[clang-format] [PR25010] AllowShortIfStatementsOnASingleLine not working if an "else" statement is present

[MyDeveloperDay]

Summary

Addressing: PR25010 - https://bugs.llvm.org/show_bug.cgi?id=25010

Code like:

if(true) var++;
else  {
    var--;
}

is reformatted to be

if (true)
  var++;
else {
  var--;
}

Even when AllowShortIfStatementsOnASingleLine is true

The following revision comes from a +1'd suggestion in the PR to support AllowShortIfElseStatementsOnASingleLine

This suppresses the clause prevents the merging of the if when there is a compound else

[MyDeveloperDay]

Add missing Format.h from the review

[Higuoxing]

clang/include/clang/Format/Format.h

247 ↗

(On Diff #189837)

Small nit:

AllowShortIfIfStatementsOnASingleLine
            ^

[MyDeveloperDay]

Fix spelling typo in documentation and comment

[reuk]

Does it make sense to allow AllowShortIfElseStatementsOnASingleLine to be enabled when AllowShortIfStatementsOnASingleLine is not?

Perhaps it would be better to have AllowShortIfStatementsOnASingleLine be represented by an enum with values Never, WithoutElse, Always. The old true/false values from config files prior to this change would need to be made to map to the appropriate enum keys.

[MyDeveloperDay]

In D59087#1423942, @reuk wrote:

Does it make sense to allow AllowShortIfElseStatementsOnASingleLine to be enabled when AllowShortIfStatementsOnASingleLine is not?

Perhaps it would be better to have AllowShortIfStatementsOnASingleLine be represented by an enum with values Never, WithoutElse, Always. The old true/false values from config files prior to this change would need to be made to map to the appropriate enum keys.

Thats a good point...its probably more code but I think it might be a better approach

[MyDeveloperDay]

Address review comments

• collapse two options into one

[reuk]

This looks much better now, thanks for taking another look! I've flagged some formatting/spelling nits, and I think the tests/docs could be a little more explicit about the behaviour of WithoutElse. Other than that, looks great!

clang/docs/ClangFormatStyleOptions.rst

375 ↗

(On Diff #190049)

For consistency, these descriptions should end with periods .

386 ↗

(On Diff #190049)

Missing .

390 ↗

(On Diff #190049)

I think an example of the generated formatting *with* a compound else statement would be useful here too, in addition to the existing example.

395 ↗

(On Diff #190049)

compounf -> compound

395 ↗

(On Diff #190049)

Missing .

clang/include/clang/Format/Format.h

264 ↗

(On Diff #190049)

Missing .

clang/lib/Format/UnwrappedLineFormatter.cpp

417 ↗

(On Diff #190049)

Has this line been clang-formatted? I'd expect spaces around the binop

clang/unittests/Format/FormatTest.cpp

494 ↗

(On Diff #190049)

I think having a test here which shows the expected behaviour for non-compound else statements with WithoutElse would be helpful, as in the documentation.

[MyDeveloperDay]

Address review comment

• add document and comment spelling and punctuation
• add additional unit tests to show non compound else clause case

[reuk]

The code looks good now. There's just a few places left where the formatting looks a bit suspect (sorry for missing those last time). I think once that's fixed this will be good to go.

clang/unittests/Format/FormatTest.cpp

553 ↗

(On Diff #190053)

This line, along with some of the following changed lines, have more than 80 characters. Make sure to clang-format changes! Consider using git-clang-format to format just this patch.

[MyDeveloperDay]

run git clang-format

[reuk]

LGTM

[krasimir]

I believe there is no such thing as an "short else statement". The else is part of the if statement and if it is present, I don't consider the whole if statement short. As such, IMO the bug is invalid.

[klimek]

cfe/trunk/docs/ClangFormatStyleOptions.rst

384

Is that actually the status quo or is the current behavior missing?

[MyDeveloperDay]

In D59087#1456129, @krasimir wrote:

I believe there is no such thing as an "short else statement". The else is part of the if statement and if it is present, I don't consider the whole if statement short. As such, IMO the bug is invalid.

