[PATCH] Don't assume that llvm-config is a Perl script

0001-Don-t-assume-that-llvm-config-is-a-Perl-script.patch

As of the upcoming LLVM 3.1 release llvm-config has been rewritten as a
native executable [1]. Executing it with Perl causes the configure script
to fail with a message

    Unrecognized character \x7F; marked by <-- HERE after
    <-- HERE near column 1 at llvm-config line 1.

This commit makes llvm-config to be invoked directly. As a result it works
correctly with LLVM 3.0 and fails with a more friendly error message when
encountering LLVM 3.1svn.

[1] https://llvm.org/svn/llvm-project/llvm/branches/release_31/tools/llvm-config/?r=156062
---
 configure        |   23 +++++++++++++++++++----
 rakelib/build.rb |   19 ++++++-------------
 2 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/configure b/configure
index d4b7b75..f0be8ab 100755
--- a/configure
+++ b/configure
@@ -612,10 +612,10 @@ Unsupported language version requested: #{ver}. Options are #{@supported_version
   def setup_auto
     @log.print "  Checking for existing LLVM library tree: "
     if File.directory?("#{@llvm_default}/Release")
-      version = `#{@perl} #{@llvm_default}/Release/bin/llvm-config --version`.strip
+      version = `#{llvm_config_cmd "#{@llvm_default}/Release/bin/llvm-config"} --version`.strip
       if version == "3.0"
         # See if this has rtti turned off and reject it.
-        if `#{@perl} #{@llvm_default}/Release/bin/llvm-config --cxxflags`.index("-fno-rtti")
+        if `#{llvm_config_cmd "#{@llvm_default}/Release/bin/llvm-config"} --cxxflags`.index("-fno-rtti")
           @log.write "incorrectly configure (rtti is off)"
           remove_default
         else
@@ -667,10 +667,10 @@ Unsupported language version requested: #{ver}. Options are #{@supported_version
     end
 
     if config
-      version = `#{@perl} #{config} --version`.strip
+      version = `#{llvm_config_cmd config} --version`.strip
       parts = version.sub(/svn$/, "").split(".").map { |i| i.to_i }
       api_version = ("%d%02d" % parts[0..1]).to_i
-      if `#{@perl} #{config} --cxxflags`.index("-fno-rtti")
+      if `#{llvm_config_cmd config} --cxxflags`.index("-fno-rtti")
         @log.write "incorrectly configured llvm (rtti is off)"
       elsif api_version != 300
         @log.write "only LLVM 3.0 is supported"
@@ -1113,6 +1113,20 @@ int main() { return tgetnum(""); }
     @build_ruby
   end
 
+  # Checks whether the given config file is a Perl script by checking its first
+  # line for a Perl hashbang.
+  def llvm_config_cmd(config)
+    first_line = File.open(config).lines.first
+    if first_line =~ /^#! ?\/usr(\/local)?\/bin\/(env )?perl/
+      "#{@perl} #{config}"
+    else
+      config
+    end
+  rescue Errno::ENOENT, ArgumentError
+    # The file doesn't exist (ENOENT) or it's a binary file (ArgumentError).
+    config
+  end
+
   def get_system_name
     return unless @os =~ /linux/
     return unless File.exists? "/etc/issue"
@@ -1191,6 +1205,7 @@ module Rubinius
     :build_perl     => "#{@perl}",
     :llvm           => :#{@llvm},
     :llvm_configure => "#{@llvm_configure}",
+    :llvm_config_cmd => "#{llvm_config_cmd @llvm_configure}",
     :cc             => "#{@cc}",
     :cxx            => "#{@cxx}",
     :user_cflags    => "#{@user_cflags}",
diff --git a/rakelib/build.rb b/rakelib/build.rb
index 08d6172..ea8d66d 100644
--- a/rakelib/build.rb
+++ b/rakelib/build.rb
@@ -1,12 +1,5 @@
-def llvm_configure
-  case Rubinius::BUILD_CONFIG[:llvm]
-  when :svn, :prebuilt
-    "vendor/llvm/Release/bin/llvm-config"
-  when :config
-    Rubinius::BUILD_CONFIG[:llvm_configure]
-  else
-    raise "Tried to use LLVM unconfigure!"
-  end
+def llvm_config_cmd
+  Rubinius::BUILD_CONFIG[:llvm_config_cmd]
 end
 
 def build_perl
@@ -25,7 +18,7 @@ def llvm_flags
     @llvm_flags = []
   end
 
-  @llvm_flags += `#{build_perl} #{llvm_configure} --cflags`.split(/\s+/)
+  @llvm_flags += `#{llvm_config_cmd} --cflags`.split(/\s+/)
   @llvm_flags.delete_if { |e| e.index("-O") == 0 }
   @llvm_flags
 end
@@ -33,7 +26,7 @@ end
 def llvm_link_flags
   return "" unless LLVM_ENABLE
 
-  flags = `#{build_perl} #{llvm_configure} --ldflags`.strip
+  flags = `#{llvm_config_cmd} --ldflags`.strip
   flags.sub!(%r[-L/([a-zA-Z])/], '-L\1:/') if Rubinius::BUILD_CONFIG[:windows]
 
   flags
@@ -42,7 +35,7 @@ end
 def llvm_lib_files
   return [] unless LLVM_ENABLE
 
-  files = `#{build_perl} #{llvm_configure} --libfiles`.split(/\s+/)
+  files = `#{llvm_config_cmd} --libfiles`.split(/\s+/)
   files.select do |f|
     f.sub!(%r[^/([a-zA-Z])/], '\1:/') if Rubinius::BUILD_CONFIG[:windows]
     File.file? f
@@ -50,7 +43,7 @@ def llvm_lib_files
 end
 
 def llvm_version
-  `#{build_perl} #{llvm_configure} --version`.strip
+  `#{llvm_config_cmd} --version`.strip
 end
 
 def host_triple
-- 
1.7.10