Fix extraneous whitespace addition in line comments on clang-format directives

[penagos]

Summary

Fixes https://github.com/llvm/llvm-project/issues/53844.
I believe this regression was caused by not accounting for clang-format directives in https://reviews.llvm.org/D92257.

[HazardyKnusperkeks]

clang/lib/Format/BreakableToken.cpp

817–825

This slowly gets hard to read. Could you maybe split it up? Either in giving the multiple parts their own name. Or to keep the short circuiting have something like:

auto AllowsSpaceChange = ...;
AllowsSpaceChange = AllowsSpaceChange || ...;
AllowsSpaceChange = AllowsSpaceChange || ...;

clang/unittests/Format/FormatTestComments.cpp

98

Why the limit?

[HazardyKnusperkeks]

Thanks for working on it.

[curdeius]

clang/lib/Format/BreakableToken.cpp

817–818

While here, please change auto to bool.

817–825

Or use a lambda (with a series of ifs for instance) to initialize it.

[penagos]

• Split AllowsSpaceChange conditional over multiple variables to enhance readability.
• Remove unnecessary column limit from unittest.

[penagos]

clang/lib/Format/BreakableToken.cpp

817–825

I've split the conditional over a couple of smaller boolean conditionals with the intent of enhancing readability.

clang/unittests/Format/FormatTestComments.cpp

98

This was a copy-paste artifact and wasn't intended to be included in the original diff; the column limit has no bearing on this specific test addition.

[penagos]

In D120188#3333674, @HazardyKnusperkeks wrote:

Thanks for working on it.

Happy to help!

[curdeius]

Great! Thanks a lot!
Do you have commit rights or you want someone to land it for you?
For the latter, we'll need your name and email for the commit attribution.

[penagos]

I don’t have commit rights; if someone could commit on my behalf that’d be great.

• Luis Penagos
• [e-mail]

Thanks!

clang/lib/Format/BreakableToken.cpp

for (size_t i = FirstLineIndex, e = Lines.size(); i < e; ++i) {
         PrefixSpaceChange[i] = FirstLineSpaceChange;
 
         if (SpacesInPrefix + PrefixSpaceChange[i] < Minimum) {
           PrefixSpaceChange[i] +=
               Minimum - (SpacesInPrefix + PrefixSpaceChange[i]);
         }
 
         assert(Lines[i].size() > IndentPrefix.size());
         const auto FirstNonSpace = Lines[i][IndentPrefix.size()];
-        const auto AllowsSpaceChange =
-            SpacesInPrefix != 0 ||
-            (!NoSpaceBeforeFirstCommentChar() ||
-             (FirstNonSpace == '}' && FirstLineSpaceChange != 0));
+        const bool IsFormatComment = LineTok && switchesFormatting(*LineTok);
+        const bool LineRequiresLeadingSpace =
+            !NoSpaceBeforeFirstCommentChar() ||
+            (FirstNonSpace == '}' && FirstLineSpaceChange != 0);
+        const bool AllowsSpaceChange =
+            !IsFormatComment &&
+            (SpacesInPrefix != 0 || LineRequiresLeadingSpace);
 
         if (PrefixSpaceChange[i] > 0 && AllowsSpaceChange) {
           Prefix[i] = IndentPrefix.str();
           Prefix[i].append(PrefixSpaceChange[i], ' ');
         } else if (PrefixSpaceChange[i] < 0 && AllowsSpaceChange) {
           Prefix[i] = IndentPrefix
                           .drop_back(std::min<std::size_t>(
                               -PrefixSpaceChange[i], SpacesInPrefix))
                           .str();

clang/unittests/Format/FormatTestComments.cpp

 //===----------------------------------------------------------------------===//
 
 TEST_F(FormatTestComments, UnderstandsSingleLineComments) {
   verifyFormat("//* */");
   verifyFormat("// line 1\n"
                "// line 2\n"
                "void f() {}\n");
 
+  EXPECT_EQ("// comment\n"
+            "// clang-format on\n",
+            format("//comment\n"
+                   "// clang-format on\n"));
+
   verifyFormat("void f() {\n"
                "  // Doesn't do anything\n"
                "}");
   verifyFormat("SomeObject\n"
                "    // Calling someFunction on SomeObject\n"
                "    .someFunction();");
   verifyFormat("auto result = SomeObject\n"
                "                  // Calling someFunction on SomeObject\n"