[ruby/bigdecimal] Read version from bigdecimal.c

The dependency of extconf.h on bigdecimal.gemspec does not make sense
as far as no rule is defined for it.  Also, the relationship between
extension library and gemspec file is various in default gems, and
does not work well.

https://github.com/ruby/bigdecimal/commit/7f99b28552

1 files changed, 12 insertions, 2 deletions

diff --git a/ext/bigdecimal/bigdecimal.gemspec b/ext/bigdecimal/bigdecimal.gemspec
index a72205f517..f9f3b45616 100644
--- a/ext/bigdecimal/bigdecimal.gemspec
+++ b/ext/bigdecimal/bigdecimal.gemspec
@@ -1,8 +1,18 @@
 # coding: utf-8
 
+name = File.basename(__FILE__, '.*')
+source_version = ["", "ext/#{name}/"].find do |dir|
+  begin
+    break File.foreach(File.join(__dir__, "#{dir}#{name}.c")) {|line|
+      break $1.sub("-", ".") if /^#define\s+#{name.upcase}_VERSION\s+"(.+)"/o =~ line
+    }
+  rescue Errno::ENOENT
+  end
+end or raise "can't find #{name.upcase}_VERSION"
+
 Gem::Specification.new do |s|
-  s.name          = "bigdecimal"
-  s.version       = "3.1.3"
+  s.name          = name
+  s.version       = source_version
   s.authors       = ["Kenta Murata", "Zachary Scott", "Shigeo Kobayashi"]
   s.email         = ["[email protected]"]