From: "mame (Yusuke Endoh)" <mame@...>
Date: 2012-11-20T21:41:52+09:00
Subject: [ruby-core:49715] [ruby-trunk - Feature #4924] mkmf have_header fails with C++ headers


Issue #4924 has been updated by mame (Yusuke Endoh).

Target version set to next minor


----------------------------------------
Feature #4924: mkmf have_header fails with C++ headers
https://bugs.ruby-lang.org/issues/4924#change-33242

Author: adgar (Michael Edgar)
Status: Assigned
Priority: Low
Assignee: nobu (Nobuyoshi Nakada)
Category: 
Target version: next minor


=begin
When a user calls (({have_header('some_cpp_header.h')})), and then header includes a line such as(({ #include <string>})), mkmf will fail.

An example run follows:

+ extconf.rb

  require 'mkmf'
  have_library('stdc++')
  have_header('BasicBlock.h')
  create_makefile('laser/BasicBlock')

+ mkmf.log
  have_header: checking for BasicBlock.h... -------------------- no

  "gcc -E -I/Users/michaeledgar/.rvm/rubies/ruby-1.9.2-head/include/ruby-1.9.1/x86_64-darwin10.7.0 -I/Users/michaeledgar/.rvm/rubies/ruby-1.9.2-head/include/ruby-1.9.1/ruby/backward -I/Users/michaeledgar/.rvm/rubies/ruby-1.9.2-head/include/ruby-1.9.1 -I. -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE    -O3 -ggdb -Wextra -Wno-unused-parameter -Wno-parentheses -Wpointer-arith -Wwrite-strings -Wno-missing-field-initializers -Wshorten-64-to-32 -Wno-long-long  -fno-common -pipe  conftest.c -o conftest.i"
  In file included from conftest.c:3:
  ./BasicBlock.h:4:18: error: vector: No such file or directory
  ./BasicBlock.h:5:21: error: exception: No such file or directory
  ./BasicBlock.h:6:21: error: stdexcept: No such file or directory
  checked program was:
  /* begin */
  1: #include "ruby.h"
  2: 
  3: #include <BasicBlock.h>
  /* end */

The issue here is that the temporary file created to perform the header test is ((%conftest.c%)), not ((%conftest.cc%)) or ((%conftest.cpp%)). Changing the
name of the file and re-running gcc gives success.

In ((%mkmf.rb%)), have_header executes cpp_command, which creates the shell command to run. However, cpp_command uses the constant (({CONFTEST_C = "conftest.c"})). It should use a new constant, (({CONFTEST_CPP = "conftest.cc"})).

I've attached a patch that does this as expected. Tests pass; I'm unsure precisely how to construct
a test case that would be appropriate for the Ruby trunk. There are very few guiding examples in the
existing test suite.


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