Function parse_function_decl

language/move-compiler/src/parser/syntax.rs:1785–1890

Parse a function declaration: FunctionDecl = "fun" "(" Comma ")" (":" )? ("acquires" ("," )*)? ("{" "}" | ";")

(
    attributes: Vec<Attributes>,
    start_loc: usize,
    modifiers: Modifiers,
    context: &mut Context,
)

//          ("{" <Sequence> "}" | ";")
//
fn parse_function_decl(
    attributes: Vec<Attributes>,
    start_loc: usize,
    modifiers: Modifiers,
    context: &mut Context,
) -> Result<Function, Diagnostic> {
    let Modifiers {
        visibility,
        mut entry,
        native,
    } = modifiers;

    if let Some(Visibility::Script(vloc)) = visibility {
        let msg = format!(
            "'{script}' is deprecated in favor of the '{entry}' modifier. \
            Replace with '{public} {entry}'",
            script = Visibility::SCRIPT,
            public = Visibility::PUBLIC,
            entry = ENTRY_MODIFIER,
        );
        context
            .env
            .add_diag(diag!(Uncategorized::DeprecatedWillBeRemoved, (vloc, msg,)));
        if entry.is_none() {
            entry = Some(vloc)
        }
    }

    // "fun" <FunctionDefName>
    consume_token(context.tokens, Tok::Fun)?;
    let name = FunctionName(parse_identifier(context)?);
    let type_parameters = parse_optional_type_parameters(context)?;

    // "(" Comma<Parameter> ")"
    let parameters = parse_comma_list(
        context,
        Tok::LParen,
        Tok::RParen,
        parse_parameter,
        "a function parameter",
    )?;

    // (":" <Type>)?
    let return_type = if match_token(context.tokens, Tok::Colon)? {
        parse_type(context)?
    } else {
        sp(name.loc(), Type_::Unit)
    };

    // ("acquires" (<NameAccessChain> ",")* <NameAccessChain> ","?
    let mut acquires = vec![];
    if match_token(context.tokens, Tok::Acquires)? {
        let follows_acquire = |tok| matches!(tok, Tok::Semicolon | Tok::LBrace);
        loop {
            acquires.push(parse_name_access_chain(context, || {
                "a resource struct name"
            })?);
            if follows_acquire(context.tokens.peek()) {