Prefer /usr/bin/env xxx over /usr/bin/xxx where xxx = perl, python, awk

[haampie]

Summary

Allow users to use a non-system version of perl, python and awk, which is useful in certain package managers.

[haampie]

@JDevlieghere, would you care to review? This is another instance of moving away from system binaries to whatever the user / package manager wants the build to use.

[MaskRay]

#!/usr/bin/env perl -w (2 arguments) unfortunately does not work on Linux and many other systems.

[MaskRay]

Several llvm/utils/ scripts can probably just be removed.

[JDevlieghere]

In D95119#2525925, @MaskRay wrote:

#!/usr/bin/env perl -w (2 arguments) unfortunately does not work on Linux and many other systems.

Not sure if there's a similar thing for awk, but I think use warnings is preferred nowadays over perl -w.

[JDevlieghere]

Oops, didn't mean to accept.

[haampie]

I dropped the awk bits, since there's no portable way to do it there, and replaced all perl -w with perl and use warnings.

[JDevlieghere]

LGTM, unless @MaskRay has any other concerns.

[haampie]

Should this be merged?

[JDevlieghere]

In D95119#2584709, @haampie wrote:

Should this be merged?

Do you have commit access? If not I can land this for you.

[haampie]

I don't have commit access, would be great if you could do that for me!

clang/test/make_test_dirs.pl

-#!/usr/bin/perl -w
+#!/usr/bin/env perl
 #
 # Simple little Perl script that takes the cxx-sections.data file as
 # input and generates a directory structure that mimics the standard's
 # structure.
 use English;
+use warnings;
 
 $current_indent_level = -4;
 while ($line = <STDIN>) {
   $line =~ /^\s*/;
   $next_indent_level = length($MATCH);
   if ($line =~ /\[([^\]]*)\]/) {
     my $section = $1;
     while ($next_indent_level < $current_indent_level) {

clang/tools/scan-build/bin/set-xcode-analyzer

-#!/usr/bin/python
+#!/usr/bin/env python
 
 # [PR 11661] Note that we hardwire to /usr/bin/python because we
 # want to the use the system version of Python on Mac OS X.
 # This one has the scripting bridge enabled.
 
 import sys
 if sys.version_info < (3, 6):
     print "set-xcode-analyzer requires Python 3.6 or later"

clang/utils/TestUtils/pch-test.pl

-#!/usr/bin/perl -w
+#!/usr/bin/env perl
 
 # This tiny little script, which should be run from the clang
 # directory (with clang in your patch), tries to take each
 # compilable Clang test and build a PCH file from that test, then read
 # and dump the contents of the PCH file just created.
 use POSIX;
+use warnings;
 
 $exitcode = 0;
 sub testfiles($$) {
   my $suffix = shift;
   my $language = shift;
   my $passed = 0;
   my $failed = 0;
   my $skipped = 0;

clang/utils/analyzer/reducer.pl

-#!/usr/bin/perl -w
+#!/usr/bin/env perl
 use strict;
+use warnings;
 use File::Temp qw/ tempdir /;
 my $prog = "reducer";
 
 die "$prog <code file> <error string> [optional command]\n" if ($#ARGV < 0);
 my $file = shift @ARGV;
 die "$prog: [error] cannot read file $file\n" if (! -r $file);
 
 my $magic = shift @ARGV;

 else {
   my $compiler = "clang";
   $command = [$compiler, "-fsyntax-only", "-Wfatal-errors", "-Wno-deprecated-declarations", "-Wimplicit-function-declaration"];
 }
 push @$command, $srcFile;
 my $commandStr = "@$command";
 
 print OUT <<ENDTEXT;
-#!/usr/bin/perl -w
+#!/usr/bin/env perl
 use strict;
+use warnings;
 my \$BAD = 1;
 my \$GOOD = 0;
 `rm -f $reduceOut`;
 my \$command = "$commandStr > $reduceOut 2>&1";
 system(\$command);
 open(IN, "$reduceOut") or exit(\$BAD);
 my \$found = 0;
 while(<IN>) {

clang/utils/analyzer/update_plist_test.pl

-#!/usr/bin/perl -w
+#!/usr/bin/env perl
 use strict;
+use warnings;
 require File::Temp;
 use File::Temp ();
 
 die "update_plist_test <test file> <plist file>\n" if ($#ARGV < 1);
 my $testFile = shift @ARGV;
 die "error: cannot read file $testFile\n" if (! -r $testFile);
 my $plistFile = shift @ARGV;
 die "error: cannot read file $plistFile\n" if (! -r $plistFile);

clang/www/demo/index.cgi

-#!/usr/dcs/software/supported/bin/perl -w
+#!/usr/dcs/software/supported/bin/perl
 # LLVM Web Demo script
 #
 
 use strict;
 use CGI;
 use POSIX;
 use Mail::Send;
+use warnings;
 
