garando_syntax2 0.1.0

use crate::ast;
use crate::attr::HasAttrs;
use crate::codemap::Spanned;
use crate::feature_gate::{
    feature_err, get_features, Features, GateIssue, EXPLAIN_STMT_ATTR_SYNTAX,
};
use crate::parse::{token, ParseSess};
use crate::syntax_pos::Span;
use crate::{attr, fold};

use crate::ptr::P;
use crate::util::small_vector::SmallVector;

/// A folder that strips out items that do not belong in the current configuration.
pub struct StripUnconfigured<'a> {
    pub should_test: bool,
    pub sess: &'a ParseSess,
    pub features: Option<&'a Features>,
}

// `cfg_attr`-process the crate's attributes and compute the crate's features.
pub fn features(
    mut krate: ast::Crate,
    sess: &ParseSess,
    should_test: bool,
) -> (ast::Crate, Features) {
    let features;
    {
        let mut strip_unconfigured = StripUnconfigured {
            should_test: should_test,
            sess: sess,
            features: None,
        };

        let unconfigured_attrs = krate.attrs.clone();
        let err_count = sess.span_diagnostic.err_count();
        if let Some(attrs) = strip_unconfigured.configure(krate.attrs) {
            krate.attrs = attrs;
        } else {
            // the entire crate is unconfigured
            krate.attrs = Vec::new();
            krate.module.items = Vec::new();
            return (krate, Features::new());
        }

        features = get_features(&sess.span_diagnostic, &krate.attrs);

        // Avoid reconfiguring malformed `cfg_attr`s
        if err_count == sess.span_diagnostic.err_count() {
            strip_unconfigured.features = Some(&features);
            strip_unconfigured.configure(unconfigured_attrs);
        }
    }

    (krate, features)
}

macro_rules! configure {
    ($this:ident, $node:ident) => {
        match $this.configure($node) {
            Some(node) => node,
            None => return Default::default(),
        }
    };
}

impl<'a> StripUnconfigured<'a> {
    pub fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
        let node = self.process_cfg_attrs(node);
        if self.in_cfg(node.attrs()) {
            Some(node)
        } else {
            None
        }
    }

    pub fn process_cfg_attrs<T: HasAttrs>(&mut self, node: T) -> T {
        node.map_attrs(|attrs| {
            attrs
                .into_iter()
                .filter_map(|attr| self.process_cfg_attr(attr))
                .collect()
        })
    }

    fn process_cfg_attr(&mut self, attr: ast::Attribute) -> Option<ast::Attribute> {
        if !attr.check_name("cfg_attr") {
            return Some(attr);
        }

        let (cfg, path, tokens, span) = match attr.parse(self.sess, |parser| {
            parser.expect(&token::OpenDelim(token::Paren))?;
            let cfg = parser.parse_meta_item()?;
            parser.expect(&token::Comma)?;
            let lo = parser.span.lo;
            let (path, tokens) = parser.parse_path_and_tokens()?;
            parser.expect(&token::CloseDelim(token::Paren))?;
            Ok((
                cfg,
                path,
                tokens,
                Span {
                    lo: lo,
                    ..parser.prev_span
                },
            ))
        }) {
            Ok(result) => result,
            Err(mut e) => {
                e.emit();
                return None;
            }
        };

        if attr::cfg_matches(&cfg, self.sess, self.features) {
            self.process_cfg_attr(ast::Attribute {
                id: attr::mk_attr_id(),
                style: attr.style,
                path: path,
                tokens: tokens,
                is_sugared_doc: false,
                span: span,
            })
        } else {
            None
        }
    }

