[clang-format] Add new option to add spaces around conditions

Summary:
This diff adds a new option SpacesAroundConditions that inserts spaces inside the braces for conditional statements.

Reviewers: klimek, owenpan, mitchell-stellar, MyDeveloperDay

Patch by: timwoj

Subscribers: rsmmr, cfe-commits

Tags: clang, clang-format

Differential Revision: https://reviews.llvm.org/D68346

Author: Mitchell Balan

clang/docs/ClangFormatStyleOptions.rst

@@ -2328,6 +2328,9 @@ the configuration (without a prefix: ``Auto``).
      true:                                  false:
      x = ( int32 )y                 vs.     x = (int32)y
 
+**SpacesInConditionalStatement** (``bool``)
+  If ``true``, spaces will be inserted around if/for/while (and similar) conditions.
+
 **SpacesInContainerLiterals** (``bool``)
   If ``true``, spaces are inserted inside container literals (e.g.
   ObjC and Javascript array and dict literals).

clang/include/clang/Format/Format.h

@@ -1953,6 +1953,15 @@ struct FormatStyle {
   /// \endcode
   bool SpacesInAngles;
 
+  /// If ``true``, spaces will be inserted around if/for/switch/while
+  /// conditions.
+  /// \code
+  ///    true:                                  false:
+  ///    if ( a )  { ... }              vs.     if (a) { ... }
+  ///    while ( i < 5 )  { ... }               while (i < 5) { ... }
+  /// \endcode
+  bool SpacesInConditionalStatement;
+
   /// If ``true``, spaces are inserted inside container literals (e.g.
   /// ObjC and Javascript array and dict literals).
   /// \code{.js}
@@ -2155,6 +2164,7 @@ struct FormatStyle {
            SpaceInEmptyParentheses == R.SpaceInEmptyParentheses &&
            SpacesBeforeTrailingComments == R.SpacesBeforeTrailingComments &&
            SpacesInAngles == R.SpacesInAngles &&
+           SpacesInConditionalStatement == R.SpacesInConditionalStatement &&
            SpacesInContainerLiterals == R.SpacesInContainerLiterals &&
            SpacesInCStyleCastParentheses == R.SpacesInCStyleCastParentheses &&
            SpacesInParentheses == R.SpacesInParentheses &&

clang/lib/Format/Format.cpp

@@ -537,6 +537,8 @@ template <> struct MappingTraits<FormatStyle> {
     IO.mapOptional("SpacesBeforeTrailingComments",
                    Style.SpacesBeforeTrailingComments);
     IO.mapOptional("SpacesInAngles", Style.SpacesInAngles);
+    IO.mapOptional("SpacesInConditionalStatement",
+                   Style.SpacesInConditionalStatement);
     IO.mapOptional("SpacesInContainerLiterals",
                    Style.SpacesInContainerLiterals);
     IO.mapOptional("SpacesInCStyleCastParentheses",
@@ -817,6 +819,7 @@ FormatStyle getLLVMStyle(FormatStyle::LanguageKind Language) {
   LLVMStyle.SpaceBeforeCpp11BracedList = false;
   LLVMStyle.SpaceBeforeSquareBrackets = false;
   LLVMStyle.SpacesInAngles = false;
+  LLVMStyle.SpacesInConditionalStatement = false;
 
   LLVMStyle.PenaltyBreakAssignment = prec::Assignment;
   LLVMStyle.PenaltyBreakComment = 300;

clang/lib/Format/TokenAnnotator.cpp

@@ -2592,6 +2592,13 @@ bool TokenAnnotator::spaceRequiredBeforeParens(const FormatToken &Right) const {
           Right.ParameterCount > 0);
 }
 