I understand your point, but that is just one viewpoint only.

The opinion of the person who logged the defect (and I'm not that user just someone who wants to address the defects), whether something is a bug or not is 100% about their perspective, (that doesn't mean we have to address everything)

The question is does the change to the option hurt anyone who doesn't care? Is it useful the to the user requesting it? Does it significantly impact our ability to maintain the code, could it be useful to others.

cfe/trunk/docs/ClangFormatStyleOptions.rst

384

Yes that is "as was"

[klimek]

cfe/trunk/docs/ClangFormatStyleOptions.rst

384

Ok, that seems... wrong :)
Specifically, I'd at least expect the first one to also do

if (a) return;
else return;

That would be SIS_Always now? If so, could we make "true" just be "Always"?

cfe/trunk/docs/ClangFormatStyleOptions.rst

* ``SFS_All`` (in configuration: ``All``)
 
     .. code-block:: c++
 
       class Foo {
         void f() { foo(); }
       };
       void f() { bar(); }
 
+**AllowShortIfStatementsOnASingleLine** (``ShortIfStyle``)
+  Dependent on the value, ``if (a) return 0;`` can be put on a
+  single line.
+
+  Possible values:
+
+  * ``SIS_Never`` (in configuration: ``Never``)
+    Do not allow short if functions.
+
+    .. code-block:: c++
+
+       if (a)
+         return;
+       else
+         return;
+
+  * ``SIS_WithoutElse`` (in configuration: ``WithoutElse``)
+    Allow short if functions on the same line, as long as else
+    is not a compound statement.
+
+    .. code-block:: c++
 
+       if (a) return;
+       else
+         return;
+
+       if (a)
+         return;
+       else {
+         return;
+       }
 
-**AllowShortIfStatementsOnASingleLine** (``bool``)
-  If ``true``, ``if (a) return;`` can be put on a single line.
+  * ``SIS_Always`` (in configuration: ``Always``)
+    Allow short if statements even if the else is a compound statement.
+
+    .. code-block:: c++
+
+       if (a) return;
+       else {
+          return;
+       }
 
 **AllowShortLoopsOnASingleLine** (``bool``)
   If ``true``, ``while (true) continue;`` can be put on a single
   line.
 
 **AlwaysBreakAfterDefinitionReturnType** (``DefinitionReturnTypeBreakingStyle``)
   The function definition return type breaking style to use.  This
   option is **deprecated** and is retained for backwards compatibility.

cfe/trunk/include/clang/Format/Format.h

enum ShortFunctionStyle {
     /// \endcode
     SFS_All,
   };
 
   /// Dependent on the value, ``int f() { return 0; }`` can be put on a
   /// single line.
   ShortFunctionStyle AllowShortFunctionsOnASingleLine;
 
+  /// Different styles for handling short if lines
+  enum ShortIfStyle {
+    /// Never put short ifs on the same line.
+    /// \code
+    ///   if (a)
+    ///     return ;
+    ///   else {
+    ///     return;
+    ///   }
+    /// \endcode
+    SIS_Never,
+    /// Without else put short ifs on the same line only if
+    /// the else is not a compound statement.
+    /// \code
+    ///   if (a) return;
+    ///   else
+    ///     return;
+    /// \endcode
+    SIS_WithoutElse,
+    /// Always put short ifs on the same line if
+    /// the else is not a compound statement or not.
+    /// \code
+    ///   if (a) return;
+    ///   else {
+    ///     return;
+    ///   }
+    /// \endcode
+    SIS_Always,
+  };
+
   /// If ``true``, ``if (a) return;`` can be put on a single line.
-  bool AllowShortIfStatementsOnASingleLine;
+  ShortIfStyle AllowShortIfStatementsOnASingleLine;
 
   /// If ``true``, ``while (true) continue;`` can be put on a single
   /// line.
   bool AllowShortLoopsOnASingleLine;
 
