[clang-format] Align trailing comments for function parameters

[sstwcw]

before

void foo(int   name, // name
         float name, // name
         int   name)   // name
{}

after

void foo(int   name, // name
         float name, // name
         int   name) // name
{}

Fixes #85123.

As the bug report explained, the procedure for aligning the function parameters previously failed to update StartOfTokenColumn.

[llvmbot]

@llvm/pr-subscribers-clang-format

Author: None (sstwcw)

Changes

before

void foo(int   name, // name
         float name, // name
         int   name)   // name
{}

after

void foo(int   name, // name
         float name, // name
         int   name) // name
{}

Fixes #85123.

As the bug report explained, the procedure for aligning the function parameters previously failed to update StartOfTokenColumn.

---

Full diff: https://github.com/llvm/llvm-project/pull/164458.diff

2 Files Affected:

• (modified) clang/lib/Format/WhitespaceManager.cpp (+7)
• (modified) clang/unittests/Format/FormatTest.cpp (+8)

diff --git a/clang/lib/Format/WhitespaceManager.cpp b/clang/lib/Format/WhitespaceManager.cpp
index 65fc65e79fdc3..b9a261c9e91d2 100644
--- a/clang/lib/Format/WhitespaceManager.cpp
+++ b/clang/lib/Format/WhitespaceManager.cpp
@@ -399,6 +399,13 @@ AlignTokenSequence(const FormatStyle &Style, unsigned Start, unsigned End,
       }
     }
   }
+
+  // The scope to be aligned may not occupy entire lines. The rest of the line
+  // needs some book-keeping.
+  for (unsigned i = End; i < Changes.size() && Changes[i].NewlinesBefore == 0;
+       ++i) {
+    Changes[i].StartOfTokenColumn += Shift;
+  }
 }
 
 // Walk through a subset of the changes, starting at StartAt, and find
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index ce68f91bef02a..9133eeb137cb9 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -19828,6 +19828,14 @@ TEST_F(FormatTest, AlignConsecutiveDeclarations) {
                "  Test &operator=(const Test &) = default;\n"
                "};",
                Alignment);
+
+  // The comment to the right should still align right.
+  verifyFormat("void foo(int   name, // name\n"
+               "         float name, // name\n"
+               "         int   name) // name\n"
+               "{}",
+               Alignment);
+
   unsigned OldColumnLimit = Alignment.ColumnLimit;
   // We need to set ColumnLimit to zero, in order to stress nested alignments,
   // otherwise the function parameters will be re-flowed onto a single line.