    // Determine if a node with the given attributes should be included in this configuation.
    pub fn in_cfg(&mut self, attrs: &[ast::Attribute]) -> bool {
        attrs.iter().all(|attr| {
            // When not compiling with --test we should not compile the #[test] functions
            if !self.should_test && is_test_or_bench(attr) {
                return false;
            }

            let mis = if !is_cfg(attr) {
                return true;
            } else if let Some(mis) = attr.meta_item_list() {
                mis
            } else {
                return true;
            };

            if mis.len() != 1 {
                self.sess
                    .span_diagnostic
                    .span_err(attr.span, "expected 1 cfg-pattern");
                return true;
            }

            if !mis[0].is_meta_item() {
                self.sess
                    .span_diagnostic
                    .span_err(mis[0].span, "unexpected literal");
                return true;
            }

            attr::cfg_matches(mis[0].meta_item().unwrap(), self.sess, self.features)
        })
    }

    // Visit attributes on expression and statements (but not attributes on items in blocks).
    fn visit_expr_attrs(&mut self, attrs: &[ast::Attribute]) {
        // flag the offending attributes
        for attr in attrs.iter() {
            if !self
                .features
                .map(|features| features.stmt_expr_attributes)
                .unwrap_or(true)
            {
                let mut err = feature_err(
                    self.sess,
                    "stmt_expr_attributes",
                    attr.span,
                    GateIssue::Language,
                    EXPLAIN_STMT_ATTR_SYNTAX,
                );
                if attr.is_sugared_doc {
                    err.help("`///` is for documentation comments. For a plain comment, use `//`.");
                }
                err.emit();
            }
        }
    }

    pub fn configure_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
        ast::ForeignMod {
            abi: foreign_mod.abi,
            items: foreign_mod
                .items
                .into_iter()
                .filter_map(|item| self.configure(item))
                .collect(),
        }
    }

    fn configure_variant_data(&mut self, vdata: ast::VariantData) -> ast::VariantData {
        match vdata {
            ast::VariantData::Struct(fields, id) => {
                let fields = fields.into_iter().filter_map(|field| self.configure(field));
                ast::VariantData::Struct(fields.collect(), id)
            }
            ast::VariantData::Tuple(fields, id) => {
                let fields = fields.into_iter().filter_map(|field| self.configure(field));
                ast::VariantData::Tuple(fields.collect(), id)
            }
            ast::VariantData::Unit(id) => ast::VariantData::Unit(id),
        }
    }

    pub fn configure_item_kind(&mut self, item: ast::ItemKind) -> ast::ItemKind {
        match item {
            ast::ItemKind::Struct(def, generics) => {
                ast::ItemKind::Struct(self.configure_variant_data(def), generics)
            }
            ast::ItemKind::Union(def, generics) => {
                ast::ItemKind::Union(self.configure_variant_data(def), generics)
            }
            ast::ItemKind::Enum(def, generics) => {
                let variants = def.variants.into_iter().filter_map(|v| {
                    self.configure(v).map(|v| Spanned {
                        node: ast::Variant_ {
                            name: v.node.name,
                            attrs: v.node.attrs,
                            data: self.configure_variant_data(v.node.data),
                            disr_expr: v.node.disr_expr,
                        },
                        span: v.span,
                    })
                });
                ast::ItemKind::Enum(
                    ast::EnumDef {
                        variants: variants.collect(),
                    },
                    generics,
                )
            }
            item => item,
        }
    }

    pub fn configure_expr_kind(&mut self, expr_kind: ast::ExprKind) -> ast::ExprKind {
        match expr_kind {
            ast::ExprKind::Match(m, arms) => {
                let arms = arms.into_iter().filter_map(|a| self.configure(a)).collect();
                ast::ExprKind::Match(m, arms)
            }
            ast::ExprKind::Struct(path, fields, base) => {
                let fields = fields
                    .into_iter()
                    .filter_map(|field| {
                        self.visit_struct_field_attrs(field.attrs());
                        self.configure(field)
                    })
                    .collect();
                ast::ExprKind::Struct(path, fields, base)
            }
            _ => expr_kind,
        }
    }

    pub fn configure_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
        self.visit_expr_attrs(expr.attrs());

