Merge pull request #6620 from tautschnig/cleanup/clang-format-includes

Codify grouping and order of includes

Author: tautschnig

.clang-format

@@ -47,7 +47,18 @@ NamespaceIndentation: None
 PenaltyBreakString: 10000
 PointerAlignment: Right
 ReflowComments: 'false'
-SortIncludes: 'true'
+IncludeBlocks: Regroup
+IncludeCategories:
+  - Regex: '<util/'
+    Priority: 1
+  - Regex: '<goto-programs/'
+    Priority: 2
+  - Regex: '<.+/.+>'
+    Priority: 3
+  - Regex: '^"[^/]+"$'
+    Priority: 4
+  - Regex: '<[^/]+>'
+    Priority: 5
 SpaceAfterCStyleCast: 'false'
 SpaceBeforeAssignmentOperators: 'true'
 SpaceBeforeParens: Never

CODING_STANDARD.md

@@ -148,7 +148,7 @@ Formatting is enforced using clang-format. For more information about this, see
 - The corresponding header for a given source file should always be the *first*
   include in the source file. For example, given `foo.h` and `foo.cpp`, the
   line `#include "foo.h"` should precede all other include statements in
-  `foo.cpp`.
+  `foo.cpp`. clang-format will enforce this.
 - Use the C++ versions of C headers (e.g. `cmath` instead of `math.h`).
   Some of the C headers use macros instead of functions which can have
   unexpected consequences.