ClangFormat 13: add config and snippets (#108)

Add configuration file for ClangFormat 13 as well as C++ snippets
highlighting new features.

* prepare settings for future C++ 20 idioms like `requires` and `concepts`
* add new clang format 13 keys without changing the previous behavior

Additions compared to file clang-format-12:
* AlignArrayOfStructures: None
* BreakBeforeConceptDeclarations: true
* EmptyLineBeforeAccessModifier: Leave
* EmptyLineAfterAccessModifier: Leave
* IndentAccessModifiers: false
* IndentPPDirectives: None
* IndentRequires: false
* LambdaBodyIndentation: Signature
* PPIndentWidth: -1

Author: tristan0x

cpp/clang-format-13

@@ -0,0 +1,102 @@
+---
+AccessModifierOffset: -2
+AlignAfterOpenBracket: Align
+AlignArrayOfStructures: None
+AlignConsecutiveAssignments: false
+AlignConsecutiveDeclarations: false
+AlignConsecutiveMacros: true
+AlignEscapedNewlinesLeft: true
+AlignOperands: true
+AlignTrailingComments: true
+AllowAllParametersOfDeclarationOnNextLine: false
+AllowShortBlocksOnASingleLine: false
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: Empty
+AllowShortIfStatementsOnASingleLine: false
+AllowShortLoopsOnASingleLine: false
+AlwaysBreakBeforeMultilineStrings: true
+AlwaysBreakTemplateDeclarations: true
+BasedOnStyle: WebKit
+BinPackArguments: false
+BinPackParameters: false
+BraceWrapping:
+  AfterClass: false
+  AfterControlStatement: false
+  AfterEnum: false
+  AfterExternBlock: false
+  AfterFunction: false
+  AfterNamespace: false
+  AfterStruct: false
+  AfterUnion: false
+  BeforeCatch: false
+  BeforeElse: false
+BreakBeforeBraces: Custom
+BreakBeforeBinaryOperators: false
+BreakBeforeConceptDeclarations: true
+BreakBeforeTernaryOperators: true
+BreakConstructorInitializersBeforeComma: true
+BreakStringLiterals: true
+ColumnLimit: 100
+CommentPragmas:  '^ IWYU pragma:'
+ConstructorInitializerAllOnOneLineOrOnePerLine: false
+ConstructorInitializerIndentWidth: 4
+ContinuationIndentWidth: 4
+Cpp11BracedListStyle: true
+DerivePointerAlignment: false
+DerivePointerBinding: true
+EmptyLineBeforeAccessModifier: Leave
+EmptyLineAfterAccessModifier: Leave
+ExperimentalAutoDetectBinPacking: false
+FixNamespaceComments: true
+ForEachMacros:   [ foreach, Q_FOREACH, BOOST_FOREACH ]
+IncludeCategories:
+  - Regex:           '^"(llvm|llvm-c|clang|clang-c)/'
+    Priority:        2
+  - Regex:           '^(<|"(gtest|isl|json)/)'
+    Priority:        3
+  - Regex:           '.*'
+    Priority:        1
+IncludeIsMainRegex: '$'
+IndentAccessModifiers: false
+IndentCaseLabels: false
+IndentPPDirectives: None
+IndentRequires: false
+IndentWidth:     4
+IndentWrappedFunctionNames: false
+KeepEmptyLinesAtTheStartOfBlocks: false
+LambdaBodyIndentation: Signature
+Language: Cpp
+MaxEmptyLinesToKeep: 2
+NamespaceIndentation: None
+PenaltyBreakAssignment: 40
+PenaltyBreakBeforeFirstCallParameter: 100
+PenaltyBreakComment: 60
+PenaltyBreakFirstLessLess: 120
+PenaltyBreakString: 1000
+PenaltyExcessCharacter: 1000000
+PenaltyReturnTypeOnItsOwnLine: 200
+PointerAlignment: Left
+PointerBindsToType: true
+PPIndentWidth: -1
+ReflowComments:  true
+SortIncludes: true
+SpaceAfterCStyleCast: true
+SpaceAfterTemplateKeyword: true
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeCpp11BracedList: false
+SpaceBeforeCtorInitializerColon: false
+SpaceBeforeInheritanceColon: false
+SpaceBeforeParens: ControlStatements
+SpaceBeforeRangeBasedForLoopColon: false
+SpaceInEmptyBlock: false
+SpaceInEmptyParentheses: false
+SpacesBeforeTrailingComments: 2
+SpacesInAngles: false # '< ' style
+SpacesInContainerLiterals: false
+SpacesInCStyleCastParentheses: false
+SpacesInParentheses: false # '(' style
+SpacesInSquareBrackets: false
+Standard: c++14
+TabWidth: 4
+UseTab: Never
+...

