Title: Ruby 4.0 compatibility: try_constant raises TypeError in mkmf.rb

[NFZ441]

Environment

• Ruby: 4.0.3
• ruby-oci8: 2.2.14
• Oracle Instant Client: 19.23
• OS: Debian Trixie (Docker)

Problem

bundle install fails when compiling ruby-oci8 on Ruby 4.0.

Ruby 4.0 changed mkmf.rb's try_constant method — Integer(f.gets) at line 833 now raises TypeError when f.gets returns nil, instead of returning nil gracefully as in Ruby 3.x.

Error:
/usr/local/lib/ruby/4.0.0/mkmf.rb:833:in 'Kernel#Integer': can't convert nil into Integer (TypeError)

    return Integer(f.gets)
                   ^^^^^^

from /usr/local/lib/ruby/4.0.0/mkmf.rb:833:in 'block in MakeMakefile#try_constant'
from extconf.rb:34:in 'block in

'

Root Cause

In ext/oci8/extconf.rb line 33-34:

oci_major_version = checking_for 'OCI_MAJOR_VERSION in oci.h', fmt do
  try_constant('OCI_MAJOR_VERSION', 'oci.h')
end


try_constant compiles a small C program that prints the constant value. When the program produces no output, f.gets returns nil. In Ruby 3.x, Integer(nil) returned nil. In Ruby 4.0, it raises TypeError.

Suggested Fix:
Wrap try_constant calls in a rescue:

oci_major_version = checking_for 'OCI_MAJOR_VERSION in oci.h', fmt do
  begin; try_constant('OCI_MAJOR_VERSION', 'oci.h'); rescue TypeError; nil; end
end
if oci_major_version
  oci_minor_version = checking_for 'OCI_MINOR_VERSION in oci.h', fmt do
    begin; try_constant('OCI_MINOR_VERSION', 'oci.h'); rescue TypeError; nil; end
  end


ruby
This allows the existing fallback detection logic (have_func('OCILobGetLength2')) to work as intended.

Current Workaround
Patch mkmf.rb before bundle install:

sed -i 's/return Integer(f.gets)/return Integer(f.gets) rescue nil/' /usr/local/lib/ruby/4.0.0/mkmf.rb