mkmf.rb: Refine message from `pkg_config`

lib/mkmf.rb

@@ -1849,66 +1849,73 @@ SRC
   # invoked with the options and a stripped output string is returned without
   # modifying any of the global values mentioned above.
   def pkg_config(pkg, *options)
-    _, ldir = dir_config(pkg)
-    if ldir
-      pkg_config_path = "#{ldir}/pkgconfig"
-      if File.directory?(pkg_config_path)
-        Logging.message("PKG_CONFIG_PATH = %s\n", pkg_config_path)
-        envs = ["PKG_CONFIG_PATH"=>[pkg_config_path, ENV["PKG_CONFIG_PATH"]].compact.join(File::PATH_SEPARATOR)]
-      end
+    fmt = "not found"
+    def fmt.%(x)
+      x ? x.inspect : self
     end
-    if pkgconfig = with_config("#{pkg}-config") and find_executable0(pkgconfig)
-      # if and only if package specific config command is given
-    elsif ($PKGCONFIG ||=
-           (pkgconfig = with_config("pkg-config") {config_string("PKG_CONFIG") || "pkg-config"}) &&
-           find_executable0(pkgconfig) && pkgconfig) and
-        xsystem([*envs, $PKGCONFIG, "--exists", pkg])
-      # default to pkg-config command
-      pkgconfig = $PKGCONFIG
-      args = [pkg]
-    elsif find_executable0(pkgconfig = "#{pkg}-config")
-      # default to package specific config command, as a last resort.
-    else
-      pkgconfig = nil
-    end
-    if pkgconfig
-      get = proc {|opts|
-        opts = Array(opts).map { |o| "--#{o}" }
-        opts = xpopen([*envs, pkgconfig, *opts, *args], err:[:child, :out], &:read)
-        Logging.open {puts opts.each_line.map{|s|"=> #{s.inspect}"}}
-        opts.strip if $?.success?
-      }
-    end
-    orig_ldflags = $LDFLAGS
-    if get and !options.empty?
-      get[options]
-    elsif get and try_ldflags(ldflags = get['libs'])
-      if incflags = get['cflags-only-I']
-        $INCFLAGS << " " << incflags
-        cflags = get['cflags-only-other']
-      else
-        cflags = get['cflags']
-      end
-      libs = get['libs-only-l']
-      if cflags
-        $CFLAGS += " " << cflags
-        $CXXFLAGS += " " << cflags
-      end
-      if libs
-        ldflags = (Shellwords.shellwords(ldflags) - Shellwords.shellwords(libs)).quote.join(" ")
-      else
-        libs, ldflags = Shellwords.shellwords(ldflags).partition {|s| s =~ /-l([^ ]+)/ }.map {|l|l.quote.join(" ")}
-      end
-      $libs += " " << libs
 
-      $LDFLAGS = [orig_ldflags, ldflags].join(' ')
-      Logging::message "package configuration for %s\n", pkg
-      Logging::message "incflags: %s\ncflags: %s\nldflags: %s\nlibs: %s\n\n",
-                       incflags, cflags, ldflags, libs
-      [[incflags, cflags].join(' '), ldflags, libs]
-    else
-      Logging::message "package configuration for %s is not found\n", pkg
-      nil
+    checking_for "pkg-config for #{pkg}", fmt do
+      _, ldir = dir_config(pkg)
+      if ldir
+        pkg_config_path = "#{ldir}/pkgconfig"
+        if File.directory?(pkg_config_path)
+          Logging.message("PKG_CONFIG_PATH = %s\n", pkg_config_path)
+          envs = ["PKG_CONFIG_PATH"=>[pkg_config_path, ENV["PKG_CONFIG_PATH"]].compact.join(File::PATH_SEPARATOR)]
+        end
+      end
+      if pkgconfig = with_config("#{pkg}-config") and find_executable0(pkgconfig)
+      # if and only if package specific config command is given
+      elsif ($PKGCONFIG ||=
+             (pkgconfig = with_config("pkg-config") {config_string("PKG_CONFIG") || "pkg-config"}) &&
+             find_executable0(pkgconfig) && pkgconfig) and
+           xsystem([*envs, $PKGCONFIG, "--exists", pkg])
+        # default to pkg-config command
+        pkgconfig = $PKGCONFIG
+        args = [pkg]
+      elsif find_executable0(pkgconfig = "#{pkg}-config")
+      # default to package specific config command, as a last resort.
+      else
+        pkgconfig = nil
+      end
+      if pkgconfig
+        get = proc {|opts|
+          opts = Array(opts).map { |o| "--#{o}" }
+          opts = xpopen([*envs, pkgconfig, *opts, *args], err:[:child, :out], &:read)
+          Logging.open {puts opts.each_line.map{|s|"=> #{s.inspect}"}}
+          opts.strip if $?.success?
+        }
+      end
+      orig_ldflags = $LDFLAGS
+      if get and !options.empty?
+        get[options]
+      elsif get and try_ldflags(ldflags = get['libs'])
+        if incflags = get['cflags-only-I']
+          $INCFLAGS << " " << incflags
+          cflags = get['cflags-only-other']
+        else
+          cflags = get['cflags']
+        end
+        libs = get['libs-only-l']
+        if cflags
+          $CFLAGS += " " << cflags
+          $CXXFLAGS += " " << cflags
+        end
+        if libs
+          ldflags = (Shellwords.shellwords(ldflags) - Shellwords.shellwords(libs)).quote.join(" ")
+        else
+          libs, ldflags = Shellwords.shellwords(ldflags).partition {|s| s =~ /-l([^ ]+)/ }.map {|l|l.quote.join(" ")}
+        end
+        $libs += " " << libs
+
+        $LDFLAGS = [orig_ldflags, ldflags].join(' ')
+        Logging::message "package configuration for %s\n", pkg
+        Logging::message "incflags: %s\ncflags: %s\nldflags: %s\nlibs: %s\n\n",
+                         incflags, cflags, ldflags, libs
+        [[incflags, cflags].join(' '), ldflags, libs]
+      else
+        Logging::message "package configuration for %s is not found\n", pkg
+        nil
+      end
     end
   end