2 // ignore-cross-compile
4 // The general idea of this test is to enumerate all "interesting" expressions and check that
5 // `parse(print(e)) == e` for all `e`. Here's what's interesting, for the purposes of this test:
7 // 1. The test focuses on expression nesting, because interactions between different expression
8 // types are harder to test manually than single expression types in isolation.
10 // 2. The test only considers expressions of at most two nontrivial nodes. So it will check `x +
11 // x` and `x + (x - x)` but not `(x * x) + (x - x)`. The assumption here is that the correct
12 // handling of an expression might depend on the expression's parent, but doesn't depend on its
13 // siblings or any more distant ancestors.
15 // 3. The test only checks certain expression kinds. The assumption is that similar expression
16 // types, such as `if` and `while` or `+` and `-`, will be handled identically in the printer
17 // and parser. So if all combinations of exprs involving `if` work correctly, then combinations
18 // using `while`, `if let`, and so on will likely work as well.
20 #![feature(rustc_private)]
22 extern crate rustc_ast_pretty;
23 extern crate rustc_data_structures;
24 extern crate rustc_ast;
25 extern crate rustc_parse;
26 extern crate rustc_session;
27 extern crate rustc_span;
29 use rustc_ast_pretty::pprust;
30 use rustc_data_structures::thin_vec::ThinVec;
31 use rustc_parse::new_parser_from_source_str;
32 use rustc_session::parse::ParseSess;
33 use rustc_span::source_map::{Spanned, DUMMY_SP, FileName};
34 use rustc_span::source_map::FilePathMapping;
35 use rustc_span::symbol::Ident;
37 use rustc_ast::mut_visit::{self, MutVisitor, visit_clobber};
38 use rustc_ast::ptr::P;
40 fn parse_expr(ps: &ParseSess, src: &str) -> Option<P<Expr>> {
41 let src_as_string = src.to_string();
43 let mut p = new_parser_from_source_str(
45 FileName::Custom(src_as_string.clone()),
48 p.parse_expr().map_err(|mut e| e.cancel()).ok()
52 // Helper functions for building exprs
53 fn expr(kind: ExprKind) -> P<Expr> {
58 attrs: ThinVec::new(),
63 fn make_x() -> P<Expr> {
64 let seg = PathSegment::from_ident(Ident::from_str("x"));
65 let path = Path { segments: vec![seg], span: DUMMY_SP, tokens: None };
66 expr(ExprKind::Path(None, path))
69 /// Iterate over exprs of depth up to `depth`. The goal is to explore all "interesting"
70 /// combinations of expression nesting. For example, we explore combinations using `if`, but not
71 /// `while` or `match`, since those should print and parse in much the same way as `if`.
72 fn iter_exprs(depth: usize, f: &mut dyn FnMut(P<Expr>)) {
78 let mut g = |e| f(expr(e));
82 0 => iter_exprs(depth - 1, &mut |e| g(ExprKind::Box(e))),
83 1 => iter_exprs(depth - 1, &mut |e| g(ExprKind::Call(e, vec![]))),
85 let seg = PathSegment::from_ident(Ident::from_str("x"));
86 iter_exprs(depth - 1, &mut |e| g(ExprKind::MethodCall(
87 seg.clone(), vec![e, make_x()], DUMMY_SP)));
88 iter_exprs(depth - 1, &mut |e| g(ExprKind::MethodCall(
89 seg.clone(), vec![make_x(), e], DUMMY_SP)));
104 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, e, make_x())));
105 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, make_x(), e)));
108 iter_exprs(depth - 1, &mut |e| g(ExprKind::Unary(UnOp::Deref, e)));
111 let block = P(Block {
114 rules: BlockCheckMode::Default,
118 iter_exprs(depth - 1, &mut |e| g(ExprKind::If(e, block.clone(), None)));
121 let decl = P(FnDecl {
123 output: FnRetTy::Default(DUMMY_SP),
125 iter_exprs(depth - 1, &mut |e| g(
126 ExprKind::Closure(CaptureBy::Value,
134 iter_exprs(depth - 1, &mut |e| g(ExprKind::Assign(e, make_x(), DUMMY_SP)));
135 iter_exprs(depth - 1, &mut |e| g(ExprKind::Assign(make_x(), e, DUMMY_SP)));
138 iter_exprs(depth - 1, &mut |e| g(ExprKind::Field(e, Ident::from_str("f"))));
141 iter_exprs(depth - 1, &mut |e| g(ExprKind::Range(
142 Some(e), Some(make_x()), RangeLimits::HalfOpen)));
143 iter_exprs(depth - 1, &mut |e| g(ExprKind::Range(
144 Some(make_x()), Some(e), RangeLimits::HalfOpen)));
149 &mut |e| g(ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, e)),
153 g(ExprKind::Ret(None));
154 iter_exprs(depth - 1, &mut |e| g(ExprKind::Ret(Some(e))));
157 let path = Path::from_ident(Ident::from_str("S"));
158 g(ExprKind::Struct(P(StructExpr {
159 path, fields: vec![], rest: StructRest::Base(make_x())
163 iter_exprs(depth - 1, &mut |e| g(ExprKind::Try(e)));
172 iter_exprs(depth - 1, &mut |e| g(ExprKind::Let(pat.clone(), e)))
174 _ => panic!("bad counter value in iter_exprs"),
180 // Folders for manipulating the placement of `Paren` nodes. See below for why this is needed.
182 /// `MutVisitor` that removes all `ExprKind::Paren` nodes.
185 impl MutVisitor for RemoveParens {
186 fn visit_expr(&mut self, e: &mut P<Expr>) {
187 match e.kind.clone() {
188 ExprKind::Paren(inner) => *e = inner,
191 mut_visit::noop_visit_expr(e, self);
196 /// `MutVisitor` that inserts `ExprKind::Paren` nodes around every `Expr`.
199 impl MutVisitor for AddParens {
200 fn visit_expr(&mut self, e: &mut P<Expr>) {
201 mut_visit::noop_visit_expr(e, self);
202 visit_clobber(e, |e| {
205 kind: ExprKind::Paren(e),
207 attrs: ThinVec::new(),
215 rustc_span::with_default_session_globals(|| run());
219 let ps = ParseSess::new(FilePathMapping::empty());
221 iter_exprs(2, &mut |mut e| {
222 // If the pretty printer is correct, then `parse(print(e))` should be identical to `e`,
223 // modulo placement of `Paren` nodes.
224 let printed = pprust::expr_to_string(&e);
225 println!("printed: {}", printed);
227 // Ignore expressions with chained comparisons that fail to parse
228 if let Some(mut parsed) = parse_expr(&ps, &printed) {
229 // We want to know if `parsed` is structurally identical to `e`, ignoring trivial
230 // differences like placement of `Paren`s or the exact ranges of node spans.
231 // Unfortunately, there is no easy way to make this comparison. Instead, we add `Paren`s
232 // everywhere we can, then pretty-print. This should give an unambiguous representation
233 // of each `Expr`, and it bypasses nearly all of the parenthesization logic, so we
234 // aren't relying on the correctness of the very thing we're testing.
235 RemoveParens.visit_expr(&mut e);
236 AddParens.visit_expr(&mut e);
237 let text1 = pprust::expr_to_string(&e);
238 RemoveParens.visit_expr(&mut parsed);
239 AddParens.visit_expr(&mut parsed);
240 let text2 = pprust::expr_to_string(&parsed);
241 assert!(text1 == text2,
242 "exprs are not equal:\n e = {:?}\n parsed = {:?}",