clang-format generates extra trailing spaces in the last line with InsertNewlineAtEOF enabled

[kevinptt0323]

clang-format generates extra trailing spaces in the last line when the following three statements are true:

1. InsertNewlineAtEOF is true.
2. The file does not end with EOL (0x0a)
3. The argument -lines is specified

Minimal reproducible example:

$ clang-format --version
Ubuntu clang-format version 18.1.3 (1ubuntu1)
$ cat test.cpp
namespace foo {
int bar;
} // namespace foo$ xxd test.cpp
00000000: 6e61 6d65 7370 6163 6520 666f 6f20 7b0a  namespace foo {.
00000010: 696e 7420 6261 723b 0a7d 202f 2f20 6e61  int bar;.} // na
00000020: 6d65 7370 6163 6520 666f 6f              mespace foo
$ clang-format -style '{InsertNewlineAtEOF: true}' test.cpp -lines 1:3 | xxd
00000000: 6e61 6d65 7370 6163 6520 666f 6f20 7b0a  namespace foo {.
00000010: 696e 7420 6261 723b 0a7d 202f 2f20 6e61  int bar;.} // na
00000020: 6d65 7370 6163 6520 666f 6f0a 2020 2020  mespace foo.    
00000030: 2020 2020 2020 2020 2020 2020 2020                     
$ clang-format -style '{InsertNewlineAtEOF: true}' test.cpp | xxd
00000000: 6e61 6d65 7370 6163 6520 666f 6f20 7b0a  namespace foo {.
00000010: 696e 7420 6261 723b 0a7d 202f 2f20 6e61  int bar;.} // na
00000020: 6d65 7370 6163 6520 666f 6f0a            mespace foo.
$ clang-format -style '{InsertNewlineAtEOF: false}' test.cpp -lines 1:3 | xxd
00000000: 6e61 6d65 7370 6163 6520 666f 6f20 7b0a  namespace foo {.
00000010: 696e 7420 6261 723b 0a7d 202f 2f20 6e61  int bar;.} // na
00000020: 6d65 7370 6163 6520 666f 6f              mespace foo

[owenca]

How did you run clang-format?

[kevinptt0323]

How did you run clang-format?

Like google/vim-codefmt#217 mentioned, I use https://github.com/google/vim-codefmt with Vim to format the code. The plugin passes the buffer content to clang-format and replace the whole buffer.

I've narrowed down the issue to the minimal reproducible example in #108333 (comment). The key point is that the last line does not contain EOL (0x0a), which causes the bug.

Another one-line example:

$ echo -n $'namespace {\nint a;\n} // namespace' | clang-format -style '{InsertNewlineAtEOF: true}' -lines 1:3 | xxd
00000000: 6e61 6d65 7370 6163 6520 7b0a 696e 7420  namespace {.int
00000010: 613b 0a7d 202f 2f20 6e61 6d65 7370 6163  a;.} // namespac
00000020: 650a 2020 2020 2020 2020 2020 2020 2020  e.

[llvmbot]

@llvm/issue-subscribers-bug

Author: Kevin Lin (kevinptt0323)

clang-format generates extra trailing spaces in the last line when the following three statements are true:

1. InsertNewlineAtEOF is true.
2. The file does not end with EOL (0x0a)
3. The argument -lines is specified

Minimal reproducible example:

$ clang-format --version
Ubuntu clang-format version 18.1.3 (1ubuntu1)
$ cat test.cpp
namespace foo {
int bar;
} // namespace foo$ xxd test.cpp
00000000: 6e61 6d65 7370 6163 6520 666f 6f20 7b0a  namespace foo {.
00000010: 696e 7420 6261 723b 0a7d 202f 2f20 6e61  int bar;.} // na
00000020: 6d65 7370 6163 6520 666f 6f              mespace foo
$ clang-format -style '{InsertNewlineAtEOF: true}' test.cpp -lines 1:3 | xxd
00000000: 6e61 6d65 7370 6163 6520 666f 6f20 7b0a  namespace foo {.
00000010: 696e 7420 6261 723b 0a7d 202f 2f20 6e61  int bar;.} // na
00000020: 6d65 7370 6163 6520 666f 6f0a 2020 2020  mespace foo.    
00000030: 2020 2020 2020 2020 2020 2020 2020                     
$ clang-format -style '{InsertNewlineAtEOF: true}' test.cpp | xxd
00000000: 6e61 6d65 7370 6163 6520 666f 6f20 7b0a  namespace foo {.
00000010: 696e 7420 6261 723b 0a7d 202f 2f20 6e61  int bar;.} // na
00000020: 6d65 7370 6163 6520 666f 6f0a            mespace foo.
$ clang-format -style '{InsertNewlineAtEOF: false}' test.cpp -lines 1:3 | xxd
00000000: 6e61 6d65 7370 6163 6520 666f 6f20 7b0a  namespace foo {.
00000010: 696e 7420 6261 723b 0a7d 202f 2f20 6e61  int bar;.} // na
00000020: 6d65 7370 6163 6520 666f 6f              mespace foo

[owenca]

/cherry-pick 7153a4b

[llvmbot]

/pull-request #109170