cpp/formatting/README.md

@@ -46,6 +46,16 @@ thisIsAVeryLongMethodName(thisIsTheFirstArgument,
 ### Clang-Format configuration
 * `AlignAfterOpenBracket: Align`
 
+## Do not align fields in array initialization
+
+### Example
+```cpp
+struct test demo[] = {{56, 23, "hello"}, {-1, 93463, "world"}, {7, 5, "!!"}};
+
+```
+### Clang-Format configuration
+* `AlignArrayOfStructures: None`
+
 ## Do not align consecutive assignments
 
 ### Example
@@ -350,6 +360,19 @@ bool value =
 ### Clang-Format configuration
 * `BreakBeforeBinaryOperators: False`
 
+## New line before C++20 `concept` directive
+
+### Example
+```cpp
+template <typename T>
+concept Hashable = requires(T a) {
+    { std::hash<T>{}(a) } -> std::convertible_to<std::size_t>;
+};
+
+```
+### Clang-Format configuration
+* `BreakBeforeConceptDeclarations: True`
+
 ## break before long ternary operators
 
 ### Example
@@ -373,6 +396,28 @@ f(MyMap[{composite, key}]) new int[3]{1, 2, 3};
 ### Clang-Format configuration
 * `Cpp11BracedListStyle: True`
 
+## No line break restriction after access modifiers
+
+### Example
+```cpp
+struct foo {
+  private:
+    int i;
+
+  protected:
+    int j;
+    /* comment */
+  public:
+    foo() {}
+
+  private:
+  protected:
+};
+
+```
+### Clang-Format configuration
+* `EmptyLineBeforeAccessModifier: Leave`
+
 ## Recall namespace when closing it
 
 ### Example
@@ -383,6 +428,34 @@ foo();
 
 ```
 
+## Do no indent preprocesor directives
+
+### Example
+```cpp
+#if FOO
+#if BAR
+#include <foo>
+#endif  // BAR
+#endif  // FOO
+
+```
+### Clang-Format configuration
+* `IndentPPDirectives: None`
+
+## line break before C++20 `requires` directive
+
+### Example
+```cpp
+template <typename It>
+requires Iterator<It>
+void sort(It begin, It end) {
+    //....
+}
+
+```
+### Clang-Format configuration
+* `IndentRequires: False`
+
 ## Use 4 columns for indentation
 
 ### Example
@@ -398,6 +471,19 @@ void f() {
 ### Clang-Format configuration
 * `IndentWidth: 4`
 
+## Indent lambda body based on the signature of the lambda
+
+### Example
+```cpp
+callingSomeLongLongLongLongLongLongLongLongLongLongMethod(
+    [](SomeReallyLongLambdaSignatureArgument foo, SomeReallyLongLambdaSignatureArgument bar) {
+        return;
+    });
+
+```
+### Clang-Format configuration
+* `LambdaBodyIndentation: Signature`
+
 ## Do not indent when entering a *namespace*
 
 ### Example

cpp/formatting/snippets/AlignArrayOfStructures.cpp

@@ -0,0 +1,3 @@
+// Do not align fields in array initialization
+
+struct test demo[] = {{56, 23, "hello"}, {-1, 93463, "world"}, {7, 5, "!!"}};

cpp/formatting/snippets/BreakBeforeConceptDeclarations.cpp

@@ -0,0 +1,6 @@
+// New line before C++20 `concept` directive
+
+template <typename T>
+concept Hashable = requires(T a) {
+    { std::hash<T>{}(a) } -> std::convertible_to<std::size_t>;
+};

cpp/formatting/snippets/EmptyLineBeforeAccessModifier.cpp

@@ -0,0 +1,15 @@
+// No line break restriction after access modifiers
+
+struct foo {
+  private:
+    int i;
+
+  protected:
+    int j;
+    /* comment */
+  public:
+    foo() {}
+
+  private:
+  protected:
+};

cpp/formatting/snippets/IndentPPDirectives.cpp

@@ -0,0 +1,7 @@
+// Do no indent preprocesor directives
+
+#if FOO
+#if BAR
+#include <foo>
+#endif  // BAR
+#endif  // FOO

cpp/formatting/snippets/IndentRequires.cpp

@@ -0,0 +1,9 @@
+// line break before C++20 `requires` directive
+
+template <typename It>
+requires Iterator<It>
+    // clang-format off
+void sort(It begin, It end) {
+    //....
+}
+// clang-format on

cpp/formatting/snippets/LambdaBodyIndentation.cpp

@@ -0,0 +1,6 @@
+// Indent lambda body based on the signature of the lambda
+
+callingSomeLongLongLongLongLongLongLongLongLongLongMethod(
+    [](SomeReallyLongLambdaSignatureArgument foo, SomeReallyLongLambdaSignatureArgument bar) {
+        return;
+    });