[PATCH] D59087: [clang-format] [PR25010] AllowShortIfStatementsOnASingleLine not working if an "else" statement is present

[MyDeveloperDay via Phabricator via cfe-commits]

MyDeveloperDay created this revision.
MyDeveloperDay added reviewers: klimek, djasper, JonasToth, alexfh, krasimir.
MyDeveloperDay added a project: clang-tools-extra.
Herald added a subscriber: jdoerfert.

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


https://reviews.llvm.org/D59087

Files:
  clang/docs/ClangFormatStyleOptions.rst
  clang/lib/Format/Format.cpp
  clang/lib/Format/UnwrappedLineFormatter.cpp
  clang/unittests/Format/FormatTest.cpp


Index: clang/unittests/Format/FormatTest.cpp
===================================================================
--- clang/unittests/Format/FormatTest.cpp
+++ clang/unittests/Format/FormatTest.cpp
@@ -487,6 +487,34 @@
   verifyFormat("if (a)\n  return;", AllowsMergedIf);
 }
 
+TEST_F(FormatTest, FormatIfWithoutCompoundStatementButElseWith) {
+  FormatStyle AllowsMergedIf = getLLVMStyle();
+  AllowsMergedIf.AlignEscapedNewlines = FormatStyle::ENAS_Left;
+  AllowsMergedIf.AllowShortIfStatementsOnASingleLine = true;
+  verifyFormat("if (a)\n"
+               "  f();\n"
+               "else {\n"
+               "  g();\n"
+               "}",
+               AllowsMergedIf);
+
+  AllowsMergedIf.AllowShortIfElseStatementsOnASingleLine = true;
+  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;
Index: clang/lib/Format/UnwrappedLineFormatter.cpp
===================================================================
--- clang/lib/Format/UnwrappedLineFormatter.cpp
+++ clang/lib/Format/UnwrappedLineFormatter.cpp
@@ -413,10 +413,12 @@
     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).
-    if (I + 2 != E && Line.startsWith(tok::kw_if) &&
-        I[2]->First->is(tok::kw_else))
-      return 0;
+    // Only inline simple if's (no nested if or else), unless specified
+    if (!Style.AllowShortIfElseStatementsOnASingleLine) {
+      if (I + 2 != E && Line.startsWith(tok::kw_if) &&
+          I[2]->First->is(tok::kw_else))
+        return 0;
+    }
     return 1;
   }
 
Index: clang/lib/Format/Format.cpp
===================================================================
--- clang/lib/Format/Format.cpp
+++ clang/lib/Format/Format.cpp
@@ -331,6 +331,8 @@
                    Style.AllowShortFunctionsOnASingleLine);
     IO.mapOptional("AllowShortIfStatementsOnASingleLine",
                    Style.AllowShortIfStatementsOnASingleLine);
+    IO.mapOptional("AllowShortIfElseStatementsOnASingleLine",
+                   Style.AllowShortIfElseStatementsOnASingleLine);
     IO.mapOptional("AllowShortLoopsOnASingleLine",
                    Style.AllowShortLoopsOnASingleLine);
     IO.mapOptional("AlwaysBreakAfterDefinitionReturnType",
@@ -632,6 +634,7 @@
   LLVMStyle.AllowShortBlocksOnASingleLine = false;
   LLVMStyle.AllowShortCaseLabelsOnASingleLine = false;
   LLVMStyle.AllowShortIfStatementsOnASingleLine = false;
+  LLVMStyle.AllowShortIfElseStatementsOnASingleLine = false;
   LLVMStyle.AllowShortLoopsOnASingleLine = false;
   LLVMStyle.AlwaysBreakAfterReturnType = FormatStyle::RTBS_None;
   LLVMStyle.AlwaysBreakAfterDefinitionReturnType = FormatStyle::DRTBS_None;
Index: clang/docs/ClangFormatStyleOptions.rst
===================================================================
--- clang/docs/ClangFormatStyleOptions.rst
+++ clang/docs/ClangFormatStyleOptions.rst
@@ -365,11 +365,27 @@
       };
       void f() { bar(); }
 
-
-
 **AllowShortIfStatementsOnASingleLine** (``bool``)
   If ``true``, ``if (a) return;`` can be put on a single line.
 
+  .. code-block:: c++
+
+       if (a) return;
+       else 
+         return;
+
+**AllowShortIfElseStatementsOnASingleLine** (``bool``)
+  When used in conjuction with ``AllowShortIfIfStatementsOnASingleLine``
+  then when ``true``, ``if (a) return;`` can be put on a single even when
+  the else clause 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.

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