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

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

Reviewers: klimek, djasper, JonasToth, alexfh, krasimir, reuk
Reviewed By: reuk
Subscribers: reuk, Higuoxing, jdoerfert, cfe-commits
Tags: #clang-tools-extra
Differential Revision: https://reviews.llvm.org/D59087

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@356029 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 39 insertions, 2 deletions

diff --git a/docs/ClangFormatStyleOptions.rst b/docs/ClangFormatStyleOptions.rst
index 582b9d938c..d4a56d3bb3 100644
--- a/docs/ClangFormatStyleOptions.rst
+++ b/docs/ClangFormatStyleOptions.rst
@@ -365,10 +365,47 @@ the configuration (without a prefix: ``Auto``).
       };
       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