264 lines
10 KiB
Rust
264 lines
10 KiB
Rust
//@ run-pass
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//@ ignore-cross-compile
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// The general idea of this test is to enumerate all "interesting" expressions and check that
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// `parse(print(e)) == e` for all `e`. Here's what's interesting, for the purposes of this test:
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//
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// 1. The test focuses on expression nesting, because interactions between different expression
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// types are harder to test manually than single expression types in isolation.
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//
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// 2. The test only considers expressions of at most two nontrivial nodes. So it will check `x +
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// x` and `x + (x - x)` but not `(x * x) + (x - x)`. The assumption here is that the correct
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// handling of an expression might depend on the expression's parent, but doesn't depend on its
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// siblings or any more distant ancestors.
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//
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// 3. The test only checks certain expression kinds. The assumption is that similar expression
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// types, such as `if` and `while` or `+` and `-`, will be handled identically in the printer
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// and parser. So if all combinations of exprs involving `if` work correctly, then combinations
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// using `while`, `if let`, and so on will likely work as well.
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#![feature(rustc_private)]
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extern crate rustc_ast;
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extern crate rustc_ast_pretty;
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extern crate rustc_data_structures;
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extern crate rustc_parse;
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extern crate rustc_session;
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extern crate rustc_span;
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extern crate thin_vec;
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// Necessary to pull in object code as the rest of the rustc crates are shipped only as rmeta
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// files.
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#[allow(unused_extern_crates)]
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extern crate rustc_driver;
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use rustc_ast::mut_visit::{visit_clobber, MutVisitor};
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use rustc_ast::ptr::P;
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use rustc_ast::*;
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use rustc_ast_pretty::pprust;
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use rustc_parse::{new_parser_from_source_str, unwrap_or_emit_fatal};
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use rustc_session::parse::ParseSess;
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use rustc_span::source_map::Spanned;
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use rustc_span::symbol::Ident;
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use rustc_span::{FileName, DUMMY_SP};
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use thin_vec::{thin_vec, ThinVec};
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fn parse_expr(psess: &ParseSess, src: &str) -> Option<P<Expr>> {
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let src_as_string = src.to_string();
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let mut p = unwrap_or_emit_fatal(new_parser_from_source_str(
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psess,
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FileName::Custom(src_as_string.clone()),
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src_as_string,
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));
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p.parse_expr().map_err(|e| e.cancel()).ok()
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}
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// Helper functions for building exprs
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fn expr(kind: ExprKind) -> P<Expr> {
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P(Expr { id: DUMMY_NODE_ID, kind, span: DUMMY_SP, attrs: AttrVec::new(), tokens: None })
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}
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fn make_x() -> P<Expr> {
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let seg = PathSegment::from_ident(Ident::from_str("x"));
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let path = Path { segments: thin_vec![seg], span: DUMMY_SP, tokens: None };
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expr(ExprKind::Path(None, path))
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}
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/// Iterate over exprs of depth up to `depth`. The goal is to explore all "interesting"
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/// combinations of expression nesting. For example, we explore combinations using `if`, but not
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/// `while` or `match`, since those should print and parse in much the same way as `if`.
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fn iter_exprs(depth: usize, f: &mut dyn FnMut(P<Expr>)) {
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if depth == 0 {
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f(make_x());
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return;
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}
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let mut g = |e| f(expr(e));
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for kind in 0..=18 {
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match kind {
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0 => iter_exprs(depth - 1, &mut |e| g(ExprKind::Call(e, thin_vec![]))),
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1 => {
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let seg = PathSegment::from_ident(Ident::from_str("x"));
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iter_exprs(depth - 1, &mut |e| {
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g(ExprKind::MethodCall(Box::new(MethodCall {
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seg: seg.clone(),
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receiver: e,
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args: thin_vec![make_x()],
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span: DUMMY_SP,
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})))
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});
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iter_exprs(depth - 1, &mut |e| {
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g(ExprKind::MethodCall(Box::new(MethodCall {
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seg: seg.clone(),
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receiver: make_x(),
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args: thin_vec![e],
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span: DUMMY_SP,
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})))
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});
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}
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2..=7 => {
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let op = Spanned {
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span: DUMMY_SP,
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node: match kind {
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2 => BinOpKind::Add,
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3 => BinOpKind::Mul,
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4 => BinOpKind::Shl,
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5 => BinOpKind::And,
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6 => BinOpKind::Or,
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7 => BinOpKind::Lt,
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_ => unreachable!(),
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},
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};
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iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, e, make_x())));
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iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, make_x(), e)));
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}
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8 => {
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iter_exprs(depth - 1, &mut |e| g(ExprKind::Unary(UnOp::Deref, e)));
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}
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9 => {
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let block = P(Block {
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stmts: ThinVec::new(),
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id: DUMMY_NODE_ID,
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rules: BlockCheckMode::Default,
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span: DUMMY_SP,
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tokens: None,
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could_be_bare_literal: false,
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});
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iter_exprs(depth - 1, &mut |e| g(ExprKind::If(e, block.clone(), None)));
