Diktat produces wrong line:column numbers in the "fix" mode if multiple rules are applied

[0x6675636b796f75676974687562]

Diktat 1.2.3, Ktlint 0.46.1.
Consider this code fragment:

@file:Suppress(
    "MISSING_KDOC_TOP_LEVEL",
    "MISSING_KDOC_CLASS_ELEMENTS",
    "EMPTY_BLOCK_STRUCTURE_ERROR",
)

package org.cqfn.diktat

class                                        Example{fun memberFunction(){}}

Diktat (e.g. when run from the command line) reports the following errors, all on the same line:

$ diktat --relative Example.kt
Example.kt:9:6: [TOO_MANY_CONSECUTIVE_SPACES] too many consecutive spaces: found: 40. need to be: 1 (diktat-ruleset:too-many-spaces)
Example.kt:9:53: [WRONG_WHITESPACE] incorrect usage of whitespaces for code separation: there should be a whitespace before '{' (diktat-ruleset:horizontal-whitespace)
Example.kt:9:54: [BRACES_BLOCK_STRUCTURE_ERROR] braces should follow 1TBS style: incorrect same line after opening brace (diktat-ruleset:block-structure)
Example.kt:9:54: [MISSING_KDOC_ON_FUNCTION] all public, internal and protected functions should have Kdoc with proper tags: memberFunction (cannot be auto-corrected) (diktat-ruleset:kdoc-methods)
Example.kt:9:74: [WRONG_WHITESPACE] incorrect usage of whitespaces for code separation: there should be a whitespace before '{' (diktat-ruleset:horizontal-whitespace)
Example.kt:9:76: [BRACES_BLOCK_STRUCTURE_ERROR] braces should follow 1TBS style: no newline before closing brace (diktat-ruleset:block-structure)

Now, when run in the "fix" mode, Diktat will correct all of the above errors except for the MISSING_KDOC_ON_FUNCTION:

$ diktat --relative -F Example.kt
Example.kt:9:21: [MISSING_KDOC_ON_FUNCTION] all public, internal and protected functions should have Kdoc with proper tags: memberFunction (cannot be auto-corrected) (diktat-ruleset:kdoc-methods)

As you can see, the line:column numbers will no longer be 9:54 but 9:21, because some of the rules have been already applied and some of the errors fixed. Yet, 9:21 is absolutely misleading, because the resulting (formatted) file will look like this:

@file:Suppress(
    "MISSING_KDOC_TOP_LEVEL",
    "MISSING_KDOC_CLASS_ELEMENTS",
    "EMPTY_BLOCK_STRUCTURE_ERROR",
)

package org.cqfn.diktat

class Example {
    fun memberFunction() {}
}

If we run Diktat again (now against the reformatted file), there will be 10:5 instead of 9:21:

$ diktat --relative Example.kt
Example.kt:10:5: [MISSING_KDOC_ON_FUNCTION] all public, internal and protected functions should have Kdoc with proper tags: memberFunction (cannot be auto-corrected) (diktat-ruleset:kdoc-methods)

The problem becomes even more evident after the upgrade to Ktlint 0.47.x (API Changes & RuleSet providers), because it has changed the way AST elements are traversed.

Consider there're multiple rules, ordered in a specific way:

graph LR;
    A-->B;
    B-->C;

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Assuming there're multiple AST syntax nodes enclosed in each other:

graph TD;
    File-->Node;
    Node-->Leaf;

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Ktlint 0.46 used to recursively apply the above rules in the following order:

flowchart TB;
  subgraph File
    direction LR;
    A1["A"]-->B1["B"];
    B1["B"]-->C1["C"];
  end
  subgraph Node
    direction LR;
    A2["A"]-->B2["B"];
    B2["B"]-->C2["C"];
  end
  subgraph Leaf
    direction LR;
    A3["A"]-->B3["B"];
    B3["B"]-->C3["C"];
  end
    File-->Node;
    Node-->Leaf;

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As of Ktlint 0.47, the traversal order is different:

flowchart TB;
  subgraph A
    direction LR;
    File1["File"]-->Node1["Node"]
    Node1["Node"]-->Leaf1["Leaf"]
  end
  subgraph B
    direction LR;
    File2["File"]-->Node2["Node"]
    Node2["Node"]-->Leaf2["Leaf"]
  end
  subgraph C
    direction LR;
    File3["File"]-->Node3["Node"]
    Node3["Node"]-->Leaf3["Leaf"]
  end
    A-->B;
    B-->C;

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In practice, when Diktat is run in the "fix" mode, this change in Ktlint behaviour results in the same error (e.g.: MISSING_KDOC_ON_FUNCTION) reported multiple times against different (incorrect) locations within a file.

Probably, we should change our strategy to first running KtLint.format() ignoring any errors followed by KtLint.lint(), and only report errors produced by the last lint() call.

In particular, this blocks saveourtool/benedikt#3.

[0x6675636b796f75676974687562]

@akuleshov7, @nulls, WDYT?

[nulls]

@0x6675636b796f75676974687562, agree. We need to split fix and warn parts: we need to fix everything that possible in first run and then warn about left errors.

But suggestion to make this change with old version of ktlint in first phase: I think it should work for the old version too