get-breaking-diff.ps1

# Runn th2se 2 commands:
# 1. Generate FULL diff:
#    git diff OLD_BRANCH NEW_BRANCH  --output=complete.diff **\PublicAPI.*.txt
# 2. Generate REDUCE diff:
#    .\eng\scripts\get-breaking-diff.ps1 -Source .\complete.diff -Out .\breaks.diff -Unique .\unique.diff

[CmdletBinding(PositionalBinding=$false)]
param ($Source, $Out, $Unique)

Set-StrictMode -version 2.0
$ErrorActionPreference = "Stop"

$content = Get-Content $Source

$breaking = @()
$lastItem = $null

for ($i = 0; $i -lt $content.Count; $i++) {
    $item = $content[$i]

    # remove -IntPtr +nint diffs
    if ($item.Contains('IntPtr')) {
        $foundNint = $false
        foreach ($c in $content) {
            if ($c.Substring(1) -eq $item.Substring(1).Replace('System.IntPtr', 'nint')) {
                $foundNint = $c
                break
            }
        }
        if ($foundNint) {
            Write-Host "Removed because nint/IntPtr"
            Write-Host "        $item"
            Write-Host "        $foundNint"
            continue
        }
    }

    # remove (object parameter) (object? parameter) diffs
    if ($item.Contains('(object parameter)')) {
        $foundNull = $false
        foreach ($c in $content) {
            if ("~" + $c.Substring(1) -eq $item.Substring(1).Replace('(object parameter)', '(object? parameter)')) {
                $foundNull = $c
                break
            }
        }
        if ($foundNull) {
            Write-Host "Removed because (object[?] parameter)"
            Write-Host "        $item"
            Write-Host "        $foundNull"
            continue
        }
    }

    # remove nullability diffs
    $itemWithoutNull = $item.Substring(1).Replace('?', '_').Replace('!', '_')
    if ($itemWithoutNull -ne $item.Substring(1)) {
        $wasNullChange = $false
        for ($j = 0; $j -lt $breaking.Count; $j++) {
            $b = $breaking[$j]
            # skip null or equal items
            if (($null -eq $b) -or ($item -eq $b)) { continue }
            $bWithoutNull = $b.Substring(1).Replace('?', '_').Replace('!', '_')
            if ($bWithoutNull -eq $itemWithoutNull) {
                $breaking[$j] = $null
                $wasNullChange = $true
                break
            }
        }
        if ($wasNullChange) {
            Write-Host "Removed because #nullability"
            Write-Host "        $item"
            Write-Host "        $b"
            continue
        }
    }

    # remove empty lines
    if ($item -eq '-') { continue }
    # remove non-important items
    if (-not $item.StartsWith('-') -and -not $item.StartsWith('diff')) { continue }
    # remove ending items
    if ($item.StartsWith('---')) { continue }
    # remove overrides as this is not breaking
    if ($item.StartsWith('-~override') -or $item.StartsWith('-override')) { continue }
    # remove last item if it was an empty group
    if ($lastItem -and $lastItem.StartsWith('diff') -and $item.StartsWith('diff')) {
        $breaking[$breaking.Length - 1] = $null
    }

    # remove ctor(X? x = null) when there is ctor(X?) AND ctor()
    $potentialMatch = '(Microsoft.Maui.IPropertyMapper? mapper = null)'
    $noNullMatch = '(Microsoft.Maui.IPropertyMapper? mapper)'
    $noArgsMatch = '()'
    if ($item.Contains($potentialMatch)) {
        $foundNoNull = $false
        $foundNoArgs = $false
        foreach ($c in $content) {
            if ((-not $foundNoNull) -and ($c.Substring(1) -eq $item.Substring(1).Replace($potentialMatch, $noNullMatch))) {
                $foundNoNull = $c
            } elseif ((-not $foundNoArgs) -and ($c.Substring(1) -eq $item.Substring(1).Replace($potentialMatch, $noArgsMatch))) {
                $foundNoArgs = $c
            }
            if ($foundNoNull -and $foundNoArgs) {
                break
            }
        }
        if ($foundNoNull -and $foundNoArgs) {
            Write-Host "Removed because default nulls"
            Write-Host "        $item"
            Write-Host "        $foundNoNull"
            Write-Host "        $foundNoArgs"
            continue
        }
    }