   /// Different ways to break after the function definition return type.
   /// This option is **deprecated** and is retained for backwards compatibility.
   enum DefinitionReturnTypeBreakingStyle {

cfe/trunk/lib/Format/Format.cpp

static void enumeration(IO &IO, FormatStyle::ShortFunctionStyle &Value) {
     IO.enumCase(Value, "All", FormatStyle::SFS_All);
     IO.enumCase(Value, "true", FormatStyle::SFS_All);
     IO.enumCase(Value, "Inline", FormatStyle::SFS_Inline);
     IO.enumCase(Value, "InlineOnly", FormatStyle::SFS_InlineOnly);
     IO.enumCase(Value, "Empty", FormatStyle::SFS_Empty);
   }
 };
 
+template <> struct ScalarEnumerationTraits<FormatStyle::ShortIfStyle> {
+  static void enumeration(IO &IO, FormatStyle::ShortIfStyle &Value) {
+    IO.enumCase(Value, "Never", FormatStyle::SIS_Never);
+    IO.enumCase(Value, "Always", FormatStyle::SIS_Always);
+    IO.enumCase(Value, "WithoutElse", FormatStyle::SIS_WithoutElse);
+
+    // For backward compatibility.
+    IO.enumCase(Value, "false", FormatStyle::SIS_Never);
+    IO.enumCase(Value, "true", FormatStyle::SIS_WithoutElse);
+  }
+};
+
 template <> struct ScalarEnumerationTraits<FormatStyle::BinPackStyle> {
   static void enumeration(IO &IO, FormatStyle::BinPackStyle &Value) {
     IO.enumCase(Value, "Auto", FormatStyle::BPS_Auto);
     IO.enumCase(Value, "Always", FormatStyle::BPS_Always);
     IO.enumCase(Value, "Never", FormatStyle::BPS_Never);
   }
 };
 
FormatStyle getLLVMStyle(FormatStyle::LanguageKind Language) {
   LLVMStyle.AlignOperands = true;
   LLVMStyle.AlignTrailingComments = true;
   LLVMStyle.AlignConsecutiveAssignments = false;
   LLVMStyle.AlignConsecutiveDeclarations = false;
   LLVMStyle.AllowAllParametersOfDeclarationOnNextLine = true;
   LLVMStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_All;
   LLVMStyle.AllowShortBlocksOnASingleLine = false;
   LLVMStyle.AllowShortCaseLabelsOnASingleLine = false;
-  LLVMStyle.AllowShortIfStatementsOnASingleLine = false;
+  LLVMStyle.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_Never;
   LLVMStyle.AllowShortLoopsOnASingleLine = false;
   LLVMStyle.AlwaysBreakAfterReturnType = FormatStyle::RTBS_None;
   LLVMStyle.AlwaysBreakAfterDefinitionReturnType = FormatStyle::DRTBS_None;
   LLVMStyle.AlwaysBreakBeforeMultilineStrings = false;
   LLVMStyle.AlwaysBreakTemplateDeclarations = FormatStyle::BTDS_MultiLine;
   LLVMStyle.BinPackArguments = true;
   LLVMStyle.BinPackParameters = true;
   LLVMStyle.BreakBeforeBinaryOperators = FormatStyle::BOS_None;
if (Language == FormatStyle::LK_TextProto) {
 
     return GoogleStyle;
   }
 
   FormatStyle GoogleStyle = getLLVMStyle(Language);
 