        // If an expr is valid to cfg away it will have been removed by the
        // outer stmt or expression folder before descending in here.
        // Anything else is always required, and thus has to error out
        // in case of a cfg attr.
        //
        // NB: This is intentionally not part of the fold_expr() function
        //     in order for fold_opt_expr() to be able to avoid this check
        if let Some(attr) = expr
            .attrs()
            .iter()
            .find(|a| is_cfg(a) || is_test_or_bench(a))
        {
            let msg = "removing an expression is not supported in this position";
            self.sess.span_diagnostic.span_err(attr.span, msg);
        }

        self.process_cfg_attrs(expr)
    }

    pub fn configure_stmt(&mut self, stmt: ast::Stmt) -> Option<ast::Stmt> {
        self.configure(stmt)
    }

    pub fn configure_struct_expr_field(&mut self, field: ast::Field) -> Option<ast::Field> {
        if !self
            .features
            .map(|features| features.struct_field_attributes)
            .unwrap_or(true)
        {
            if !field.attrs.is_empty() {
                let mut err = feature_err(
                    self.sess,
                    "struct_field_attributes",
                    field.span,
                    GateIssue::Language,
                    "attributes on struct literal fields are unstable",
                );
                err.emit();
            }
        }

        self.configure(field)
    }

    pub fn configure_pat(&mut self, pattern: P<ast::Pat>) -> P<ast::Pat> {
        pattern.map(|mut pattern| {
            if let ast::PatKind::Struct(path, fields, etc) = pattern.node {
                let fields = fields
                    .into_iter()
                    .filter_map(|field| {
                        self.visit_struct_field_attrs(field.attrs());
                        self.configure(field)
                    })
                    .collect();
                pattern.node = ast::PatKind::Struct(path, fields, etc);
            }
            pattern
        })
    }

    fn visit_struct_field_attrs(&mut self, attrs: &[ast::Attribute]) {
        // flag the offending attributes
        for attr in attrs.iter() {
            if !self
                .features
                .map(|features| features.struct_field_attributes)
                .unwrap_or(true)
            {
                let mut err = feature_err(
                    self.sess,
                    "struct_field_attributes",
                    attr.span,
                    GateIssue::Language,
                    "attributes on struct pattern or literal fields are unstable",
                );
                err.emit();
            }
        }
    }
}

impl<'a> fold::Folder for StripUnconfigured<'a> {
    fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
        let foreign_mod = self.configure_foreign_mod(foreign_mod);
        fold::noop_fold_foreign_mod(foreign_mod, self)
    }

    fn fold_item_kind(&mut self, item: ast::ItemKind) -> ast::ItemKind {
        let item = self.configure_item_kind(item);
        fold::noop_fold_item_kind(item, self)
    }

    fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
        let mut expr = self.configure_expr(expr).unwrap();
        expr.node = self.configure_expr_kind(expr.node);
        P(fold::noop_fold_expr(expr, self))
    }

    fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
        let mut expr = configure!(self, expr).unwrap();
        expr.node = self.configure_expr_kind(expr.node);
        Some(P(fold::noop_fold_expr(expr, self)))
    }

    fn fold_stmt(&mut self, stmt: ast::Stmt) -> SmallVector<ast::Stmt> {
        match self.configure_stmt(stmt) {
            Some(stmt) => fold::noop_fold_stmt(stmt, self),
            None => return SmallVector::new(),
        }
    }

    fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
        fold::noop_fold_item(configure!(self, item), self)
    }

    fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVector<ast::ImplItem> {
        fold::noop_fold_impl_item(configure!(self, item), self)
    }

    fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVector<ast::TraitItem> {
        fold::noop_fold_trait_item(configure!(self, item), self)
    }

    fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
        // Don't configure interpolated AST (c.f. #34171).
        // Interpolated AST will get configured once the surrounding tokens are parsed.
        mac
    }

    fn fold_pat(&mut self, pattern: P<ast::Pat>) -> P<ast::Pat> {
        fold::noop_fold_pat(self.configure_pat(pattern), self)
    }
}

fn is_cfg(attr: &ast::Attribute) -> bool {
    attr.check_name("cfg")
}

pub fn is_test_or_bench(attr: &ast::Attribute) -> bool {
    attr.check_name("test") || attr.check_name("bench")
}