[clang] 5a4ddbd - [clang-format] [PR45639] clang-format splits up the brackets of C++17 attribute [[ ]] when used with the first parameter

[via cfe-commits]

Author: mydeveloperday
Date: 2020-05-07T22:00:04+01:00
New Revision: 5a4ddbd69db2b0e09398214510501d0e59a0c30b

URL: https://github.com/llvm/llvm-project/commit/5a4ddbd69db2b0e09398214510501d0e59a0c30b
DIFF: https://github.com/llvm/llvm-project/commit/5a4ddbd69db2b0e09398214510501d0e59a0c30b.diff

LOG: [clang-format] [PR45639] clang-format splits up the brackets of C++17 attribute [[ ]] when used with the first parameter

Summary:
https://bugs.llvm.org/show_bug.cgi?id=45639

clang-format incorrectly splits the `[[` in a long argument list

```
void SomeLongClassName::ALongMethodNameInThatClass([[maybe_unused]] const shared_ptr<ALongTypeName>& argumentNameForThat
LongType) {

}
```

becomes

```
void SomeLongClassName::ALongMethodNameInThatClass([
    [maybe_unused]] const shared_ptr<ALongTypeName> &argumentNameForThatLongType) {

}
```

leaving one `[` on the previous line

For a function with just 1 very long argument, clang-format chooses to split between the `[[`,

This revision prevents the slip between the two `[` and the second `[`

Reviewed By: krasimir

Subscribers: cfe-commits

Tags: #clang, #clang-format

Differential Revision: https://reviews.llvm.org/D79401

Added: 
    

Modified: 
    clang/lib/Format/TokenAnnotator.cpp
    clang/unittests/Format/FormatTest.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index 408f68e35418..216ae984c67a 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -3888,7 +3888,7 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
 
   if (Right.is(tok::kw___attribute) ||
       (Right.is(tok::l_square) && Right.is(TT_AttributeSquare)))
-    return true;
+    return !Left.is(TT_AttributeSquare);
 
   if (Left.is(tok::identifier) && Right.is(tok::string_literal))
     return true;

diff  --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 86eeb2705595..9a654d66250c 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -7672,6 +7672,19 @@ TEST_F(FormatTest, UnderstandsSquareAttributes) {
                MultiLineFunctions);
 }
 
+TEST_F(FormatTest, AttributePenaltyBreaking) {
+  FormatStyle Style = getLLVMStyle();
+  verifyFormat("void ABCDEFGH::ABCDEFGHIJKLMN(\n"
+               "    [[maybe_unused]] const shared_ptr<ALongTypeName> &C d) {}",
+               Style);
+  verifyFormat("void ABCDEFGH::ABCDEFGHIJK(\n"
+               "    [[maybe_unused]] const shared_ptr<ALongTypeName> &C d) {}",
+               Style);
+  verifyFormat("void ABCDEFGH::ABCDEFGH([[maybe_unused]] const "
+               "shared_ptr<ALongTypeName> &C d) {\n}",
+               Style);
+}
+
 TEST_F(FormatTest, UnderstandsEllipsis) {
   verifyFormat("int printf(const char *fmt, ...);");
   verifyFormat("template <class... Ts> void Foo(Ts... ts) { Foo(ts...); }");