[clang-format] PR48594 BraceWrapping: SplitEmptyRecord ignored for te…

…mplates

https://bugs.llvm.org/show_bug.cgi?id=48594

Empty or small templates were not being treated the same way as small classes especially when SplitEmptyRecord was set to true

This revision aims to help this by identifying a case when we should try not to merge the lines together

Reviewed By: curdeius, JohelEGP

Differential Revision: https://reviews.llvm.org/D93839

clang/lib/Format/UnwrappedLineFormatter.cpp

@@ -248,6 +248,11 @@ class LineJoiner {
         return !Style.BraceWrapping.SplitEmptyRecord && EmptyBlock
                    ? tryMergeSimpleBlock(I, E, Limit)
                    : 0;
+
+      if (Tok && Tok->is(tok::kw_template) &&
+          Style.BraceWrapping.SplitEmptyRecord && EmptyBlock) {
+        return 0;
+      }
     }
 
     // FIXME: TheLine->Level != 0 might or might not be the right check to do.
@@ -355,6 +360,30 @@ class LineJoiner {
     if (TheLine->First->is(tok::l_brace) && I != AnnotatedLines.begin() &&
         I[-1]->First->isOneOf(tok::kw_case, tok::kw_default))
       return 0;
+
+    // Don't merge an empty template class or struct if SplitEmptyRecords
+    // is defined.
+    if (Style.BraceWrapping.SplitEmptyRecord &&
+        TheLine->Last->is(tok::l_brace) && I != AnnotatedLines.begin() &&
+        I[-1]->Last) {
+      const FormatToken *Previous = I[-1]->Last;
+      if (Previous) {
+        if (Previous->is(tok::comment))
+          Previous = Previous->getPreviousNonComment();
+        if (Previous) {
+          if (Previous->is(tok::greater))
+            return 0;
+          if (Previous->is(tok::identifier)) {
+            const FormatToken *PreviousPrevious =
+                Previous->getPreviousNonComment();
+            if (PreviousPrevious &&
+                PreviousPrevious->isOneOf(tok::kw_class, tok::kw_struct))
+              return 0;
+          }
+        }
+      }
+    }
+
     // Try to merge a block with left brace wrapped that wasn't yet covered
     if (TheLine->Last->is(tok::l_brace)) {
       return !Style.BraceWrapping.AfterFunction ||

clang/unittests/Format/FormatTest.cpp

@@ -9891,6 +9891,71 @@ TEST_F(FormatTest, SplitEmptyClass) {
                "{\n"
                "} Foo_t;",
                Style);
+
+  Style.BraceWrapping.SplitEmptyRecord = true;
+  Style.BraceWrapping.AfterStruct = true;
+  verifyFormat("class rep\n"
+               "{\n"
+               "};",
+               Style);
+  verifyFormat("struct rep\n"
+               "{\n"
+               "};",
+               Style);
+  verifyFormat("template <typename T> class rep\n"
+               "{\n"
+               "};",
+               Style);
+  verifyFormat("template <typename T> struct rep\n"
+               "{\n"
+               "};",
+               Style);
+  verifyFormat("class rep\n"
+               "{\n"
+               "  int x;\n"
+               "};",
+               Style);
+  verifyFormat("struct rep\n"
+               "{\n"
+               "  int x;\n"
+               "};",
+               Style);
+  verifyFormat("template <typename T> class rep\n"
+               "{\n"
+               "  int x;\n"
+               "};",
+               Style);
+  verifyFormat("template <typename T> struct rep\n"
+               "{\n"
+               "  int x;\n"
+               "};",
+               Style);
+  verifyFormat("template <typename T> class rep // Foo\n"
+               "{\n"
+               "  int x;\n"
+               "};",
+               Style);
+  verifyFormat("template <typename T> struct rep // Bar\n"
+               "{\n"
+               "  int x;\n"
+               "};",
+               Style);
+
+  verifyFormat("template <typename T> class rep<T>\n"
+               "{\n"
+               "  int x;\n"
+               "};",
+               Style);
+
+  verifyFormat("template <typename T> class rep<std::complex<T>>\n"
+               "{\n"
+               "  int x;\n"
+               "};",
+               Style);
+  verifyFormat("template <typename T> class rep<std::complex<T>>\n"
+               "{\n"
+               "};",
+               Style);
 }
 
 TEST_F(FormatTest, SplitEmptyStruct) {

clang/unittests/Format/FormatTestCSharp.cpp

@@ -835,25 +835,27 @@ if (someThings[i][j][k].Contains(myThing)) {
 TEST_F(FormatTestCSharp, CSharpGenericTypeConstraints) {
   FormatStyle Style = getGoogleStyle(FormatStyle::LK_CSharp);
 
-  verifyFormat(R"(//
-class ItemFactory<T>
-    where T : new() {})",
+  EXPECT_TRUE(Style.BraceWrapping.SplitEmptyRecord);
+
+  verifyFormat("class ItemFactory<T>\n"
+               "    where T : new() {\n"
+               "}",
                Style);
 
-  verifyFormat(R"(//
-class Dictionary<TKey, TVal>
-    where TKey : IComparable<TKey>
-    where TVal : IMyInterface {
-  public void MyMethod<T>(T t)
-      where T : IMyInterface {
-    doThing();
-  }
-})",
+  verifyFormat("class Dictionary<TKey, TVal>\n"
+               "    where TKey : IComparable<TKey>\n"
+               "    where TVal : IMyInterface {\n"
+               "  public void MyMethod<T>(T t)\n"
+               "      where T : IMyInterface {\n"
+               "    doThing();\n"
+               "  }\n"
+               "}",
                Style);
 
-  verifyFormat(R"(//
-class ItemFactory<T>
-    where T : new(), IAnInterface<T>, IAnotherInterface<T>, IAnotherInterfaceStill<T> {})",
+  verifyFormat("class ItemFactory<T>\n"
+               "    where T : new(), IAnInterface<T>, IAnotherInterface<T>, "
+               "IAnotherInterfaceStill<T> {\n"
+               "}",
                Style);
 
   Style.ColumnLimit = 50; // Force lines to be wrapped.
@@ -862,7 +864,8 @@ class ItemFactory<T, U>
     where T : new(),
               IAnInterface<T>,
               IAnotherInterface<T, U>,
-              IAnotherInterfaceStill<T, U> {})",
+              IAnotherInterfaceStill<T, U> {
+})",
                Style);
 
   // In other languages `where` can be used as a normal identifier.