   GoogleStyle.AccessModifierOffset = -1;
   GoogleStyle.AlignEscapedNewlines = FormatStyle::ENAS_Left;
-  GoogleStyle.AllowShortIfStatementsOnASingleLine = true;
+  GoogleStyle.AllowShortIfStatementsOnASingleLine =
+      FormatStyle::SIS_WithoutElse;
   GoogleStyle.AllowShortLoopsOnASingleLine = true;
   GoogleStyle.AlwaysBreakBeforeMultilineStrings = true;
   GoogleStyle.AlwaysBreakTemplateDeclarations = FormatStyle::BTDS_Yes;
   GoogleStyle.ConstructorInitializerAllOnOneLineOrOnePerLine = true;
   GoogleStyle.DerivePointerAlignment = true;
   GoogleStyle.IncludeStyle.IncludeCategories = {
       {"^<ext/.*\\.h>", 2}, {"^<.*\\.h>", 1}, {"^<.*", 2}, {".*", 3}};
   GoogleStyle.IncludeStyle.IncludeIsMainRegex = "([-_](test|unittest))?$";
FormatStyle getGoogleStyle(FormatStyle::LanguageKind Language) {
   GoogleStyle.PenaltyReturnTypeOnItsOwnLine = 200;
   GoogleStyle.PenaltyBreakBeforeFirstCallParameter = 1;
 
   if (Language == FormatStyle::LK_Java) {
     GoogleStyle.AlignAfterOpenBracket = FormatStyle::BAS_DontAlign;
     GoogleStyle.AlignOperands = false;
     GoogleStyle.AlignTrailingComments = false;
     GoogleStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_Empty;
-    GoogleStyle.AllowShortIfStatementsOnASingleLine = false;
+    GoogleStyle.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_Never;
     GoogleStyle.AlwaysBreakBeforeMultilineStrings = false;
     GoogleStyle.BreakBeforeBinaryOperators = FormatStyle::BOS_NonAssignment;
     GoogleStyle.ColumnLimit = 100;
     GoogleStyle.SpaceAfterCStyleCast = true;
     GoogleStyle.SpacesBeforeTrailingComments = 1;
   } else if (Language == FormatStyle::LK_JavaScript) {
     GoogleStyle.AlignAfterOpenBracket = FormatStyle::BAS_AlwaysBreak;
     GoogleStyle.AlignOperands = false;
FormatStyle getGoogleStyle(FormatStyle::LanguageKind Language) {
   }
 
   return GoogleStyle;
 }
 
 FormatStyle getChromiumStyle(FormatStyle::LanguageKind Language) {
   FormatStyle ChromiumStyle = getGoogleStyle(Language);
   if (Language == FormatStyle::LK_Java) {
-    ChromiumStyle.AllowShortIfStatementsOnASingleLine = true;
+    ChromiumStyle.AllowShortIfStatementsOnASingleLine =
+        FormatStyle::SIS_WithoutElse;
     ChromiumStyle.BreakAfterJavaFieldAnnotations = true;
     ChromiumStyle.ContinuationIndentWidth = 8;
     ChromiumStyle.IndentWidth = 4;
     // See styleguide for import groups:
     // https://chromium.googlesource.com/chromium/src/+/master/styleguide/java/java.md#Import-Order
     ChromiumStyle.JavaImportGroups = {
         "android",      "com",  "dalvik",
         "junit",        "org",  "com.google.android.apps.chrome",
         "org.chromium", "java", "javax",
     };
     ChromiumStyle.SortIncludes = true;
   } else if (Language == FormatStyle::LK_JavaScript) {
-    ChromiumStyle.AllowShortIfStatementsOnASingleLine = false;
+    ChromiumStyle.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_Never;
     ChromiumStyle.AllowShortLoopsOnASingleLine = false;
   } else {
     ChromiumStyle.AllowAllParametersOfDeclarationOnNextLine = false;
     ChromiumStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_Inline;
-    ChromiumStyle.AllowShortIfStatementsOnASingleLine = false;
+    ChromiumStyle.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_Never;
     ChromiumStyle.AllowShortLoopsOnASingleLine = false;
     ChromiumStyle.BinPackParameters = false;
     ChromiumStyle.DerivePointerAlignment = false;
     if (Language == FormatStyle::LK_ObjC)
       ChromiumStyle.ColumnLimit = 80;
   }
   return ChromiumStyle;
 }

