[clang-format] Weird line breaks with AlignAfterOpenBracket: BlockIndent

[lukasberbuer]

Following example showcases weird line-breaking choices with AlignAfterOpenBracket: BlockIndent:

• Pure LLVM style:

  auto result = std::optional<int>(123)
                  .transform([](int n) { return n + 100; })
                  .transform([](int n) {
                      // multiline lambda
                      return std::to_string(n);
                  });

• With AlignAfterOpenBracket: BlockIndent 💥:

  auto result = std::optional<int>(123).transform([](int n) { return n + 100; }
  ).transform([](int n) {
      // multiline lambda
      return std::to_string(n);
  });

• Desired output:

  auto result = std::optional<int>(123)
      .transform([](int n) { return n + 100; })
      .transform([](int n) {
          // multiline lambda
          return std::to_string(n);
      });

Any ideas how to fix this? Can it be done just via the config?

.clang-format

---
BasedOnStyle: LLVM
AlignAfterOpenBracket: BlockIndent
AlignOperands: DontAlign

[llvmbot]

@llvm/issue-subscribers-bug

Author: Lukas Berbuer (lukasberbuer)

Following example showcases weird line-breaking choices with `AlignAfterOpenBracket: BlockIndent`:

• Pure LLVM style:

  auto result = std::optional<int>(123)
                  .transform([](int n) { return n + 100; })
                  .transform([](int n) {
                      // multiline lambda
                      return std::to_string(n);
                  });

• With AlignAfterOpenBracket: BlockIndent 💥:

  auto result = std::optional<int>(123).transform([](int n) { return n + 100; }
  ).transform([](int n) {
      // multiline lambda
      return std::to_string(n);
  });

• Desired output:

  auto result = std::optional<int>(123)
      .transform([](int n) { return n + 100; })
      .transform([](int n) {
          // multiline lambda
          return std::to_string(n);
      });

Any ideas how to fix this? Can it be done just via the config?

.clang-format

---
BasedOnStyle: LLVM
AlignAfterOpenBracket: BlockIndent
AlignOperands: DontAlign

[gedare]

You can achieve this with the style option from #118409 to reduce the penalty for breaking before the member access, and the fix (pending) from #124998 to avoid breaking the right parens of 123).

You need to set a penalty much lower than the default. 30 seemed to do the trick:

$ cat 103306.c 
auto result = std::optional<int>(123)
                .transform([](int n) { return n + 100; })
                .transform([](int n) {
                    // multiline lambda
                    return std::to_string(n);
                });

$ clang-format --style="{BasedOnStyle: llvm, AlignAfterOpenBracket: BlockIndent, PenaltyBreakBeforeMemberAccess: 30}" 103306.c
auto result = std::optional<int>(123)
                  .transform([](int n) { return n + 100; })
                  .transform([](int n) {
                    // multiline lambda
                    return std::to_string(n);
                  });

[lukasberbuer]

Thanks @gedare, this solves most of this formatting issue.
Is there any way to control the indentation of member access after a line break?

- auto result = std::optional<int>(123)
-                 .transform([](int n) { return n + 100; });
+ auto result = std::optional<int>(123)
+     .transform([](int n) { return n + 100; });

[gedare]

Thanks @gedare, this solves most of this formatting issue. Is there any way to control the indentation of member access after a line break?

• auto result = std::optional(123)

•             .transform([](int n) { return n + 100; });
  

• auto result = std::optional(123)

• .transform([](int n) { return n + 100; });
  

The BlockIndent option uses the ContinuationIndent. I think this might interact withAlignOperands