clang-format: Add special case for leading comments in braced lists.

A comment following the "{" of a braced list seems to almost always
refer to the first element of the list and thus should be aligned
to it.

Before (with Cpp11 braced list style):
  SomeFunction({  // Comment 1
                   "first entry",
                   // Comment 2
                   "second entry"});
After:
  SomeFunction({// Comment 1
                "first entry",
                // Comment 2
                "second entry"});

llvm-svn: 197725

1 files changed, 36 insertions, 8 deletions

diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index a56333d7783..cdf2f94cf3f 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -4771,12 +4771,12 @@ TEST_F(FormatTest, LayoutCxx11ConstructorBraceInitializers) {
     verifyFormat("DoSomethingWithVector({} /* No data */);");
     verifyFormat("DoSomethingWithVector({ {} /* No data */ }, { { 1, 2 } });");
     verifyFormat(
-        "someFunction(OtherParam, BracedList{\n"
-        "                           // comment 1 (Forcing interesting break)\n"
-        "                           param1, param2,\n"
-        "                           // comment 2\n"
-        "                           param3, param4\n"
-        "                         });");
+        "someFunction(OtherParam,\n"
+        "             BracedList{ // comment 1 (Forcing interesting break)\n"
+        "                         param1, param2,\n"
+        "                         // comment 2\n"
+        "                         param3, param4 });",
+        getLLVMStyleWithColumns(75));
     verifyFormat(
         "std::this_thread::sleep_for(\n"
         "    std::chrono::nanoseconds{ std::chrono::seconds{ 1 } } / 5);");
@@ -4808,11 +4808,39 @@ TEST_F(FormatTest, LayoutCxx11ConstructorBraceInitializers) {
                  "  T member = {arg1, arg2};\n"
                  "};",
                  NoSpaces);
+
+    // FIXME: The alignment of these trailing comments might be bad. Then again,
+    // this might be utterly useless in real code.
     verifyFormat("Constructor::Constructor()\n"
-                 "    : some_value{ //\n"
-                 "          aaaaaaa //\n"
+                 "    : some_value{        //\n"
+                 "                 aaaaaaa //\n"
                  "      } {}",
                  NoSpaces);
+
+    // In braced lists, the first comment is always assumed to belong to the
+    // first element. Thus, it can be moved to the next or previous line as
+    // appropriate.
+    EXPECT_EQ("function({// First element:\n"
+              "          1,\n"
+              "          // Second element:\n"
+              "          2});",
+              format("function({\n"
+                     "    // First element:\n"
+                     "    1,\n"
+                     "    // Second element:\n"
+                     "    2});",
+                     NoSpaces));
+    NoSpaces.ColumnLimit = 30;
+    EXPECT_EQ(
+  "std::vector<int> MyNumbers{\n"
+  "    // First element:\n"
+  "    1,\n"
+  "    // Second element:\n"
+  "    2};",
+  format("std::vector<int> MyNumbers{// First element:\n"
+  "                           1,\n"
+  "                           // Second element:\n"
+  "                           2};", NoSpaces));
 }
 
 TEST_F(FormatTest, FormatsBracedListsInColumnLayout) {