use Base.@show for the Compiler.jl standard library

[aviatesk]

Since Base.@show is much useful than Base.Compiler.@show.

[Keno]

isdefined(Base, :var"@show")?

[aviatesk]

Currently, we’re using isdefined(Base, :end_base_include) for bootstrapping/stdlib switching, so I thought this approach would be more consistent.
Also, I think what we’re essentially branching on here is not the definedness of Base.@show, but whether the entire show system in Base is available, so I feel like using isdefined(Base, :end_base_include) might be the better approach?

[Keno]

I guess we do need to know whether the show machinery is available in the world age that the compiler runs, though I do think they are largely equivalent. There is a definite reason to use end_base_include in the include code in particular, because that's the point at which the semantics of include change. I guess the other alternative would be to not have a Compiler-private version of @show at all, but instead have a bootstrap definition in Base that we erase later. That way, the compiler doesn't need special logic, it just picks up whatever version of @show happens to be in Base at loading time. I think I like that version best because it conceivably make the Compiler loadable on a stripped-down version of Base, but of course we aren't doing any of that right now.

[aviatesk]

Do you mean something like this?

diff --git a/Compiler/src/Compiler.jl b/Compiler/src/Compiler.jl
index aedda16573..3308bcf442 100644
--- a/Compiler/src/Compiler.jl
+++ b/Compiler/src/Compiler.jl
@@ -66,7 +66,7 @@ using Base: Ordering, vect, EffectsOverride, BitVector, @_gc_preserve_begin, @_g
     get_nospecializeinfer_sig, tls_world_age, uniontype_layout, kwerr,
     moduleroot, is_file_tracked, decode_effects_override, lookup_binding_partition,
     is_some_imported, binding_kind, is_some_guard, is_some_const_binding, partition_restriction,
-    BINDING_KIND_GLOBAL, structdiff
+    BINDING_KIND_GLOBAL, structdiff, @show
 using Base.Order
 import Base: getindex, setindex!, length, iterate, push!, isempty, first, convert, ==,
     copy, popfirst!, in, haskey, resize!, copy!, append!, last, get!, size,
@@ -137,20 +137,6 @@ if length(ARGS) > 2 && ARGS[2] === "--buildsettings"
 end
 end
 
-if !isdefined(Base, :end_base_include)
-    macro show(ex...)
-        blk = Expr(:block)
-        for s in ex
-            push!(blk.args, :(println(stdout, $(QuoteNode(s)), " = ",
-                                              begin local value = $(esc(s)) end)))
-        end
-        isempty(ex) || push!(blk.args, :value)
-        blk
-    end
-else
-    using Base: @show
-end
-
 include("cicache.jl")
 include("methodtable.jl")
 include("effects.jl")
diff --git a/base/Base_compiler.jl b/base/Base_compiler.jl
index b2633c25ee..5a1199e539 100644
--- a/base/Base_compiler.jl
+++ b/base/Base_compiler.jl
@@ -145,14 +145,21 @@ eval(m::Module, x) = Core.eval(m, x)
 include("exports.jl")
 include("public.jl")
 
-if false
-    # simple print definitions for debugging. enable these if something
-    # goes wrong during bootstrap before printing code is available.
-    # otherwise, they just just eventually get (noisily) overwritten later
-    global show, print, println
-    show(io::IO, x) = Core.show(io, x)
-    print(io::IO, a...) = Core.print(io, a...)
-    println(io::IO, x...) = Core.println(io, x...)
+# simple print definitions for debugging. enable these if something
+# goes wrong during bootstrap before printing code is available.
+# otherwise, they just eventually get (noisily) overwritten later
+global show, print, println
+show(io::IO, x) = Core.show(io, x)
+print(io::IO, a...) = Core.print(io, a...)
+println(io::IO, x...) = Core.println(io, x...)
+macro show(ex...)
+    blk = Expr(:block)
+    for s in ex
+        push!(blk.args, :(println(stdout, $(QuoteNode(s)), " = ",
+                                          begin local value = $(esc(s)) end)))
+    end
+    isempty(ex) || push!(blk.args, :value)
+    blk
 end
 
 """

As you’ve already mentioned in your comment, the noisy warnings are a bit concerning.