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}
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10 => {
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let decl = P(FnDecl { inputs: thin_vec![], output: FnRetTy::Default(DUMMY_SP) });
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iter_exprs(depth - 1, &mut |e| {
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g(ExprKind::Closure(Box::new(Closure {
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binder: ClosureBinder::NotPresent,
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capture_clause: CaptureBy::Value { move_kw: DUMMY_SP },
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constness: Const::No,
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coroutine_kind: None,
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movability: Movability::Movable,
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fn_decl: decl.clone(),
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body: e,
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fn_decl_span: DUMMY_SP,
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fn_arg_span: DUMMY_SP,
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})))
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});
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}
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11 => {
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iter_exprs(depth - 1, &mut |e| g(ExprKind::Assign(e, make_x(), DUMMY_SP)));
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iter_exprs(depth - 1, &mut |e| g(ExprKind::Assign(make_x(), e, DUMMY_SP)));
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}
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12 => {
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iter_exprs(depth - 1, &mut |e| g(ExprKind::Field(e, Ident::from_str("f"))));
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}
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13 => {
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iter_exprs(depth - 1, &mut |e| {
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g(ExprKind::Range(Some(e), Some(make_x()), RangeLimits::HalfOpen))
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});
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iter_exprs(depth - 1, &mut |e| {
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g(ExprKind::Range(Some(make_x()), Some(e), RangeLimits::HalfOpen))
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});
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}
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14 => {
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iter_exprs(depth - 1, &mut |e| {
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g(ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, e))
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});
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}
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15 => {
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g(ExprKind::Ret(None));
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iter_exprs(depth - 1, &mut |e| g(ExprKind::Ret(Some(e))));
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}
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16 => {
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let path = Path::from_ident(Ident::from_str("S"));
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g(ExprKind::Struct(P(StructExpr {
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qself: None,
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path,
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fields: thin_vec![],
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rest: StructRest::Base(make_x()),
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})));
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}
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17 => {
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iter_exprs(depth - 1, &mut |e| g(ExprKind::Try(e)));
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}
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18 => {
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let pat =
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P(Pat { id: DUMMY_NODE_ID, kind: PatKind::Wild, span: DUMMY_SP, tokens: None });
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iter_exprs(depth - 1, &mut |e| {
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g(ExprKind::Let(pat.clone(), e, DUMMY_SP, Recovered::No))
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})
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}
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_ => panic!("bad counter value in iter_exprs"),
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}
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}
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}
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// Folders for manipulating the placement of `Paren` nodes. See below for why this is needed.
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/// `MutVisitor` that removes all `ExprKind::Paren` nodes.
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struct RemoveParens;
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impl MutVisitor for RemoveParens {
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fn visit_expr(&mut self, e: &mut P<Expr>) {
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match e.kind.clone() {
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ExprKind::Paren(inner) => *e = inner,
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_ => {}
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};
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mut_visit::walk_expr(self, e);
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}
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}
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/// `MutVisitor` that inserts `ExprKind::Paren` nodes around every `Expr`.
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struct AddParens;
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impl MutVisitor for AddParens {
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fn visit_expr(&mut self, e: &mut P<Expr>) {
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mut_visit::walk_expr(self, e);
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visit_clobber(e, |e| {
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P(Expr {
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id: DUMMY_NODE_ID,
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kind: ExprKind::Paren(e),
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span: DUMMY_SP,
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attrs: AttrVec::new(),
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tokens: None,
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})
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});
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}
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}
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fn main() {
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rustc_span::create_default_session_globals_then(|| run());
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}
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fn run() {
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let psess = ParseSess::new(vec![rustc_parse::DEFAULT_LOCALE_RESOURCE]);
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iter_exprs(2, &mut |mut e| {
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// If the pretty printer is correct, then `parse(print(e))` should be identical to `e`,
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// modulo placement of `Paren` nodes.
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let printed = pprust::expr_to_string(&e);
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println!("printed: {}", printed);
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// Ignore expressions with chained comparisons that fail to parse
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if let Some(mut parsed) = parse_expr(&psess, &printed) {
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// We want to know if `parsed` is structurally identical to `e`, ignoring trivial
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// differences like placement of `Paren`s or the exact ranges of node spans.
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// Unfortunately, there is no easy way to make this comparison. Instead, we add `Paren`s
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// everywhere we can, then pretty-print. This should give an unambiguous representation
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// of each `Expr`, and it bypasses nearly all of the parenthesization logic, so we
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// aren't relying on the correctness of the very thing we're testing.
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RemoveParens.visit_expr(&mut e);
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AddParens.visit_expr(&mut e);
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let text1 = pprust::expr_to_string(&e);
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RemoveParens.visit_expr(&mut parsed);
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AddParens.visit_expr(&mut parsed);
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let text2 = pprust::expr_to_string(&parsed);
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assert!(
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text1 == text2,
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"exprs are not equal:\n e = {:?}\n parsed = {:?}",
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text1,
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text2
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);
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}
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});
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}
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