Define exports to throw informative error in Julia DEV versions (#688)

src/JET.jl

@@ -6,6 +6,19 @@ const JET_DEV_MODE = Preferences.@load_preference("JET_DEV_MODE", false)
 
 const JET_LOADABLE = JET_DEV_MODE || (get(VERSION.prerelease, 1, "") != "DEV")
 
+# exports
+# =======
+
+export
+    # jetanalyzer
+    @report_call, report_call, @test_call, test_call,
+    report_file, test_file, report_package, test_package, report_text, reportkey, test_text,
+    watch_file,
+    # optanalyzer
+    @report_opt, report_opt, @test_opt, test_opt,
+    # configurations
+    LastFrameModule, AnyFrameModule
+
 # Pre-release Julia versions are not supported, and we don't expect JET to even
 # precompile in pre-release versions. So, instead of having JET fail to precompile, we
 # simply make JET an empty module so that failure is delayed until the first time JET is
@@ -21,6 +34,7 @@ else
     If you want to load JET on a nightly version, set the `JET_DEV_MODE` Preferences.jl
     configuration to `true` and reload it.
     """
+    include("JETEmpty.jl")
 end
 
 end # module

src/JETBase.jl

@@ -1,16 +1,3 @@
-# exports
-# =======
-
-export
-    # jetanalyzer
-    @report_call, report_call, @test_call, test_call,
-    report_file, test_file, report_package, test_package, report_text, reportkey, test_text,
-    watch_file,
-    # optanalyzer
-    @report_opt, report_opt, @test_opt, test_opt,
-    # configurations
-    LastFrameModule, AnyFrameModule
-
 let README = normpath(dirname(@__DIR__), "README.md")
     s = read(README, String)
     s = replace(s,

src/JETEmpty.jl

@@ -0,0 +1,37 @@
+# Empty stubs for the exported functions/macros of JET.jl, to provide a more informative
+# error message when JET.jl is used with a pre-release version of Julia.
+
+const err_msg = strip("""
+    JET.jl does not guarantee compatibility with pre-release versions of Julia and
+    is not be loaded on this versions by default.
+        Julia VERSION = $VERSION
+    We recommend using a stable version of Julia in order to use JET.jl.
+    Or to try JET with this pre-release Julia version use Preferences.jl to enable
+    `JET_DEV_MODE`, and then reload JET. For example create a file named
+    `LocalPreferences.toml` which contains the line:
+        JET_DEV_MODE = true
+    Note that JET.jl may not function properly with a pre-release versions of Julia
+    even with `JET_DEV_MODE` enabled.
+    """)
+
+for exported_func in (
+    :report_call, :test_call,
+    :report_file, :test_file, :report_package, :test_package, :report_text, :reportkey, :test_text,
+    :watch_file,
+    # optanalyzer
+    :report_opt, :test_opt,
+    # configurations
+    :LastFrameModule, :AnyFrameModule
+)
+    @eval $exported_func(args...; kws...) = error($err_msg)
+end
+for exported_macro in (
+    :report_call, :test_call,
+    :report_opt, :test_opt
+)
+    @eval begin
+        macro $exported_macro(args...)
+            error($err_msg)
+        end
+    end
+end