Struct Deps 

pub struct Deps {
    pub emit: bool,
    pub instead_of_compiling: bool,
    pub system_headers: bool,
    pub file: Option<String>,
    pub targets: Vec<String>,
    pub phony: bool,
}

What the -M family asks for, which is a make rule saying what a source file was built from.

Design: spec/04-driver-and-cli.md section 4.4.

This is a compiler flag rather than a separate tool because the answer is the set of files the preprocessor opened, and nothing outside the preprocessor knows what that was. A build system that generates its own makefiles asks for it on every compilation, which is why section 4.4 calls the family required rather than convenient.

Fields

emit: bool

Whether a rule is produced at all, which is any of -M, -MM, -MD and -MMD.

instead_of_compiling: bool

Whether the rule is produced instead of compiling, which is -M and -MM and not the two that end in D.

The split is GCC’s and it is about who reads the answer. The two that stop after the rule write it to standard output for a person, and the two that do not write it to a file beside the object for make to include on the next run.

system_headers: bool

Whether a header found in a system directory is listed, which -MM and -MMD turn off.

A build that lists them is a build that rebuilds the world when the C library is updated, which is either what somebody wanted or the reason they reached for the other spelling.

On unless a flag turned it off, and nothing turns it back on. That is GCC’s behaviour and not an oversight: -MM -M leaves the system headers out, because the flag that asks for fewer of them is read as the answer to a question the other one never asked.

file: Option<String>

Where the rule is written, from -MF, with - meaning standard output.

None is the default, which is standard output when the rule replaces the compilation and the output file with a .d suffix when it does not.

targets: Vec<String>

What the rule’s targets are, from -MT and -MQ, in the order they were given.

Already escaped, because that is the whole of the difference between the two flags: -MQ escapes what it is given and -MT writes it through untouched. Empty means the target is worked out from the output file, which is what a build that passes neither expects.

phony: bool

Whether every prerequisite except the source gets a target of its own with no recipe, from -MP.

This is what stops make failing outright when a header is deleted. Without it the old rule names a file that is gone and no rule makes it, and the build stops on a header that nothing needs any more.

Trait Implementations

impl Clone for Deps

fn clone(&self) -> Deps

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Deps

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Deps

fn default() -> Deps

Returns the “default value” for a type.

impl Eq for Deps

impl PartialEq for Deps

fn eq(&self, other: &Deps) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Deps