allow the Compiler.jl stdlib to be installed on older version of Julia

Compiler/Project.toml

@@ -1,3 +1,3 @@
 name = "Compiler"
 uuid = "807dbc54-b67e-4c79-8afb-eafe4df6f2e1"
-version = "0.0.1"
+version = "0.0.2"

Compiler/src/Compiler.jl

@@ -1,15 +1,28 @@
 # This file is a part of Julia. License is MIT: https://julialang.org/license
 
+if isdefined(Base, :end_base_include) && !isdefined(Base, :Compiler)
+
+# Define a dummy `Compiler` module to make it installable even on Julia versions where
+# Compiler.jl is not available as a standard library.
+@eval module Compiler
+    function __init__()
+        println("""
+        The `Compiler` standard library is not available for this version of Julia.
+        Use Julia version `v"1.12.0-DEV.1581"` or later.
+        """)
+    end
+end
+
 # When generating an incremental precompile file, we first check whether we
 # already have a copy of this *exact* code in the system image. If so, we
 # simply generates a pkgimage that has the dependency edges we recorded in
 # the system image and simply returns that copy of the compiler. If not,
 # we proceed to load/precompile this as an ordinary package.
-if isdefined(Base, :generating_output) && Base.generating_output(true) &&
+elseif (isdefined(Base, :generating_output) && Base.generating_output(true) &&
         Base.samefile(joinpath(Sys.BINDIR, Base.DATAROOTDIR, Base._compiler_require_dependencies[1][2]), @eval @__FILE__) &&
         !Base.any_includes_stale(
             map(Base.compiler_chi, Base._compiler_require_dependencies),
-            "sysimg", nothing)
+            "sysimg", nothing))
 
     Base.prepare_compiler_stub_image!()
     append!(Base._require_dependencies, map(Base.expand_compiler_path, Base._compiler_require_dependencies))
@@ -167,7 +180,7 @@ include("optimize.jl")
 include("bootstrap.jl")
 include("reflection_interface.jl")
 
-if isdefined(Base, :IRShow)
+if isdefined(Base, :end_base_include)
     @eval module IRShow
         using ..Compiler: Compiler
         # During bootstrap, Base will later include this into its own "IRShow module"

Compiler/src/ssair/show.jl

@@ -1135,3 +1135,12 @@ function Base.show(io::IO, tinf::Timings.Timing)
 end
 
 @specialize
+
+const __debuginfo = Dict{Symbol, Any}(
+    # :full => src -> statementidx_lineinfo_printer(src), # and add variable slot information
+    :source => src -> statementidx_lineinfo_printer(src),
+    # :oneliner => src -> statementidx_lineinfo_printer(PartialLineInfoPrinter, src),
+    :none => src -> lineinfo_disabled,
+    )
+const default_debuginfo = Ref{Symbol}(:none)
+debuginfo(sym) = sym === :default ? default_debuginfo[] : sym

base/show.jl

@@ -2824,15 +2824,6 @@ end
 module IRShow
     using ..Compiler: Compiler
     Base.include(IRShow, Base.strcat(Base.BUILDROOT, "../usr/share/julia/Compiler/src/ssair/show.jl"))
-
-    const __debuginfo = Dict{Symbol, Any}(
-        # :full => src -> statementidx_lineinfo_printer(src), # and add variable slot information
-        :source => src -> statementidx_lineinfo_printer(src),
-        # :oneliner => src -> statementidx_lineinfo_printer(PartialLineInfoPrinter, src),
-        :none => src -> lineinfo_disabled,
-        )
-    const default_debuginfo = Ref{Symbol}(:none)
-    debuginfo(sym) = sym === :default ? default_debuginfo[] : sym
 end
 
 function show(io::IO, src::CodeInfo; debuginfo::Symbol=:source)