asdf: prepare for v0.16.0 release

asdf v0.16.0 is written in Go, and the build and install process for it has changed.

Formula/a/asdf.rb

@@ -1,8 +1,9 @@
 class Asdf < Formula
   desc "Extendable version manager with support for Ruby, Node.js, Erlang & more"
   homepage "https://asdf-vm.com/"
-  url "https://github.com/asdf-vm/asdf/archive/refs/tags/v0.15.0.tar.gz"
-  sha256 "d0cafe61d27b5e3fcb53658821bfbf744fd040a8ea28b0e22277e032b8e8f7fe"
+  url "https://github.com/asdf-vm/asdf.git", revision: "78a00fc90345bd77d83bb9b2b61f85756fceb1a6"
+  # , tag: "v0.16.0" # uncomment this when v0.16.0 is tagged
+  version "0.16.0-dev"
   license "MIT"
   head "https://github.com/asdf-vm/asdf.git", branch: "master"
 
@@ -16,38 +17,40 @@ class Asdf < Formula
     sha256 cellar: :any_skip_relocation, all: "a94dd362ce5c3a818f4fa56607eac3c616a3c1191e9f41480093bda2dc308af4"
   end
 
-  depends_on "autoconf"
-  depends_on "automake"
-  depends_on "coreutils"
-  depends_on "libtool"
-  depends_on "libyaml"
+  depends_on "go" => :build
+
   depends_on "openssl@3"
-  depends_on "readline"
-  depends_on "unixodbc"
 
   def install
-    bash_completion.install "completions/asdf.bash" => "asdf"
-    fish_completion.install "completions/asdf.fish"
-    zsh_completion.install "completions/_asdf"
-    libexec.install Dir["*"]
+    system("go", "build", *std_go_args(ldflags: "-s -X main.version=#{version}"), "./cmd/asdf")
+    original_stdout=$stdout
+
+    $stdout = File.new("asdf.bash", "w")
+    system(bin/"asdf", "completion", "bash")
+    bash_completion.install "asdf.bash" => "asdf"
+
+    $stdout = File.new("asdf.fish", "w")
+    system(bin/"asdf", "completion", "fish")
+    fish_completion.install "asdf.fish"
 
-    bin.write_exec_script libexec/"bin/asdf"
+    $stdout = File.new("_asdf", "w")
+    system(bin/"asdf", "completion", "zsh")
+    zsh_completion.install "_asdf"
+    $stdout = original_stdout
   end
 
   def caveats
     <<~EOS
-      To use asdf, add the following line (or equivalent) to your shell profile
-      e.g. ~/.profile or ~/.zshrc:
-        . #{opt_libexec}/asdf.sh
-      e.g. ~/.config/fish/config.fish
-        source #{opt_libexec}/asdf.fish
-      Restart your terminal for the settings to take effect.
+      To complete installation of asdf please follow the instructions on this page:
+
+      https://asdf-vm.com/guide/getting-started.html
+
+      Then restart your terminal for the settings to take effect.
     EOS
   end
 
   test do
     assert_match version.to_s, shell_output("#{bin}/asdf version")
-    output = shell_output("#{bin}/asdf plugin-list 2>&1")
-    assert_match "No plugins installed", output
+    assert_match "No plugins installed", shell_output("#{bin}/asdf plugin list 2>&1")
   end
 end