 $| = 1;
 
 my $ROOT = "/tmp/webcompile";
 #my $ROOT = "/home/vadve/lattner/webcompile";
 
 open( STDERR, ">&STDOUT" ) or die "can't redirect stderr to stdout";
 

debuginfo-tests/llgdb-tests/test_debuginfo.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # This script tests debugging information generated by a compiler.
 # Input arguments
 #   - Input source program. Usually this source file is decorated using
 #     special comments to communicate debugger commands.
 #   - Executable file. This file is generated by the compiler.
 #
 # This perl script extracts debugger commands from input source program

lldb/docs/use/python-reference.rst

elif lldb.debugger:
       lldb.debugger.HandleCommand('command script add -f ls.ls ls')
       print 'The "ls" python command has been installed and is ready for use.'
 
 Now we can create a module called ls.py in the file ~/ls.py that will implement
 a function that can be used by LLDB's python command code:
 
 ::
 
-  #!/usr/bin/python
+  #!/usr/bin/env python
 
   import lldb
   import commands
   import optparse
   import shlex
 
   def ls(debugger, command, result, internal_dict):
       print >>result, (commands.getoutput('/bin/ls %s' % command))

 
 Now your python scripts are ready to import the lldb module. Below is a python
 script that will launch a program from the current working directory called
 "a.out", set a breakpoint at "main", and then run and hit the breakpoint, and
 print the process, thread and frame objects if the process stopped:
 
 ::
 
-  #!/usr/bin/python
+  #!/usr/bin/env python
 
   import lldb
   import os
 
   def disassemble_instructions(insts):
       for i in insts:
           print i
 

lldb/scripts/disasm-gdb-remote.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 use strict;
 
 #----------------------------------------------------------------------
 # Globals
 #----------------------------------------------------------------------
 our $unimplemented_str = "UNIMPLEMENTED";
 our $success_str = "OK";

llvm/utils/GenLibDeps.pl

-#!/usr/bin/perl -w
+#!/usr/bin/env perl
 #
 # Program:  GenLibDeps.pl
 #
 # Synopsis: Generate HTML output that shows the dependencies between a set of
 #           libraries. The output of this script should periodically replace 
 #           the similar content in the UsingLibraries.html document.
 #
 # Syntax:   GenLibDeps.pl [-flat] <directory_with_libraries_in_it> [path_to_nm_binary]

llvm/utils/codegen-diff

-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 use Getopt::Std;
 $DEBUG = 0;
 
 sub parse_objdump_file {
   my ($filename) = @_;
   my @result;
   open (INPUT, $filename) or die "$filename: $!\n";

llvm/utils/findsym.pl

-#!/usr/bin/perl -w
+#!/usr/bin/env perl
 #
 # Program:  findsym.pl
 #
 # Synopsis: Generate a list of the libraries in which a symbol is defined or
 #           referenced.
 #
 # Syntax:   findsym.pl <directory_with_libraries_in_it> <symbol>
 #
 
+use warnings;
+
 # Give first option a name.
 my $Directory = $ARGV[0];
 my $Symbol = $ARGV[1];
 
 # Open the directory and read its contents, sorting by name and differentiating
 # by whether its a library (.a) or an object file (.o)
 opendir DIR,$Directory;
 my @files = readdir DIR;

llvm/utils/llvm-compilers-check

-#!/usr/bin/python3
+#!/usr/bin/env python3
 ##===- utils/llvmbuild - Build the LLVM project ----------------*-python-*-===##
 #
 # Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 # See https://llvm.org/LICENSE.txt for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #
 ##===----------------------------------------------------------------------===##
 #

llvm/utils/llvm-native-gxx

-#!/usr/bin/perl
+#!/usr/bin/env perl
 # Wrapper around LLVM tools to generate a native .o from llvm-gxx using an
 # LLVM back-end (CBE by default).
 
 # set up defaults.
 $Verbose = 0;
 $SaveTemps = 1;
 $PreprocessOnly = 0;
 $CompileDontLink = 0;

openmp/runtime/tools/check-execstack.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 #
 #//===----------------------------------------------------------------------===//
 #//
 #// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 #// See https://llvm.org/LICENSE.txt for license information.
 #// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #//

openmp/runtime/tools/check-instruction-set.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 #
 #//===----------------------------------------------------------------------===//
 #//
 #// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 #// See https://llvm.org/LICENSE.txt for license information.
 #// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #//

openmp/runtime/tools/message-converter.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 #
 #//===----------------------------------------------------------------------===//
 #//
 #// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 #// See https://llvm.org/LICENSE.txt for license information.
 #// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #//

polly/lib/External/isl/doc/mypod2latex

-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 use strict;
 use Pod::LaTeX;
 
 my ($in, $out) = @ARGV;
 
 my $parser = new Pod::LaTeX(
     AddPreamble => 0,
     AddPostamble => 0,
     LevelNoNum => 5,
        );
 
 $parser->parse_from_file($in, $out);