clang-format: Add CompactNamespaces option

Summary:
Add CompactNamespaces option, to pack namespace declarations on the
same line (somewhat similar to C++17 nested namespace definition).

With this option, consecutive namespace declarations are kept on the
same line:

  namespace foo { namespace bar {
      ...
  }} // namespace foo::bar

Reviewers: krasimir, djasper, klimek

Reviewed By: djasper

Subscribers: kimgr, cfe-commits, klimek

Tags: #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D32480

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@305384 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 192 insertions, 0 deletions

diff --git a/unittests/Format/FormatTest.cpp b/unittests/Format/FormatTest.cpp
index 783fe45042..f493717103 100644
--- a/unittests/Format/FormatTest.cpp
+++ b/unittests/Format/FormatTest.cpp
@@ -1310,6 +1310,141 @@ TEST_F(FormatTest, FormatsNamespaces) {
                    Style));
 }
 
+TEST_F(FormatTest, FormatsCompactNamespaces) {
+  FormatStyle Style = getLLVMStyle();
+  Style.CompactNamespaces = true;
+
+  verifyFormat("namespace A { namespace B {\n"
+			   "}} // namespace A::B",
+			   Style);
+
+  EXPECT_EQ("namespace out { namespace in {\n"
+            "}} // namespace out::in",
+            format("namespace out {\n"
+                   "namespace in {\n"
+                   "} // namespace in\n"
+                   "} // namespace out",
+                   Style));
+
+  // Only namespaces which have both consecutive opening and end get compacted
+  EXPECT_EQ("namespace out {\n"
+            "namespace in1 {\n"
+            "} // namespace in1\n"
+            "namespace in2 {\n"
+            "} // namespace in2\n"
+            "} // namespace out",
+            format("namespace out {\n"
+                   "namespace in1 {\n"
+                   "} // namespace in1\n"
+                   "namespace in2 {\n"
+                   "} // namespace in2\n"
+                   "} // namespace out",
+                   Style));
+
+  EXPECT_EQ("namespace out {\n"
+            "int i;\n"
+            "namespace in {\n"
+            "int j;\n"
+            "} // namespace in\n"
+            "int k;\n"
+            "} // namespace out",
+            format("namespace out { int i;\n"
+                   "namespace in { int j; } // namespace in\n"
+                   "int k; } // namespace out",
+                   Style));
+
+  EXPECT_EQ("namespace A { namespace B { namespace C {\n"
+            "}}} // namespace A::B::C\n",
+            format("namespace A { namespace B {\n"
+                   "namespace C {\n"
+                   "}} // namespace B::C\n"
+                   "} // namespace A\n",
+                   Style));
+
+  Style.ColumnLimit = 40;
+  EXPECT_EQ("namespace aaaaaaaaaa {\n"
+            "namespace bbbbbbbbbb {\n"
+            "}} // namespace aaaaaaaaaa::bbbbbbbbbb",
+            format("namespace aaaaaaaaaa {\n"
+                   "namespace bbbbbbbbbb {\n"
+                   "} // namespace bbbbbbbbbb\n"
+                   "} // namespace aaaaaaaaaa",
+                   Style));
+
+  EXPECT_EQ("namespace aaaaaa { namespace bbbbbb {\n"
+            "namespace cccccc {\n"
+            "}}} // namespace aaaaaa::bbbbbb::cccccc",
+            format("namespace aaaaaa {\n"
+                   "namespace bbbbbb {\n"
+                   "namespace cccccc {\n"
+                   "} // namespace cccccc\n"
+                   "} // namespace bbbbbb\n"
+                   "} // namespace aaaaaa",
+                   Style));
+  Style.ColumnLimit = 80;
+
+  // Extra semicolon after 'inner' closing brace prevents merging
+  EXPECT_EQ("namespace out { namespace in {\n"
+            "}; } // namespace out::in",
+            format("namespace out {\n"
+                   "namespace in {\n"
+                   "}; // namespace in\n"
+                   "} // namespace out",
+                   Style));
+
+  // Extra semicolon after 'outer' closing brace is conserved
+  EXPECT_EQ("namespace out { namespace in {\n"
+            "}}; // namespace out::in",
+            format("namespace out {\n"
+                   "namespace in {\n"
+                   "} // namespace in\n"
+                   "}; // namespace out",
+                   Style));
+
+  Style.NamespaceIndentation = FormatStyle::NI_All;
+  EXPECT_EQ("namespace out { namespace in {\n"
+            "  int i;\n"
+            "}} // namespace out::in",
+            format("namespace out {\n"
+                   "namespace in {\n"
+                   "int i;\n"
+                   "} // namespace in\n"
+                   "} // namespace out",
+                   Style));
+  EXPECT_EQ("namespace out { namespace mid {\n"
+            "  namespace in {\n"
+            "    int j;\n"
+            "  } // namespace in\n"
+            "  int k;\n"
+            "}} // namespace out::mid",
+            format("namespace out { namespace mid {\n"
+                   "namespace in { int j; } // namespace in\n"
+                   "int k; }} // namespace out::mid",
+                   Style));
+
+  Style.NamespaceIndentation = FormatStyle::NI_Inner;
+  EXPECT_EQ("namespace out { namespace in {\n"
+            "  int i;\n"
+            "}} // namespace out::in",
+            format("namespace out {\n"
+                   "namespace in {\n"
+                   "int i;\n"
+                   "} // namespace in\n"
+                   "} // namespace out",
+                   Style));
+  EXPECT_EQ("namespace out { namespace mid { namespace in {\n"
+            "  int i;\n"
+            "}}} // namespace out::mid::in",
+            format("namespace out {\n"
+                   "namespace mid {\n"
+                   "namespace in {\n"
+                   "int i;\n"
+                   "} // namespace in\n"
+                   "} // namespace mid\n"
+                   "} // namespace out",
+                   Style));
+}
+
 TEST_F(FormatTest, FormatsExternC) { verifyFormat("extern \"C\" {\nint a;"); }
 