cfe/trunk/lib/Format/UnwrappedLineFormatter.cpp

unsigned tryMergeSimpleControlStatement(
     AnnotatedLine &Line = **I;
     if (Line.Last->isNot(tok::r_paren))
       return 0;
     if (1 + I[1]->Last->TotalLength > Limit)
       return 0;
     if (I[1]->First->isOneOf(tok::semi, tok::kw_if, tok::kw_for, tok::kw_while,
                              TT_LineComment))
       return 0;
-    // Only inline simple if's (no nested if or else).
+    // Only inline simple if's (no nested if or else), unless specified
+    if (Style.AllowShortIfStatementsOnASingleLine != FormatStyle::SIS_Always) {
       if (I + 2 != E && Line.startsWith(tok::kw_if) &&
           I[2]->First->is(tok::kw_else))
         return 0;
+    }
     return 1;
   }
 
   unsigned
   tryMergeShortCaseLabels(SmallVectorImpl<AnnotatedLine *>::const_iterator I,
                           SmallVectorImpl<AnnotatedLine *>::const_iterator E,
                           unsigned Limit) {
     if (Limit == 0 || I + 1 == E ||

cfe/trunk/unittests/Format/FormatTest.cpp

TEST_F(FormatTest, FormatIfWithoutCompoundStatement) {
   verifyFormat("if constexpr (a)\n"
                "  if constexpr (b) {\n"
                "    f();\n"
                "  }\n"
                "g();");
 
   FormatStyle AllowsMergedIf = getLLVMStyle();
   AllowsMergedIf.AlignEscapedNewlines = FormatStyle::ENAS_Left;
-  AllowsMergedIf.AllowShortIfStatementsOnASingleLine = true;
+  AllowsMergedIf.AllowShortIfStatementsOnASingleLine =
+      FormatStyle::SIS_WithoutElse;
   verifyFormat("if (a)\n"
                "  // comment\n"
                "  f();",
                AllowsMergedIf);
   verifyFormat("{\n"
                "  if (a)\n"
                "  label:\n"
                "    f();\n"
TEST_F(FormatTest, FormatIfWithoutCompoundStatement) {
   verifyFormat("if (aaaaaaaaa)\n"
                "  return;",
                AllowsMergedIf);
 
   AllowsMergedIf.ColumnLimit = 13;
   verifyFormat("if (a)\n  return;", AllowsMergedIf);
 }
 
+TEST_F(FormatTest, FormatIfWithoutCompoundStatementButElseWith) {
+  FormatStyle AllowsMergedIf = getLLVMStyle();
+  AllowsMergedIf.AlignEscapedNewlines = FormatStyle::ENAS_Left;
+  AllowsMergedIf.AllowShortIfStatementsOnASingleLine =
+      FormatStyle::SIS_WithoutElse;
+  verifyFormat("if (a)\n"
+               "  f();\n"
+               "else {\n"
+               "  g();\n"
+               "}",
+               AllowsMergedIf);
+  verifyFormat("if (a)\n"
+               "  f();\n"
+               "else\n"
+               "  g();\n",
+               AllowsMergedIf);
+
+  AllowsMergedIf.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_Always;
+
+  verifyFormat("if (a) f();\n"
+               "else {\n"
+               "  g();\n"
+               "}",
+               AllowsMergedIf);
+  verifyFormat("if (a) f();\n"
+               "else {\n"
+               "  if (a) f();\n"
+               "  else {\n"
+               "    g();\n"
+               "  }\n"
+               "  g();\n"
+               "}",
+               AllowsMergedIf);
+}
+
 TEST_F(FormatTest, FormatLoopsWithoutCompoundStatement) {
   FormatStyle AllowsMergedLoops = getLLVMStyle();
   AllowsMergedLoops.AllowShortLoopsOnASingleLine = true;
   verifyFormat("while (true) continue;", AllowsMergedLoops);
   verifyFormat("for (;;) continue;", AllowsMergedLoops);
   verifyFormat("for (int &v : vec) v *= 2;", AllowsMergedLoops);
   verifyFormat("while (true)\n"
                "  ;",
verifyFormat("for (;;) /* still don't merge */\n"
                AllowsMergedLoops);
 }
 