    # remove same as above, but different
    $potentialMatch = '(Microsoft.Maui.IPropertyMapper! mapper, Microsoft.Maui.CommandMapper? commandMapper = null)'
    $noNullMatch = '(Microsoft.Maui.IPropertyMapper? mapper, Microsoft.Maui.CommandMapper? commandMapper)'
    $noArgsMatch = '(Microsoft.Maui.IPropertyMapper? mapper)'
    if ($item.Contains($potentialMatch)) {
        $foundNoNull = $false
        $foundNoArgs = $false
        foreach ($c in $content) {
            if ((-not $foundNoNull) -and ($c.Substring(1) -eq $item.Substring(1).Replace($potentialMatch, $noNullMatch))) {
                $foundNoNull = $c
            } elseif ((-not $foundNoArgs) -and ($c.Substring(1) -eq $item.Substring(1).Replace($potentialMatch, $noArgsMatch))) {
                $foundNoArgs = $c
            }
            if ($foundNoNull -and $foundNoArgs) {
                break
            }
        }
        if ($foundNoNull -and $foundNoArgs) {
            Write-Host "Removed because default nulls 2.0"
            Write-Host "        $item"
            Write-Host "        $foundNoNull"
            Write-Host "        $foundNoArgs"
            continue
        }
    }

    # remove same as above, but different
    $potentialMatch = '(Microsoft.Maui.IPropertyMapper? mapper = null, Microsoft.Maui.CommandMapper? commandMapper = null)'
    $noNullMatch = '(Microsoft.Maui.IPropertyMapper? mapper, Microsoft.Maui.CommandMapper? commandMapper)'
    $noArgsMatch = '()'
    if ($item.Contains($potentialMatch)) {
        $foundNoNull = $false
        $foundNoArgs = $false
        foreach ($c in $content) {
            if ((-not $foundNoNull) -and ($c.Substring(1) -eq $item.Substring(1).Replace($potentialMatch, $noNullMatch))) {
                $foundNoNull = $c
            } elseif ((-not $foundNoArgs) -and ($c.Substring(1) -eq $item.Substring(1).Replace($potentialMatch, $noArgsMatch))) {
                $foundNoArgs = $c
            }
            if ($foundNoNull -and $foundNoArgs) {
                break
            }
        }
        if ($foundNoNull -and $foundNoArgs) {
            Write-Host "Removed because default nulls 3.0"
            Write-Host "        $item"
            Write-Host "        $foundNoNull"
            Write-Host "        $foundNoArgs"
            continue
        }
    }

    # remove ~Xxx when Xxx exists still
    if ($item.StartsWith('-~')) {
        $foundNullRemove = $null
        foreach ($c in $content) {
            if (($c.Substring(1) -eq $item.Substring(2)) -or
                ($c.Substring(1) -eq ($item.Substring(2) + '?')) -or
                ($c.Substring(1) -eq ($item.Substring(2) + '!'))) {
                $foundNullRemove = $c
                break
            }
        }
        if ($foundNullRemove) {
            Write-Host "Removed because nullability was enabled"
            Write-Host "        $item"
            Write-Host "        $foundNullRemove"
            continue
        }
    }

    $breaking += $item
    $lastItem = $item
}

# remove last empty group
if ($lastItem -and $breaking[$breaking.Length - 1].StartsWith('diff')) {
    $breaking[$breaking.Length - 1] = $null
}

$breaking |
    Where-Object { $null -ne $_ } |
    Set-Content $Out

$breaking |
    Where-Object { ($null -ne $_) -and (-not $_.StartsWith('diff')) } |
    Sort-Object -Unique |
    Set-Content $Unique