 TEST_F(FormatTest, FormatsInlineASM) {
@@ -9051,6 +9186,7 @@ TEST_F(FormatTest, ParsesConfigurationBools) {
   CHECK_PARSE_BOOL(BreakBeforeTernaryOperators);
   CHECK_PARSE_BOOL(BreakStringLiterals);
   CHECK_PARSE_BOOL(BreakBeforeInheritanceComma)
+  CHECK_PARSE_BOOL(CompactNamespaces);
   CHECK_PARSE_BOOL(ConstructorInitializerAllOnOneLineOrOnePerLine);
   CHECK_PARSE_BOOL(DerivePointerAlignment);
   CHECK_PARSE_BOOL_FIELD(DerivePointerAlignment, "DerivePointerBinding");
diff --git a/unittests/Format/NamespaceEndCommentsFixerTest.cpp b/unittests/Format/NamespaceEndCommentsFixerTest.cpp
index 6c2d369852..92f3421629 100644
--- a/unittests/Format/NamespaceEndCommentsFixerTest.cpp
+++ b/unittests/Format/NamespaceEndCommentsFixerTest.cpp
@@ -185,6 +185,41 @@ TEST_F(NamespaceEndCommentsFixerTest, AddsEndComment) {
                                     "}\n"
                                     "}"));
 
+  // Add comment for namespaces which will be 'compacted'
+  FormatStyle CompactNamespacesStyle = getLLVMStyle();
+  CompactNamespacesStyle.CompactNamespaces = true;
+  EXPECT_EQ("namespace out { namespace in {\n"
+            "int i;\n"
+            "int j;\n"
+            "}}// namespace out::in",
+            fixNamespaceEndComments("namespace out { namespace in {\n"
+                                    "int i;\n"
+                                    "int j;\n"
+                                    "}}",
+                                    CompactNamespacesStyle));
+  EXPECT_EQ("namespace out {\n"
+            "namespace in {\n"
+            "int i;\n"
+            "int j;\n"
+            "}\n"
+            "}// namespace out::in",
+            fixNamespaceEndComments("namespace out {\n"
+                                    "namespace in {\n"
+                                    "int i;\n"
+                                    "int j;\n"
+                                    "}\n"
+                                    "}",
+                                    CompactNamespacesStyle));
+  EXPECT_EQ("namespace out { namespace in {\n"
+            "int i;\n"
+            "int j;\n"
+            "};}// namespace out::in",
+            fixNamespaceEndComments("namespace out { namespace in {\n"
+                                    "int i;\n"
+                                    "int j;\n"
+                                    "};}",
+                                    CompactNamespacesStyle));
+
   // Adds an end comment after a semicolon.
   EXPECT_EQ("namespace {\n"
             "  int i;\n"
@@ -388,6 +423,27 @@ TEST_F(NamespaceEndCommentsFixerTest, UpdatesInvalidEndLineComment) {
             fixNamespaceEndComments("namespace A {} // namespace"));
   EXPECT_EQ("namespace A {}; // namespace A",
             fixNamespaceEndComments("namespace A {}; // namespace"));
+
+  // Update invalid comments for compacted namespaces.
+  FormatStyle CompactNamespacesStyle = getLLVMStyle();
+  CompactNamespacesStyle.CompactNamespaces = true;
+  EXPECT_EQ("namespace out { namespace in {\n"
+            "}} // namespace out::in",
+            fixNamespaceEndComments("namespace out { namespace in {\n"
+                                    "}} // namespace out",
+                                    CompactNamespacesStyle));
+  EXPECT_EQ("namespace out { namespace in {\n"
+            "}} // namespace out::in",
+            fixNamespaceEndComments("namespace out { namespace in {\n"
+                                    "}} // namespace in",
+                                    CompactNamespacesStyle));
+  EXPECT_EQ("namespace out { namespace in {\n"
+            "}\n"
+            "} // namespace out::in",
+            fixNamespaceEndComments("namespace out { namespace in {\n"
+                                    "}// banamespace in\n"
+                                    "} // namespace out",
+                                    CompactNamespacesStyle));
 }
 
 TEST_F(NamespaceEndCommentsFixerTest, UpdatesInvalidEndBlockComment) {