 TEST_F(FormatTest, FormatShortBracedStatements) {
   FormatStyle AllowSimpleBracedStatements = getLLVMStyle();
   AllowSimpleBracedStatements.ColumnLimit = 40;
   AllowSimpleBracedStatements.AllowShortBlocksOnASingleLine = true;
 
-  AllowSimpleBracedStatements.AllowShortIfStatementsOnASingleLine = true;
+  AllowSimpleBracedStatements.AllowShortIfStatementsOnASingleLine =
+      FormatStyle::SIS_WithoutElse;
   AllowSimpleBracedStatements.AllowShortLoopsOnASingleLine = true;
 
   AllowSimpleBracedStatements.BreakBeforeBraces = FormatStyle::BS_Custom;
   AllowSimpleBracedStatements.BraceWrapping.AfterFunction = true;
   AllowSimpleBracedStatements.BraceWrapping.SplitEmptyRecord = false;
 
   verifyFormat("if (true) {}", AllowSimpleBracedStatements);
   verifyFormat("if constexpr (true) {}", AllowSimpleBracedStatements);
verifyFormat("typedef struct A2 {\n"
                "  int X;\n"
                "} A2_t;",
                AllowSimpleBracedStatements);
   verifyFormat("template <int> struct A2 {\n"
                "  struct B {};\n"
                "};",
                AllowSimpleBracedStatements);
 
-  AllowSimpleBracedStatements.AllowShortIfStatementsOnASingleLine = false;
+  AllowSimpleBracedStatements.AllowShortIfStatementsOnASingleLine =
+      FormatStyle::SIS_Never;
   verifyFormat("if (true) {}", AllowSimpleBracedStatements);
   verifyFormat("if (true) {\n"
                "  f();\n"
                "}",
                AllowSimpleBracedStatements);
   verifyFormat("if (true) {\n"
                "  f();\n"
                "} else {\n"
                "  f();\n"
                "}",
                AllowSimpleBracedStatements);
 
   AllowSimpleBracedStatements.AllowShortLoopsOnASingleLine = false;
   verifyFormat("while (true) {}", AllowSimpleBracedStatements);
   verifyFormat("while (true) {\n"
                "  f();\n"
                "}",
                AllowSimpleBracedStatements);
   verifyFormat("for (;;) {}", AllowSimpleBracedStatements);
   verifyFormat("for (;;) {\n"
                "  f();\n"
                "}",
                AllowSimpleBracedStatements);
 
-  AllowSimpleBracedStatements.AllowShortIfStatementsOnASingleLine = true;
+  AllowSimpleBracedStatements.AllowShortIfStatementsOnASingleLine =
+      FormatStyle::SIS_WithoutElse;
   AllowSimpleBracedStatements.AllowShortLoopsOnASingleLine = true;
   AllowSimpleBracedStatements.BraceWrapping.AfterControlStatement = true;
 
   verifyFormat("if (true) {}", AllowSimpleBracedStatements);
   verifyFormat("if constexpr (true) {}", AllowSimpleBracedStatements);
   verifyFormat("while (true) {}", AllowSimpleBracedStatements);
   verifyFormat("for (;;) {}", AllowSimpleBracedStatements);
   verifyFormat("if (true) { f(); }", AllowSimpleBracedStatements);
verifyFormat("if (true)\n"
                "{\n"
                "  f();\n"
                "} else\n"
                "{\n"
                "  f();\n"
                "}",
                AllowSimpleBracedStatements);
 
-  AllowSimpleBracedStatements.AllowShortIfStatementsOnASingleLine = false;
+  AllowSimpleBracedStatements.AllowShortIfStatementsOnASingleLine =
+      FormatStyle::SIS_Never;
   verifyFormat("if (true) {}", AllowSimpleBracedStatements);
   verifyFormat("if (true)\n"
                "{\n"
                "  f();\n"
                "}",
                AllowSimpleBracedStatements);
   verifyFormat("if (true)\n"
                "{\n"
verifyFormat("for (;;)\n"
                "  f();\n"
                "}",
                AllowSimpleBracedStatements);
 }
 
