimental.@opaque (x::Int) -> 2x
@@ -6098,4 +6101,4 @@ function func_swapglobal!_must_throw(x)
     swapglobal!(@__MODULE__, :swapglobal!_must_throw, x)
 end
 @test Base.infer_return_type(func_swapglobal!_must_throw, (Int,); interp=SwapGlobalInterp()) === Union{}
-@test !Base.Compiler.is_effect_free(Base.infer_effects(func_swapglobal!_must_throw, (Int,); interp=SwapGlobalInterp()) )
+@test !Compiler.is_effect_free(Base.infer_effects(func_swapglobal!_must_throw, (Int,); interp=SwapGlobalInterp()) )

Compiler/test/inline.jl

@@ -1857,7 +1857,7 @@ let i::Int, continue_::Bool
     ir = Compiler.ssa_inlining_pass!(ir, inlining, false)
     @test findfirst(isinvoke(:func_mul_int), ir.stmts.stmt) === nothing
     @test (i = findfirst(iscall((ir, Core.Intrinsics.mul_int)), ir.stmts.stmt)) !== nothing
-    lins = Base.IRShow.buildLineInfoNode(ir.debuginfo, nothing, i)
+    lins = Compiler.IRShow.buildLineInfoNode(ir.debuginfo, nothing, i)
     @test (continue_ = length(lins) == 2) # :multi_inlining1 -> :func_mul_int
     if continue_
         def1 = lins[1].method
@@ -1881,7 +1881,7 @@ let i::Int, continue_::Bool
     ir = Compiler.ssa_inlining_pass!(ir, inlining, false)
     @test findfirst(isinvoke(:func_mul_int), ir.stmts.stmt) === nothing
     @test (i = findfirst(iscall((ir, Core.Intrinsics.mul_int)), ir.stmts.stmt)) !== nothing
-    lins = Base.IRShow.buildLineInfoNode(ir.debuginfo, nothing, i)
+    lins = Compiler.IRShow.buildLineInfoNode(ir.debuginfo, nothing, i)
     @test_broken (continue_ = length(lins) == 3) # see TODO in `ir_inline_linetable!`
     if continue_
         def1 = lins[1].method

Compiler/test/interpreter_exec.jl

@@ -1,17 +1,11 @@
 # This file is a part of Julia. License is MIT: https://julialang.org/license
 
 # tests that interpreter matches codegen
+include("setup_Compiler.jl")
+
 using Test
 using Core.IR
 
-if !@isdefined(Compiler)
-    if Base.identify_package("Compiler") === nothing
-        import Base.Compiler: Compiler
-    else
-        import Compiler
-    end
-end
-
 # test that interpreter correctly handles PhiNodes (#29262)
 let m = Meta.@lower 1 + 1
     @assert Meta.isexpr(m, :thunk)

Compiler/test/invalidation.jl

@@ -104,7 +104,7 @@ begin
     let rt = only(Base.return_types(pr48932_callee, (Any,)))
         @test rt === Any
         effects = Base.infer_effects(pr48932_callee, (Any,))
-        @test Compiler.Effects(effects) == Compiler.Effects()
+        @test effects == Compiler.Effects()
     end
 
     # run inference on both `pr48932_caller` and `pr48932_callee`
@@ -171,7 +171,7 @@ begin take!(GLOBAL_BUFFER)
     let rt = only(Base.return_types(pr48932_callee_inferable, (Any,)))
         @test rt === Int
         effects = Base.infer_effects(pr48932_callee_inferable, (Any,))
-        @test Compiler.Effects(effects) == Compiler.Effects()
+        @test effects == Compiler.Effects()
     end
 
     # run inference on both `pr48932_caller` and `pr48932_callee`:
@@ -233,7 +233,7 @@ begin take!(GLOBAL_BUFFER)
     let rt = only(Base.return_types(pr48932_callee_inlined, (Any,)))
         @test rt === Any
         effects = Base.infer_effects(pr48932_callee_inlined, (Any,))
-        @test Compiler.Effects(effects) == Compiler.Effects()
+        @test effects == Compiler.Effects()
     end
 
     # run inference on `pr48932_caller_inlined` and `pr48932_callee_inlined`