allow passing command line flags to compilecache. (#53316)

Pkg right now has to start a separate process to run precompilation for
the test environment which is annoying for multiple reasons

Corresponding Pkg PR: JuliaLang/Pkg.jl#3792

base/loading.jl

@@ -2447,7 +2447,7 @@ end
 
 const PRECOMPILE_TRACE_COMPILE = Ref{String}()
 function create_expr_cache(pkg::PkgId, input::String, output::String, output_o::Union{Nothing, String},
- concrete_deps::typeof(_concrete_dependencies), internal_stderr::IO = stderr, internal_stdout::IO = stdout)
+ concrete_deps::typeof(_concrete_dependencies), flags::Cmd=``, internal_stderr::IO = stderr, internal_stdout::IO = stdout)
  @nospecialize internal_stderr internal_stdout
  rm(output, force=true) # Remove file if it exists
  output_o === nothing || rm(output_o, force=true)
@@ -2503,6 +2503,7 @@ function create_expr_cache(pkg::PkgId, input::String, output::String, output_o::
  io = open(pipeline(addenv(`$(julia_cmd(;cpu_target)::Cmd) $(opts)
  --startup-file=no --history-file=no --warn-overwrite=yes
  --color=$(have_color === nothing ? "auto" : have_color ? "yes" : "no")
+ $flags
  $trace
  -`,
  "OPENBLAS_NUM_THREADS" => 1,
@@ -2570,17 +2571,17 @@ This can be used to reduce package load times. Cache files are stored in
 `DEPOT_PATH[1]/compiled`. See [Module initialization and precompilation](@ref)
 for important notes.
 """
-function compilecache(pkg::PkgId, internal_stderr::IO = stderr, internal_stdout::IO = stdout; reasons::Union{Dict{String,Int},Nothing}=Dict{String,Int}())
+function compilecache(pkg::PkgId, internal_stderr::IO = stderr, internal_stdout::IO = stdout; flags::Cmd=``, reasons::Union{Dict{String,Int},Nothing}=Dict{String,Int}())
  @nospecialize internal_stderr internal_stdout
  path = locate_package(pkg)
  path === nothing && throw(ArgumentError("$(repr("text/plain", pkg)) not found during precompilation"))
- return compilecache(pkg, path, internal_stderr, internal_stdout; reasons)
+ return compilecache(pkg, path, internal_stderr, internal_stdout; flags, reasons)
 end
 
 const MAX_NUM_PRECOMPILE_FILES = Ref(10)
 
 function compilecache(pkg::PkgId, path::String, internal_stderr::IO = stderr, internal_stdout::IO = stdout,
- keep_loaded_modules::Bool = true; reasons::Union{Dict{String,Int},Nothing}=Dict{String,Int}())
+ keep_loaded_modules::Bool = true; flags::Cmd=``, reasons::Union{Dict{String,Int},Nothing}=Dict{String,Int}())
 
  @nospecialize internal_stderr internal_stdout
  # decide where to put the resulting cache file
@@ -2618,7 +2619,7 @@ function compilecache(pkg::PkgId, path::String, internal_stderr::IO = stderr, in
  close(tmpio_o)
  close(tmpio_so)
  end
- p = create_expr_cache(pkg, path, tmppath, tmppath_o, concrete_deps, internal_stderr, internal_stdout)
+ p = create_expr_cache(pkg, path, tmppath, tmppath_o, concrete_deps, flags, internal_stderr, internal_stdout)
 
  if success(p)
  if cache_objects
@@ -3627,5 +3628,5 @@ end
 
 precompile(include_package_for_output, (PkgId, String, Vector{String}, Vector{String}, Vector{String}, typeof(_concrete_dependencies), Nothing))
 precompile(include_package_for_output, (PkgId, String, Vector{String}, Vector{String}, Vector{String}, typeof(_concrete_dependencies), String))
-precompile(create_expr_cache, (PkgId, String, String, String, typeof(_concrete_dependencies), IO, IO))
-precompile(create_expr_cache, (PkgId, String, String, Nothing, typeof(_concrete_dependencies), IO, IO))
+precompile(create_expr_cache, (PkgId, String, String, String, typeof(_concrete_dependencies), IO, IO, Cmd))
+precompile(create_expr_cache, (PkgId, String, String, Nothing, typeof(_concrete_dependencies), IO, IO, Cmd))

test/precompile.jl

@@ -1986,6 +1986,23 @@ precompile_test_harness("Issue #50538") do load_path
  @test !isdefined(I50538, :undefglobal)
 end
 
+precompile_test_harness("Test flags") do load_path
+ write(joinpath(load_path, "TestFlags.jl"),
+ """
+ module TestFlags
+ end
+ """)
+ ji, ofile = Base.compilecache(Base.PkgId("TestFlags"); flags=`--check-bounds=no -O3`)
+ @show ji, ofile
+ open(ji, "r") do io
+ Base.isvalid_cache_header(io)
+ _, _, _, _, _, _, _, flags = Base.parse_cache_header(io, ji)
+ cacheflags = Base.CacheFlags(flags)
+ @test cacheflags.check_bounds == 2
+ @test cacheflags.opt_level == 3
+ end
+end
+
 empty!(Base.DEPOT_PATH)
 append!(Base.DEPOT_PATH, original_depot_path)
 empty!(Base.LOAD_PATH)