[clang-format] Fix breaking of qualified operator

Summary:
From https://bugs.llvm.org/show_bug.cgi?id=40516
```
$ cat a.cpp
const NamespaceName::VeryLongClassName &NamespaceName::VeryLongClassName::myFunction() {
  // do stuff
}

const NamespaceName::VeryLongClassName &NamespaceName::VeryLongClassName::operator++() {
  // do stuff
}
$ ~/ll/build/opt/bin/clang-format -style=LLVM a.cpp
const NamespaceName::VeryLongClassName &
NamespaceName::VeryLongClassName::myFunction() {
  // do stuff
}

const NamespaceName::VeryLongClassName &NamespaceName::VeryLongClassName::
operator++() {
  // do stuff
}
```
What was happening is that the split penalty before `operator` was being set to
a smaller value by a prior if block. Moved checks around to fix this and added a
regression test.

Reviewers: djasper

Reviewed By: djasper

Tags: #clang

Differential Revision: https://reviews.llvm.org/D57604

llvm-svn: 353033

1 files changed, 12 insertions, 0 deletions

diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 99b2beadc4a..2b0ef9a9dd5 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -4183,6 +4183,18 @@ TEST_F(FormatTest, BreaksFunctionDeclarations) {
                Style);
 }
 
+TEST_F(FormatTest, DontBreakBeforeQualifiedOperator) {
+  // Regression test for https://bugs.llvm.org/show_bug.cgi?id=40516:
+  // Prefer keeping `::` followed by `operator` together.
+  EXPECT_EQ("const aaaa::bbbbbbb &\n"
+            "ccccccccc::operator++() {\n"
+            "  stuff();\n"
+            "}",
+            format("const aaaa::bbbbbbb\n"
+                   "&ccccccccc::operator++() { stuff(); }",
+                   getLLVMStyleWithColumns(40)));
+}
+
 TEST_F(FormatTest, TrailingReturnType) {
   verifyFormat("auto foo() -> int;\n");
   verifyFormat("struct S {\n"