fix: provide more helpful error messages

See rails#101 and comments in rails#96 for examples of what's confusing users.

Author: flavorjones

Diff for: .github/workflows/gem-install.yml

@@ -5,7 +5,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        platform: ["x64-mingw32", "x86_64-darwin", "x86_64-linux"]
+        platform: ["ruby", "x64-mingw32", "x86_64-darwin", "x86_64-linux"]
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
@@ -21,6 +21,20 @@ jobs:
           path: pkg
           retention-days: 1
 
+  vanilla-install:
+    needs: ["package"]
+    runs-on: ubuntu-latest
+    steps:
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: "3.0"
+      - uses: actions/download-artifact@v2
+        with:
+          name: gem-ruby
+          path: pkg
+      - run: "gem install pkg/tailwindcss-rails-*.gem"
+      - run: "tailwindcss 2>&1 | fgrep 'ERROR: Cannot find the tailwindcss executable'"
+
   linux-install:
     needs: ["package"]
     runs-on: ubuntu-latest

Diff for: exe/tailwindcss

@@ -2,17 +2,37 @@
 # because rubygems shims assume a gem's executables are Ruby
 
 require "shellwords"
+require "tailwindcss/upstream"
 
-platform_dir = Dir.glob(File.join(__dir__, "*")).select do |f|
-  File.directory?(f) && Gem::Platform.match(File.basename(f))
-end.first
-if platform_dir.nil?
-  raise "Cannot find the tailwindcss executable in #{__dir__} (1)"
+supported_platforms = Tailwindcss::Upstream::NATIVE_PLATFORMS.keys
+
+if supported_platforms.none? { |supported_platform| Gem::Platform.match(supported_platform) }
+  STDERR.puts(<<~ERRMSG)
+    ERROR: tailwindcss-rails does not support the #{::Gem::Platform.local} platform
+    Please install tailwindcss following instructions at https://tailwindcss.com/docs/installation
+  ERRMSG
+  exit 1
+end
+
+exe_path = Dir.glob(File.join(__dir__, "*", "tailwindcss")).find do |f|
+  Gem::Platform.match(File.basename(File.dirname(f)))
 end
+if exe_path.nil?
+  STDERR.puts(<<~ERRMSG)
+    ERROR: Cannot find the tailwindcss executable for #{::Gem::Platform.local} in #{__dir__}
+    If you're using bundler, please make sure you're on the latest bundler version:
+
+      gem install bundler
+      bundle update --bundler
+
+    Then make sure your lock file includes this platform by running:
+
+      bundle lock --add-platform #{::Gem::Platform.local}
+      bundle install
 
-exe_path = File.join(platform_dir, "tailwindcss")
-if !File.exist?(exe_path)
-  raise "Cannot find the tailwindcss executable in #{__dir__} (2)"
+    See `bundle lock --help` output for details.
+  ERRMSG
+  exit 1
 end
 
 command = Shellwords.join([exe_path, ARGV].flatten)

Diff for: rakelib/package.rake

@@ -77,7 +77,6 @@ Tailwindcss::Upstream::NATIVE_PLATFORMS.each do |platform, filename|
 
     # modify a copy of the gemspec to include the native executable
     gemspec.platform = platform
-    gemspec.executables << "tailwindcss"
     gemspec.files += [exepath, "LICENSE-DEPENDENCIES"]
 
     # create a package task

Diff for: tailwindcss-rails.gemspec

@@ -16,6 +16,7 @@ Gem::Specification.new do |spec|
 
   spec.files = Dir["{app,lib}/**/*", "MIT-LICENSE", "Rakefile", "README.md"]
   spec.bindir = "exe"
+  spec.executables << "tailwindcss"
 
   spec.add_dependency "railties", ">= 6.0.0"
 end