Make compiler aware of output extension when building programs

src/compiler/crystal/codegen/link.cr

@@ -104,14 +104,6 @@ module Crystal
   end
 
   class Program
-    def object_extension
-      case
-      when has_flag?("windows") then ".obj"
-      when has_flag?("wasm32")  then ".wasm"
-      else                           ".o"
-      end
-    end
-
     def lib_flags
       has_flag?("windows") ? lib_flags_windows : lib_flags_posix
     end

src/compiler/crystal/codegen/target.cr

@@ -77,6 +77,21 @@ class Crystal::Codegen::Target
     end
   end
 
+  def executable_extension
+    case
+    when windows? then ".exe"
+    else               ""
+    end
+  end
+
+  def object_extension
+    case
+    when windows?                  then ".obj"
+    when @architecture == "wasm32" then ".wasm"
+    else                                ".o"
+    end
+  end
+
   def macos?
     @environment.starts_with?("darwin") || @environment.starts_with?("macos")
   end

src/compiler/crystal/command.cr

@@ -327,14 +327,13 @@ class Crystal::Command
     compiler : Compiler,
     sources : Array(Compiler::Source),
     output_filename : String,
-    original_output_filename : String,
     arguments : Array(String),
     specified_output : Bool,
     hierarchy_exp : String?,
     cursor_location : String?,
     output_format : String? do
     def compile(output_filename = self.output_filename)
-      compiler.emit_base_filename = original_output_filename
+      compiler.emit_base_filename = output_filename.rchop(File.extname(output_filename))
       compiler.compile sources, output_filename
     end
 
@@ -521,17 +520,23 @@ class Crystal::Command
     if has_stdin_filename
       sources << Compiler::Source.new(filenames.shift, STDIN.gets_to_end)
     end
-    sources += gather_sources(filenames)
-    first_filename = sources.first.filename
-    first_file_ext = File.extname(first_filename)
-    original_output_filename = File.basename(first_filename, first_file_ext)
+    sources.concat gather_sources(filenames)
 
-    # Check if we'll overwrite the main source file
-    if first_file_ext.empty? && !output_filename && !no_codegen && !run && first_filename == File.expand_path(original_output_filename)
-      error "compilation will overwrite source file '#{Crystal.relative_filename(first_filename)}', either change its extension to '.cr' or specify an output file with '-o'"
+    output_extension = compiler.cross_compile? ? compiler.codegen_target.object_extension : compiler.codegen_target.executable_extension
+    if output_filename
+      if File.extname(output_filename).empty?
+        output_filename += output_extension
+      end
+    else
+      first_filename = sources.first.filename
+      output_filename = "#{::Path[first_filename].stem}#{output_extension}"
+
+      # Check if we'll overwrite the main source file
+      if !no_codegen && !run && first_filename == File.expand_path(output_filename)
+        error "compilation will overwrite source file '#{Crystal.relative_filename(first_filename)}', either change its extension to '.cr' or specify an output file with '-o'"
+      end
     end
 
-    output_filename ||= original_output_filename
     output_format ||= "text"
     unless output_format.in?("text", "json")
       error "You have input an invalid format, only text and JSON are supported"
@@ -543,7 +548,7 @@ class Crystal::Command
       error "can't use `#{output_filename}` as output filename because it's a directory"
     end
 
-    @config = CompilerConfig.new compiler, sources, output_filename, original_output_filename, arguments, specified_output, hierarchy_exp, cursor_location, output_format
+    @config = CompilerConfig.new compiler, sources, output_filename, arguments, specified_output, hierarchy_exp, cursor_location, output_format
   end
 
   private def gather_sources(filenames)

src/compiler/crystal/compiler.cr

@@ -39,7 +39,7 @@ module Crystal
     # If `true`, doesn't generate an executable but instead
     # creates a `.o` file and outputs a command line to link
     # it in the target machine.
-    property cross_compile = false
+    property? cross_compile = false
 
     # Compiler flags. These will be true when checked in macro
     # code by the `flag?(...)` macro method.
@@ -306,17 +306,16 @@ module Crystal
     private def cross_compile(program, units, output_filename)
       unit = units.first
       llvm_mod = unit.llvm_mod
-      object_name = output_filename + program.object_extension
 
       @progress_tracker.stage("Codegen (bc+obj)") do
         optimize llvm_mod if @release
 
         unit.emit(@emit_targets, emit_base_filename || output_filename)
 
-        target_machine.emit_obj_to_file llvm_mod, object_name
+        target_machine.emit_obj_to_file llvm_mod, output_filename
       end
 
-      _, command, args = linker_command(program, [object_name], output_filename, nil)
+      _, command, args = linker_command(program, [output_filename], output_filename, nil)
       print_command(command, args)
     end
 
@@ -693,7 +692,7 @@ module Crystal
           @name = "#{@name[0..16]}-#{::Crystal::Digest::MD5.hexdigest(@name)}"
         end
 
-        @object_extension = program.object_extension
+        @object_extension = compiler.codegen_target.object_extension
       end
 
       def compile

src/compiler/crystal/macros/macros.cr

@@ -127,7 +127,7 @@ class Crystal::Program
         # When cross-compiling, the host compiler shouldn't copy the config for
         # the target compiler and use the system defaults instead.
         # TODO: Add configuration overrides for host compiler to CLI.
-        unless compiler.cross_compile
+        unless compiler.cross_compile?
           host_compiler.flags = compiler.flags
           host_compiler.dump_ll = compiler.dump_ll?
           host_compiler.link_flags = compiler.link_flags