[clang-format] Fix regression about not aligning trailing comments in case they were previously aligned, but at different indent.

[krasimir]

Summary

Comment reflower was adding untouchable tokens in case two consecutive comment lines are aligned in the source code. This disallows the whitespace manager to re-indent them later.

source:

int i = f(abc, // line 1
          d, // line 2
	     // line 3
	  b);

Since line 2 and line 3 are aligned, the reflower was marking line 3 as untouchable; however the three comment lines need to be re-aligned.
output before:

int i = f(abc, // line 1
          d,   // line 2
	     // line 3
	  b);

output after:

int i = f(abc, // line 1
          d,   // line 2
	       // line 3
	  b);

[djasper]

Looks good

lib/Format/BreakableToken.cpp

if (SplitBefore.first != StringRef::npos) {
       // previous token is necessary. However, we still may need to adjust the
       // start column. Note that ContentColumn[LineIndex] is the expected
       // content column after a possible update to the prefix, hence the prefix
       // length change is included.
       unsigned LineColumn =
           ContentColumn[LineIndex] -
           (Content[LineIndex].data() - Lines[LineIndex].data()) +
           (OriginalPrefix[LineIndex].size() - Prefix[LineIndex].size());
-      if (tokenAt(LineIndex).OriginalColumn != LineColumn) {
-        Whitespaces.replaceWhitespace(*Tokens[LineIndex],
-                                      /*Newlines=*/1,
-                                      /*Spaces=*/LineColumn,
-                                      /*StartOfTokenColumn=*/LineColumn,
-                                      /*InPPDirective=*/false);
-      } else {
-        // The whitespace preceding the first line of this token does not need
-        // to be touched.
-        Whitespaces.addUntouchableToken(tokenAt(LineIndex),
-                                        /*InPPDirective=*/false);
-      }
+
+      // We always want to create a replacement instead of adding an untouchable
+      // token, even if LineColumn is the same as the original column of the
+      // token. This is because WhitespaceManager doesn't align trailing
+      // comments if they are untouchable.
     }
   }
   if (OriginalPrefix[LineIndex] != Prefix[LineIndex]) {
     // Adjust the prefix if necessary.
 
     // Take care of the space possibly introduced after a decoration.
     assert(Prefix[LineIndex] == (OriginalPrefix[LineIndex] + " ").str() &&
            "Expecting a line comment prefix to differ from original by at most "

unittests/Format/FormatTest.cpp

EXPECT_EQ("/* First comment\n"
                    "/* Snd\n"
                    " */\n",
                    getLLVMStyleWithColumns(20)));
 
   // Don't reflow across blank comment lines.
   EXPECT_EQ("int i; // This long\n"
             "       // line gets\n"
             "       // broken.\n"
-            "       //  \n"
+            "       //\n"
             "       // keep.\n",
             format("int i; // This long line gets broken.\n"
                    "       //  \n"
                    "       // keep.\n",
                    getLLVMStyleWithColumns(20)));
   EXPECT_EQ("{\n"
             "  /// long long long\n"
             "  /// long long\n"
TEST_F(ReplacementTest, SortIncludesAfterReplacement) {
   auto FormattedReplaces = formatReplacements(Code, Replaces, Style);
   EXPECT_TRUE(static_cast<bool>(FormattedReplaces))
       << llvm::toString(FormattedReplaces.takeError()) << "\n";
   auto Result = applyAllReplacements(Code, *FormattedReplaces);
   EXPECT_TRUE(static_cast<bool>(Result));
   EXPECT_EQ(Expected, *Result);
 }
 
-TEST_F(FormatTest, AllignTrailingComments) {
+TEST_F(FormatTest, AlignTrailingComments) {
   EXPECT_EQ("#define MACRO(V)                       \\\n"
             "  V(Rt2) /* one more char */           \\\n"
             "  V(Rs)  /* than here  */              \\\n"
             "/* comment 3 */\n",
             format("#define MACRO(V)\\\n"
                    "V(Rt2)  /* one more char */ \\\n"
                    "V(Rs) /* than here  */    \\\n"
                    "/* comment 3 */         \\\n",
                    getLLVMStyleWithColumns(40)));
+  EXPECT_EQ("int i = f(abc, // line 1\n"
+            "          d,   // line 2\n"
+            "               // line 3\n"
+            "          b);",
+            format("int i = f(abc, // line 1\n"
+                   "          d, // line 2\n"
+                   "             // line 3\n"
+                   "          b);",
+                   getLLVMStyleWithColumns(40)));
 }
 } // end namespace
 } // end namespace format
 } // end namespace clang