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[clang-format] Fixing erroneous trailing comma #205631

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Merged
HazardyKnusperkeks merged 3 commits into from
Jun 26, 2026
Merged

[clang-format] Fixing erroneous trailing comma #205631

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f031aab
[clang-format] Fixing erroneous trailing comma
brevzin-jumptrading Jun 24, 2026
a507b8a
Skipping duplicates earlier
brevzin-jumptrading Jun 24, 2026
2693efe
Properly fix it
HazardyKnusperkeks Jun 25, 2026
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6 changes: 6 additions & 0 deletions clang/lib/Tooling/Core/Replacement.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -270,6 +270,12 @@ llvm::Error Replacements::add(const Replacement &R) {
assert(R.getLength() == 0);
// `I` is also an insertion, `R` and `I` conflict.
if (I->getLength() == 0) {
// If the two insertions are identical, `R` is redundant; keep the
// existing one rather than concatenating. This happens e.g. when
// clang-format analyzes the same code under several preprocessor
// branches and emits the same insertion in each run.
if (R.getReplacementText() == I->getReplacementText())

@HazardyKnusperkeks HazardyKnusperkeks Jun 24, 2026

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This fixes the symptom, while the root cause is kept. I'm currently not that fit in the preprocessor branches stuff, but it would be nice if we can fix it there. It it outside of the branches and an unwrapped line on itself.

return llvm::Error::success();
// Check if two insertions are order-independent: if inserting them in
// either order produces the same text, they are order-independent.
if ((R.getReplacementText() + I->getReplacementText()).str() !=
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13 changes: 13 additions & 0 deletions clang/unittests/Format/FormatTest.cpp
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Expand Up @@ -25210,6 +25210,19 @@ TEST_F(FormatTest, EnumTrailingComma) {
" MY_ENUM = 0U\n"
"};",
Style);

// Issue https://github.com/llvm/llvm-project/issues/205571
verifyFormat("#ifdef FOO\n"
"#else\n"
"#endif\n"
"enum {\n"
" E = 1,\n"
"};",
"#ifdef FOO\n"
"#else\n"
"#endif\n"
"enum { E = 1 };",
Style);
}

TEST_F(FormatTest, BreakAfterAttributes) {
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12 changes: 12 additions & 0 deletions clang/unittests/Tooling/RefactoringTest.cpp
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Expand Up @@ -416,6 +416,18 @@ TEST_F(ReplacementTest, AddInsertAtOtherInsertWhenOderIndependent) {
EXPECT_EQ(Replacement("x.cc", 10, 3, ""), *std::next(Replaces.begin()));
}

TEST_F(ReplacementTest, AddIdenticalInsertionsAtSameOffsetDeduplicates) {
Replacements Replaces;
auto Err = Replaces.add(Replacement("x.cc", 10, 0, ","));
EXPECT_TRUE(!Err);
llvm::consumeError(std::move(Err));
Err = Replaces.add(Replacement("x.cc", 10, 0, ","));
EXPECT_TRUE(!Err);
llvm::consumeError(std::move(Err));
EXPECT_EQ(1u, Replaces.size());
EXPECT_EQ(Replacement("x.cc", 10, 0, ","), *Replaces.begin());
}

TEST_F(ReplacementTest, InsertBetweenAdjacentReplacements) {
Replacements Replaces;
auto Err = Replaces.add(Replacement("x.cc", 10, 5, "a"));
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