features.md

Features and Configuration

This document describes the feature flags and configuration options available in diagnostics_tools.

Default Features

By default, the crate enables these features:

[dependencies]
diagnostics_tools = "0.11"  # Includes: enabled, runtime, compiletime, memory_layout

This gives you access to all assertion types:

• Runtime assertions (a_* macros)
• Compile-time assertions (cta_* macros)
• Memory layout validation (cta_type_*, cta_ptr_*, cta_mem_*)

Available Feature Flags

Core Features

enabled (default)

Master switch that enables the crate functionality. Without this, all macros become no-ops.

[dependencies]
diagnostics_tools = { version = "0.11", features = ["enabled"] }

full

Enables all features - equivalent to enabling all individual feature flags.

[dependencies]
diagnostics_tools = { version = "0.11", features = ["full"] }

Functionality Features

diagnostics_runtime_assertions (default)

Enables runtime assertion macros:

• a_true!, a_false!
• a_id!, a_not_id!
• a_dbg_true!, a_dbg_false!, a_dbg_id!, a_dbg_not_id!

[dependencies]
diagnostics_tools = { version = "0.11", features = ["enabled", "diagnostics_runtime_assertions"] }

diagnostics_compiletime_assertions (default)

Enables compile-time assertion macros:

• cta_true!

[dependencies]
diagnostics_tools = { version = "0.11", features = ["enabled", "diagnostics_compiletime_assertions"] }

diagnostics_memory_layout (default)

Enables memory layout validation macros:

• cta_type_same_size!, cta_type_same_align!
• cta_ptr_same_size!, cta_mem_same_size!

[dependencies]
diagnostics_tools = { version = "0.11", features = ["enabled", "diagnostics_memory_layout"] }

Environment Features

no_std

Enables no_std support for embedded and constrained environments.

[dependencies]
diagnostics_tools = { version = "0.11", features = ["no_std", "enabled"] }

When no_std is enabled:

• Runtime assertions still work but with limited formatting
• Compile-time assertions work exactly the same
• Memory layout validation works exactly the same

use_alloc

When using no_std, you can still enable heap allocation with use_alloc.

[dependencies]  
diagnostics_tools = { version = "0.11", features = ["no_std", "use_alloc", "enabled"] }

Custom Feature Combinations

Minimal Runtime Only

For projects that only need runtime assertions:

[dependencies]
diagnostics_tools = { 
    version = "0.11", 
    default-features = false, 
    features = ["enabled", "diagnostics_runtime_assertions"] 
}

Compile-Time Only

For projects that only need compile-time validation:

[dependencies]
diagnostics_tools = { 
    version = "0.11", 
    default-features = false, 
    features = ["enabled", "diagnostics_compiletime_assertions"] 
}

Memory Layout Only

For low-level code that only needs memory validation:

[dependencies]
diagnostics_tools = { 
    version = "0.11", 
    default-features = false, 
    features = ["enabled", "diagnostics_memory_layout"] 
}

Embedded/No-Std

For embedded projects:

[dependencies]
diagnostics_tools = { 
    version = "0.11", 
    default-features = false, 
    features = ["no_std", "enabled", "diagnostics_compiletime_assertions", "diagnostics_memory_layout"] 
}

Conditional Compilation

You can conditionally enable features based on your build configuration:

[dependencies]
diagnostics_tools = { version = "0.11", default-features = false, features = ["enabled"] }

[dependencies.diagnostics_tools.features]
# Only include runtime assertions in debug builds
diagnostics_runtime_assertions = { optional = true }

[features]
default = []
debug_asserts = ["diagnostics_tools/diagnostics_runtime_assertions"]

Then use with:

# Development build with runtime assertions
cargo build --features debug_asserts

# Release build without runtime assertions  
cargo build --release

Performance Impact

Feature Impact on Binary Size

Feature	Binary Size Impact	Runtime Impact
diagnostics_runtime_assertions	Medium (includes pretty_assertions)	Same as standard assertions
diagnostics_compiletime_assertions	None (compile-time only)	None
diagnostics_memory_layout	None (compile-time only)	None
no_std	Reduces size	Slightly reduced formatting

Recommendation by Use Case

Testing/Development:

diagnostics_tools = "0.11"  # Use all default features

Production Libraries:

diagnostics_tools = { 
    version = "0.11", 
    default-features = false, 
    features = ["enabled", "diagnostics_compiletime_assertions", "diagnostics_memory_layout"] 
}

Embedded Systems:

diagnostics_tools = { 
    version = "0.11", 
    default-features = false, 
    features = ["no_std", "enabled", "diagnostics_compiletime_assertions"] 
}

High-Performance Applications:

# Development
[dependencies.diagnostics_tools]
version = "0.11"

# Production (disable runtime assertions)
[dependencies.diagnostics_tools]  
version = "0.11"
default-features = false
features = ["enabled", "diagnostics_compiletime_assertions", "diagnostics_memory_layout"]

Feature Interaction

Some features have dependencies on each other:

• enabled is required for any functionality
• use_alloc requires no_std
• All diagnostic features require enabled

The crate will give compile-time errors if incompatible features are selected.