clang-format.bash: Use Git attributes to mark files for formatting

.gitattributes

@@ -2,11 +2,11 @@
 .hooks*          export-ignore
 
 # Custom attribute to mark sources as using our C code style.
-[attr]our-c-style  whitespace=tab-in-indent
+[attr]our-c-style  whitespace=tab-in-indent  format.clang-format
 
 # Custom attribute to mark sources as generated.
-# Do not perform whitespace checks.
-[attr]generated  whitespace=-tab-in-indent,-indent-with-non-tab
+# Do not perform whitespace checks.  Do not format.
+[attr]generated  whitespace=-tab-in-indent,-indent-with-non-tab -format.clang-format
 
 bootstrap        crlf=input
 configure        crlf=input

Source/.gitattributes

@@ -15,3 +15,7 @@
 /cmFortranParser.cxx               generated
 /cmFortranParserTokens.h           generated
 /cmListFileLexer.c                 generated
+
+# Do not format third-party sources.
+/bindexplib.*                              -format.clang-format
+/kwsys/**                                  -format.clang-format

Source/CursesDialog/form/.gitattributes

+* -format.clang-format

Tests/CompileFeatures/.gitattributes

+# Do not format a source containing C++11 '>>' syntax as C++98.
+cxx_right_angle_brackets.cpp -format.clang-format

Tests/PositionIndependentTargets/.gitattributes

+# Do not format a source where we want a long line preserved.
+pic_test.h -format.clang-format

Tests/RunCMake/CommandLine/cmake_depends/.gitattributes

+# Do not format a source encoded in UTF-16.
+test_UTF-16LE.h -format.clang-format

Tests/RunCMake/GenerateExportHeader/reference/.gitattributes

+# Exclude reference content from formatting.
+* -format.clang-format

Utilities/.gitattributes

 /Git                    export-ignore
 /GitSetup               export-ignore
 SetupForDevelopment.sh  export-ignore
+
+# Do not format third-party sources.
+/KWIML/**       -format.clang-format
+/cm*/**         -format.clang-format

Utilities/Scripts/clang-format.bash

 #!/usr/bin/env bash
 #=============================================================================
-# Copyright 2015-2016 Kitware, Inc.
+# Copyright 2015-2017 Kitware, Inc.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -106,34 +106,12 @@ case "$mode" in
     *) die "invalid mode: $mode" ;;
 esac
 
-# Filter sources to which our style should apply.
-$git_ls -z -- '*.c' '*.cc' '*.cpp' '*.cxx' '*.h' '*.hh' '*.hpp' '*.hxx' '*.cu' '*.notcu' |
+# List files as selected above.
+$git_ls |
 
-  # Exclude lexer/parser generator input and output.
-  egrep -z -v '^Source/cmCommandArgumentLexer\.' |
-  egrep -z -v '^Source/cmCommandArgumentParser(\.y|\.cxx|Tokens\.h)' |
-  egrep -z -v '^Source/cmDependsJavaLexer\.' |
-  egrep -z -v '^Source/cmDependsJavaParser(\.y|\.cxx|Tokens\.h)' |
-  egrep -z -v '^Source/cmExprLexer\.' |
-  egrep -z -v '^Source/cmExprParser(\.y|\.cxx|Tokens\.h)' |
-  egrep -z -v '^Source/cmFortranLexer\.' |
-  egrep -z -v '^Source/cmFortranParser(\.y|\.cxx|Tokens\.h)' |
-  egrep -z -v '^Source/cmListFileLexer(\.in\.l|\.c)' |
-
-  # Exclude third-party sources.
-  egrep -z -v '^Source/bindexplib' |
-  egrep -z -v '^Source/(kwsys|CursesDialog/form)/' |
-  egrep -z -v '^Utilities/(KW|cm).*/' |
-
-  # Exclude reference content.
-  egrep -z -v '^Tests/RunCMake/GenerateExportHeader/reference/' |
-
-  # Exclude manually-formatted sources (e.g. with long lines).
-  egrep -z -v '^Tests/PositionIndependentTargets/pic_test.h' |
-  egrep -z -v '^Tests/CompileFeatures/cxx_right_angle_brackets.cpp' |
-
-  # Exclude sources with encoding not suported by clang-format.
-  egrep -z -v '^Tests/RunCMake/CommandLine/cmake_depends/test_UTF-16LE.h' |
+  # Select sources with our attribute.
+  git check-attr --stdin format.clang-format |
+  sed -n '/: format\.clang-format: set$/ {s/:[^:]*:[^:]*$//p}'  |
 
   # Update sources in-place.
-  xargs -0 "$clang_format" -i
+  xargs -d '\n' "$clang_format" -i