[GR-16028] Use String#[] instead of Symbol#[] in Truffle::POSIX.

PullRequest: truffleruby/858

Author: eregon

CHANGELOG.md

@@ -13,6 +13,7 @@ Bug fixes:
 * Convert to intuitive Ruby exceptions when INVOKE fails (#1690).
 * Implemented `FFI::Pointer#clear` (#1687).
 * Procs will now yield to the block in their declaration context even when called with a block argument (#1657).
+* Fixed problems with calling POSIX methods if `Symbol#[]` is redefined (#1665).
 
 Compatibility
 

src/main/ruby/core/posix.rb

@@ -118,7 +118,7 @@ def self.attach_function_eagerly(native_name, argument_types, return_type,
 
       nfi_return_type = to_nfi_type(return_type)
       if nfi_return_type.to_s.start_with?('uint')
-        unsigned_return_type = 1 << nfi_return_type[-2..-1].to_i
+        unsigned_return_type = 1 << nfi_return_type.to_s[-2..-1].to_i
       end
 
       bound_func = func.bind("(#{nfi_args_types.join(',')}):#{nfi_return_type}")