 TEST_F(FormatTest, ShortBlocksInMacrosDontMergeWithCodeAfterMacro) {
   FormatStyle Style = getLLVMStyleWithColumns(60);
   Style.AllowShortBlocksOnASingleLine = true;
-  Style.AllowShortIfStatementsOnASingleLine = true;
+  Style.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_WithoutElse;
   Style.BreakBeforeBraces = FormatStyle::BS_Allman;
   EXPECT_EQ("#define A                                                  \\\n"
             "  if (HANDLEwernufrnuLwrmviferuvnierv)                     \\\n"
             "  { RET_ERR1_ANUIREUINERUIFNIOAerwfwrvnuier; }\n"
             "X;",
             format("#define A \\\n"
                    "   if (HANDLEwernufrnuLwrmviferuvnierv) { \\\n"
                    "      RET_ERR1_ANUIREUINERUIFNIOAerwfwrvnuier; \\\n"

 
 TEST_F(FormatTest, GraciouslyHandleIncorrectPreprocessorConditions) {
   verifyFormat("#endif\n"
                "#if B");
 }
 
 TEST_F(FormatTest, FormatsJoinedLinesOnSubsequentRuns) {
   FormatStyle SingleLine = getLLVMStyle();
-  SingleLine.AllowShortIfStatementsOnASingleLine = true;
+  SingleLine.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_WithoutElse;
   verifyFormat("#if 0\n"
                "#elif 1\n"
                "#endif\n"
                "void foo() {\n"
                "  if (test) foo2();\n"
                "}",
                SingleLine);
 }
verifyFormat(
       "#elif !defined(AAAAAA) && (defined CCCCC || defined DDDDDD) &&  \\\n"
       "    defined(BBBBBBBB)\n"
       "#endif",
       getLLVMStyleWithColumns(65));
 }
 
 TEST_F(FormatTest, MergeHandlingInTheFaceOfPreprocessorDirectives) {
   FormatStyle AllowsMergedIf = getGoogleStyle();
-  AllowsMergedIf.AllowShortIfStatementsOnASingleLine = true;
+  AllowsMergedIf.AllowShortIfStatementsOnASingleLine =
+      FormatStyle::SIS_WithoutElse;
   verifyFormat("void f() { f(); }\n#error E", AllowsMergedIf);
   verifyFormat("if (true) return 42;\n#error E", AllowsMergedIf);
   verifyFormat("if (true)\n#error E\n  return 42;", AllowsMergedIf);
   EXPECT_EQ("if (true) return 42;",
             format("if (true)\nreturn 42;", AllowsMergedIf));
   FormatStyle ShortMergedIf = AllowsMergedIf;
   ShortMergedIf.ColumnLimit = 25;
   verifyFormat("#define A \\\n"
TEST_F(FormatTest, AllmanBraceBreaking) {
   verifyFormat("void f()\n"
                "{\n"
                "  int i;\n"
                "}",
                AllmanBraceStyle);
   AllmanBraceStyle.ColumnLimit = 80;
 
