Support autoinstall prompt

Author: LilithHafner

src/BasicAutoloads.jl

@@ -55,13 +55,27 @@ function (al::_Autoload)(@nospecialize(expr))
         target in al.already_ran && return expr
         push!(al.already_ran, target)
         try
+            try_autoinstall(target)
             Main.eval(target)
         catch err
             @info "Failed to run `$target`" exception=err
         end
     end
     expr
 end
+function try_autoinstall(expr::Expr)
+    REPL = Base.loaded_modules[Base.PkgId(Base.UUID("3fa0cd96-eef1-5676-8a61-b3b8758bbffb"), "REPL")]
+    isdefined(REPL, :install_packages_hooks) || return
+    expr.head in (:using, :import) || return
+    for arg in expr.args
+        arg isa Expr && arg.head == :. && length(arg.args) == 1 || continue
+        mod = only(arg.args)
+        mod isa Symbol && Base.identify_package(String(mod)) === nothing || continue
+        for f in REPL.install_packages_hooks
+            Base.invokelatest(f, [mod]) && break
+        end
+    end
+end
 
 function _register_ast_transform(ast_transform)
     if isdefined(Base, :active_repl_backend)