Add compiler path to $PATH for subcommands

spec/primitives/external_command_spec.cr

@@ -4,31 +4,36 @@ require "../spec_helper"
 
 describe Crystal::Command do
   it "exec external commands", tags: %w[slow] do
-    with_temp_executable "crystal-external" do |path|
+    with_temp_executable "crystal-external" do |command_path|
+      compiler_path = File.expand_path(ENV["CRYSTAL_SPEC_COMPILER_BIN"]? || "bin/crystal")
+
       with_tempfile "crystal-external.cr" do |source_file|
         File.write source_file, <<-CRYSTAL
-          puts ENV["CRYSTAL"]?
+          puts Process.find_executable("crystal")
           puts PROGRAM_NAME
           puts ARGV
           CRYSTAL
 
-        Process.run(ENV["CRYSTAL_SPEC_COMPILER_BIN"]? || "bin/crystal", ["build", source_file, "-o", path])
+        Process.run(compiler_path, ["build", source_file, "-o", command_path])
       end
 
-      File.exists?(path).should be_true
+      File.exists?(command_path).should be_true
 
-      process = Process.new(ENV["CRYSTAL_SPEC_COMPILER_BIN"]? || "bin/crystal",
+      process = Process.new(compiler_path,
         ["external", "foo", "bar"],
         output: :pipe,
-        env: {"PATH" => {ENV["PATH"], File.dirname(path)}.join(Process::PATH_DELIMITER)}
+        env: {"PATH" => {ENV["PATH"], File.dirname(command_path)}.join(Process::PATH_DELIMITER)}
       )
-      output = process.output.gets_to_end
+      lines = process.output.gets_to_end.lines
+
       status = process.wait
       status.success?.should be_true
-      lines = output.lines
-      lines[0].should match /crystal/
-      lines[1].should match /crystal-external/
-      lines[2].should eq %(["foo", "bar"])
+
+      lines.should eq [
+        compiler_path,
+        command_path,
+        %(["foo", "bar"]),
+      ]
     end
   end
 end

src/compiler/crystal/command.cr

@@ -132,7 +132,12 @@ class Crystal::Command
         error "file '#{command}' does not exist"
       elsif external_command = Process.find_executable("crystal-#{command}")
         options.shift
-        Process.exec(external_command, options, env: {"CRYSTAL" => Process.executable_path})
+        if executable_path = Process.executable_path
+          crystal_path = File.dirname(executable_path)
+        end
+        path = [crystal_path, ENV["PATH"]?].compact_map!.join(Process::PATH_DELIMITER)
+
+        Process.exec(external_command, options, env: {"PATH" => path})
       else
         error "unknown command: #{command}"
       end