   FormatStyle BreakBeforeBraceShortIfs = AllmanBraceStyle;
-  BreakBeforeBraceShortIfs.AllowShortIfStatementsOnASingleLine = true;
+  BreakBeforeBraceShortIfs.AllowShortIfStatementsOnASingleLine =
+      FormatStyle::SIS_WithoutElse;
   BreakBeforeBraceShortIfs.AllowShortLoopsOnASingleLine = true;
   verifyFormat("void f(bool b)\n"
                "{\n"
                "  if (b)\n"
                "  {\n"
                "    return;\n"
                "  }\n"
                "}\n",
TEST_F(FormatTest, ParsesConfigurationBools) {
   Style.Language = FormatStyle::LK_Cpp;
   CHECK_PARSE_BOOL(AlignOperands);
   CHECK_PARSE_BOOL(AlignTrailingComments);
   CHECK_PARSE_BOOL(AlignConsecutiveAssignments);
   CHECK_PARSE_BOOL(AlignConsecutiveDeclarations);
   CHECK_PARSE_BOOL(AllowAllParametersOfDeclarationOnNextLine);
   CHECK_PARSE_BOOL(AllowShortBlocksOnASingleLine);
   CHECK_PARSE_BOOL(AllowShortCaseLabelsOnASingleLine);
-  CHECK_PARSE_BOOL(AllowShortIfStatementsOnASingleLine);
   CHECK_PARSE_BOOL(AllowShortLoopsOnASingleLine);
   CHECK_PARSE_BOOL(BinPackArguments);
   CHECK_PARSE_BOOL(BinPackParameters);
   CHECK_PARSE_BOOL(BreakAfterJavaFieldAnnotations);
   CHECK_PARSE_BOOL(BreakBeforeTernaryOperators);
   CHECK_PARSE_BOOL(BreakStringLiterals);
   CHECK_PARSE_BOOL(CompactNamespaces);
   CHECK_PARSE_BOOL(ConstructorInitializerAllOnOneLineOrOnePerLine);
TEST_F(FormatTest, ParsesConfiguration) {
   Style.NamespaceIndentation = FormatStyle::NI_All;
   CHECK_PARSE("NamespaceIndentation: None", NamespaceIndentation,
               FormatStyle::NI_None);
   CHECK_PARSE("NamespaceIndentation: Inner", NamespaceIndentation,
               FormatStyle::NI_Inner);
   CHECK_PARSE("NamespaceIndentation: All", NamespaceIndentation,
               FormatStyle::NI_All);
 
+  Style.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_Always;
+  CHECK_PARSE("AllowShortIfStatementsOnASingleLine: Never",
+              AllowShortIfStatementsOnASingleLine, FormatStyle::SIS_Never);
+  CHECK_PARSE("AllowShortIfStatementsOnASingleLine: WithoutElse",
+              AllowShortIfStatementsOnASingleLine,
+              FormatStyle::SIS_WithoutElse);
+  CHECK_PARSE("AllowShortIfStatementsOnASingleLine: Always",
+              AllowShortIfStatementsOnASingleLine, FormatStyle::SIS_Always);
+  CHECK_PARSE("AllowShortIfStatementsOnASingleLine: false",
+              AllowShortIfStatementsOnASingleLine, FormatStyle::SIS_Never);
+  CHECK_PARSE("AllowShortIfStatementsOnASingleLine: true",
+              AllowShortIfStatementsOnASingleLine,
+              FormatStyle::SIS_WithoutElse);
+
   // FIXME: This is required because parsing a configuration simply overwrites
   // the first N elements of the list instead of resetting it.
   Style.ForEachMacros.clear();
   std::vector<std::string> BoostForeach;
   BoostForeach.push_back("BOOST_FOREACH");
   CHECK_PARSE("ForEachMacros: [BOOST_FOREACH]", ForEachMacros, BoostForeach);
   std::vector<std::string> BoostAndQForeach;
   BoostAndQForeach.push_back("BOOST_FOREACH");

cfe/trunk/unittests/Format/FormatTestSelective.cpp

EXPECT_EQ(
       format(
           "template<typename T>\n"
           "T *getFETokenInfo() const { return static_cast<T*>(FETokenInfo); }\n"
           "int  a; // <- Should not be formatted",
           9, 5));
 }
 
 TEST_F(FormatTestSelective, FormatsIfWithoutCompoundStatement) {
-  Style.AllowShortIfStatementsOnASingleLine = true;
+  Style.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_WithoutElse;
   EXPECT_EQ("if (a) return;", format("if(a)\nreturn;", 7, 1));
   EXPECT_EQ("if (a) return; // comment",
             format("if(a)\nreturn; // comment", 20, 1));
 }
 
 TEST_F(FormatTestSelective, FormatsCommentsLocally) {
   EXPECT_EQ("int a;    // comment\n"
             "int    b; // comment",