mkmf: fixed install directories of header files in extension libraries [Bug #17761]

When installing an extension library which provides a header, that
header should be installed under site_ruby (or vendor_ruby when
"--vendor" option was given to extconf.rb).  However, currently
this file is about to be installed in the core include directory.

1 files changed, 30 insertions, 0 deletions

diff --git a/test/mkmf/test_install.rb b/test/mkmf/test_install.rb
new file mode 100644
index 0000000000..7f8c603d42
--- /dev/null
+++ b/test/mkmf/test_install.rb
@@ -0,0 +1,30 @@
+# frozen_string_literal: false
+require_relative 'base'
+
+class TestMkmf
+  class TestInstall < TestMkmf
+    def test_install_dirs
+      Dir.mktmpdir do |dir|
+        File.write(dir+"/extconf.rb", "require 'mkmf'; create_makefile('test')")
+        all_assertions do |a|
+          a.foreach(
+            ["site"],
+            ["vendor", "--vendor"],
+          ) do |dest, *options|
+            assert_ruby_status(["-C", dir, "extconf.rb", *options])
+            mf = File.read(dir+"/Makefile")
+            a.foreach(
+              ["RUBYCOMMONDIR", "$(#{dest}dir)$(target_prefix)"],
+              ["RUBYLIBDIR",    "$(#{dest}libdir)$(target_prefix)"],
+              ["RUBYARCHDIR",   "$(#{dest}archdir)$(target_prefix)"],
+              ["HDRDIR",        "$(#{dest}hdrdir)$(target_prefix)"],
+              ["ARCHHDRDIR",    "$(#{dest}archhdrdir)$(target_prefix)"],
+            ) do |(var, path)|
+              assert_equal path, mf[/^#{var}\s*=\s*(.*)$/, 1]
+            end
+          end
+        end
+      end
+    end
+  end
+end