Configuration

mir can be configured through CLI flags and an optional XML config file (mir.xml). There is no required config file — mir works out of the box with sensible defaults.

Config file (mir.xml)

When run, mir searches upward from the current directory for mir.xml. If no mir.xml is found, it falls back to psalm.xml (Psalm compatibility). You can also point to a config file explicitly with -c.

Example mir.xml

<?xml version="1.0"?>
<mir xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" errorLevel="3">
  <projectFiles>
    <directory name="src" />
    <directory name="lib" />
  </projectFiles>

  <ignoreFiles>
    <directory name="vendor" />
  </ignoreFiles>

  <issueHandlers>
    <UndefinedVariable errorLevel="suppress" />
    <PossiblyNullReference errorLevel="warning" />
  </issueHandlers>

  <phpVersion>8.2</phpVersion>
  <findUnusedCode>true</findUnusedCode>
  <findUnusedVariables>true</findUnusedVariables>
</mir>

Config file fields

Field	Description
errorLevel attribute	Global strictness: 1 (errors only) to 8 (lenient). Default: 2.
<projectFiles>	Source directories to analyze.
<ignoreFiles>	Directories or files to exclude (e.g. vendor/).
<issueHandlers>	Per-issue-kind severity overrides (see below).
<phpVersion>	Target PHP version string, e.g. 8.2.
<findUnusedCode>	Enable dead-code detection (true/false). Default: false.
<findUnusedVariables>	Enable unused-variable checking (true/false). Default: false.

Issue handlers

Each child element of <issueHandlers> is an issue kind name with an errorLevel attribute:

Level	Effect
error	Treat as error (exit code 1)
warning	Treat as warning
info	Treat as info (only shown with --show-info or errorLevel >= 7)
suppress	Silence the issue entirely

<issueHandlers>
  <UndefinedMethod errorLevel="suppress" />
  <InvalidArgument errorLevel="warning" />
</issueHandlers>

CLI flags

CLI flags always override values from the config file.

Flag	Default	Description
-c, --config <FILE>	auto	Config file path. Auto-discovers mir.xml / psalm.xml if omitted.
--baseline <FILE>	auto	Suppress known issues from a baseline XML. Auto-discovers psalm-baseline.xml.
--set-baseline [FILE]	psalm-baseline.xml	Write all current issues to a baseline file and exit.
--update-baseline	off	Remove resolved issues from the baseline.
--ignore-baseline	off	Report all issues, ignoring the baseline.
--error-level <1-8>	from config	Override global error level.
--php-version <X.Y>	from config	Target PHP version (e.g. 8.2).
--format <FORMAT>	text	Output format: text, json, github, junit, sarif.
--show-info	off	Include info-level issues (redundancies, style).
-j, --threads <N>	CPU count	Parallelism.
--cache-dir <DIR>	off	Enable incremental cache in DIR.
--stats	off	Print file count, error/warning totals, elapsed time.
-v, --verbose	off	Print per-file issue counts.
-q, --quiet	off	Suppress all output; use exit code only.
--no-progress	off	Disable the progress bar.

Baselines

A baseline file records known issues so that they are suppressed on future runs. This lets you adopt mir incrementally — silence pre-existing issues and focus on new ones as they are introduced.

Baseline files use Psalm’s XML format, so an existing psalm-baseline.xml works directly.

Baseline workflow

# 1. Generate a baseline from the current issues (first adoption)
mir --set-baseline psalm-baseline.xml src/

# 2. Subsequent runs suppress baselined issues automatically
#    (psalm-baseline.xml in the cwd is picked up automatically)
mir src/

# 3. Explicitly point to a baseline in a non-standard location
mir --baseline path/to/my-baseline.xml src/

# 4. After fixing issues, shrink the baseline (removes resolved entries)
mir --update-baseline src/

# 5. Temporarily ignore the baseline to see all issues
mir --ignore-baseline src/

Common configurations

Basic project with vendor exclusion

<?xml version="1.0"?>
<mir errorLevel="3">
  <projectFiles>
    <directory name="src" />
  </projectFiles>
  <ignoreFiles>
    <directory name="vendor" />
  </ignoreFiles>
</mir>

CI pipeline (GitHub Actions)

# In .github/workflows/mir.yml:
mir --format github --no-progress --baseline psalm-baseline.xml src/

Strict analysis (errors only, no warnings)

mir --error-level 1 src/

Target a specific PHP version

mir --php-version 8.1 src/

Suppress a noisy issue kind project-wide

<issueHandlers>
  <UndefinedMethod errorLevel="suppress" />
</issueHandlers>

Incremental analysis with caching

mir --cache-dir .mir-cache src/