+/// Returns \c true if the token is followed by a boolean condition, \c false
+/// otherwise.
+static bool isKeywordWithCondition(const FormatToken &Tok) {
+  return Tok.isOneOf(tok::kw_if, tok::kw_for, tok::kw_while, tok::kw_switch,
+                     tok::kw_constexpr);
+};
+
 bool TokenAnnotator::spaceRequiredBetween(const AnnotatedLine &Line,
                                           const FormatToken &Left,
                                           const FormatToken &Right) {
@@ -2610,6 +2617,15 @@ bool TokenAnnotator::spaceRequiredBetween(const AnnotatedLine &Line,
       (Left.is(tok::l_brace) && Left.BlockKind != BK_Block &&
        Right.is(tok::r_brace) && Right.BlockKind != BK_Block))
     return Style.SpaceInEmptyParentheses;
+  if (Style.SpacesInConditionalStatement) {
+    if (Left.is(tok::l_paren) && Left.Previous &&
+        isKeywordWithCondition(*Left.Previous))
+      return true;
+    if (Right.is(tok::r_paren) && Right.MatchingParen &&
+        Right.MatchingParen->Previous &&
+        isKeywordWithCondition(*Right.MatchingParen->Previous))
+      return true;
+  }
   if (Left.is(tok::l_paren) || Right.is(tok::r_paren))
     return (Right.is(TT_CastRParen) ||
             (Left.MatchingParen && Left.MatchingParen->is(TT_CastRParen)))
@@ -3044,7 +3060,8 @@ bool TokenAnnotator::spaceRequiredBefore(const AnnotatedLine &Line,
     // The identifier might actually be a macro name such as ALWAYS_INLINE. If
     // this turns out to be too lenient, add analysis of the identifier itself.
     return Right.WhitespaceRange.getBegin() != Right.WhitespaceRange.getEnd();
-  if (Right.is(tok::coloncolon) && !Left.isOneOf(tok::l_brace, tok::comment))
+  if (Right.is(tok::coloncolon) &&
+      !Left.isOneOf(tok::l_brace, tok::comment, tok::l_paren))
     return (Left.is(TT_TemplateOpener) &&
             Style.Standard < FormatStyle::LS_Cpp11) ||
            !(Left.isOneOf(tok::l_paren, tok::r_paren, tok::l_square,

clang/unittests/Format/FormatTest.cpp

@@ -12555,6 +12555,7 @@ TEST_F(FormatTest, ParsesConfigurationBools) {
   CHECK_PARSE_BOOL(SpacesInParentheses);
   CHECK_PARSE_BOOL(SpacesInSquareBrackets);
   CHECK_PARSE_BOOL(SpacesInAngles);
+  CHECK_PARSE_BOOL(SpacesInConditionalStatement);
   CHECK_PARSE_BOOL(SpaceInEmptyBlock);
   CHECK_PARSE_BOOL(SpaceInEmptyParentheses);
   CHECK_PARSE_BOOL(SpacesInContainerLiterals);
@@ -14880,6 +14881,22 @@ TEST_F(FormatTest, AmbersandInLamda) {
   verifyFormat("auto lambda = [&a = a]() { a = 2; };", AlignStyle);
 }
 
+ TEST_F(FormatTest, SpacesInConditionalStatement) {
+  FormatStyle Spaces = getLLVMStyle();
+  Spaces.SpacesInConditionalStatement = true;
+  verifyFormat("for ( int i = 0; i; i++ )\n  continue;", Spaces);
+  verifyFormat("if ( !a )\n  return;", Spaces);
+  verifyFormat("if ( a )\n  return;", Spaces);
+  verifyFormat("if constexpr ( a )\n  return;", Spaces);
+  verifyFormat("switch ( a )\ncase 1:\n  return;", Spaces);
+  verifyFormat("while ( a )\n  return;", Spaces);
+  verifyFormat("while ( (a && b) )\n  return;", Spaces);
+  verifyFormat("do {\n} while ( 1 != 0 );", Spaces);
+  // Check that space on the left of "::" is inserted as expected at beginning
+  // of condition.
+  verifyFormat("while ( ::func() )\n  return;", Spaces);
+}
+
 TEST_F(FormatTest, AlternativeOperators) {
   // Test case for ensuring alternate operators are not
   // combined with their right most neighbour.