1 // ignore-cross-compile
3 // The general idea of this test is to enumerate all "interesting" expressions and check that
4 // `parse(print(e)) == e` for all `e`. Here's what's interesting, for the purposes of this test:
6 // 1. The test focuses on expression nesting, because interactions between different expression
7 // types are harder to test manually than single expression types in isolation.
9 // 2. The test only considers expressions of at most two nontrivial nodes. So it will check `x +
10 // x` and `x + (x - x)` but not `(x * x) + (x - x)`. The assumption here is that the correct
11 // handling of an expression might depend on the expression's parent, but doesn't depend on its
12 // siblings or any more distant ancestors.
14 // 3. The test only checks certain expression kinds. The assumption is that similar expression
15 // types, such as `if` and `while` or `+` and `-`, will be handled identically in the printer
16 // and parser. So if all combinations of exprs involving `if` work correctly, then combinations
17 // using `while`, `if let`, and so on will likely work as well.
19 #![feature(rustc_private)]
21 extern crate rustc_data_structures;
24 use rustc_data_structures::thin_vec::ThinVec;
26 use syntax::source_map::{Spanned, DUMMY_SP, FileName};
27 use syntax::source_map::FilePathMapping;
28 use syntax::mut_visit::{self, MutVisitor, visit_clobber};
29 use syntax::parse::{self, ParseSess};
30 use syntax::print::pprust;
34 fn parse_expr(ps: &ParseSess, src: &str) -> P<Expr> {
35 let src_as_string = src.to_string();
37 let mut p = parse::new_parser_from_source_str(ps,
38 FileName::Custom(src_as_string.clone()),
40 p.parse_expr().unwrap()
44 // Helper functions for building exprs
45 fn expr(kind: ExprKind) -> P<Expr> {
50 attrs: ThinVec::new(),
54 fn make_x() -> P<Expr> {
55 let seg = PathSegment::from_ident(Ident::from_str("x"));
56 let path = Path { segments: vec![seg], span: DUMMY_SP };
57 expr(ExprKind::Path(None, path))
60 /// Iterate over exprs of depth up to `depth`. The goal is to explore all "interesting"
61 /// combinations of expression nesting. For example, we explore combinations using `if`, but not
62 /// `while` or `match`, since those should print and parse in much the same way as `if`.
63 fn iter_exprs(depth: usize, f: &mut dyn FnMut(P<Expr>)) {
69 let mut g = |e| f(expr(e));
73 0 => iter_exprs(depth - 1, &mut |e| g(ExprKind::Box(e))),
74 1 => iter_exprs(depth - 1, &mut |e| g(ExprKind::Call(e, vec![]))),
76 let seg = PathSegment::from_ident(Ident::from_str("x"));
77 iter_exprs(depth - 1, &mut |e| g(ExprKind::MethodCall(
78 seg.clone(), vec![e, make_x()])));
79 iter_exprs(depth - 1, &mut |e| g(ExprKind::MethodCall(
80 seg.clone(), vec![make_x(), e])));
83 let op = Spanned { span: DUMMY_SP, node: BinOpKind::Add };
84 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, e, make_x())));
85 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, make_x(), e)));
88 let op = Spanned { span: DUMMY_SP, node: BinOpKind::Mul };
89 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, e, make_x())));
90 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, make_x(), e)));
93 let op = Spanned { span: DUMMY_SP, node: BinOpKind::Shl };
94 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, e, make_x())));
95 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, make_x(), e)));
98 iter_exprs(depth - 1, &mut |e| g(ExprKind::Unary(UnOp::Deref, e)));
101 let block = P(Block {
104 rules: BlockCheckMode::Default,
107 iter_exprs(depth - 1, &mut |e| g(ExprKind::If(e, block.clone(), None)));
110 let decl = P(FnDecl {
112 output: FunctionRetTy::Default(DUMMY_SP),
115 iter_exprs(depth - 1, &mut |e| g(
116 ExprKind::Closure(CaptureBy::Value,
124 iter_exprs(depth - 1, &mut |e| g(ExprKind::Assign(e, make_x())));
125 iter_exprs(depth - 1, &mut |e| g(ExprKind::Assign(make_x(), e)));
128 iter_exprs(depth - 1, &mut |e| g(ExprKind::Field(e, Ident::from_str("f"))));
131 iter_exprs(depth - 1, &mut |e| g(ExprKind::Range(
132 Some(e), Some(make_x()), RangeLimits::HalfOpen)));
133 iter_exprs(depth - 1, &mut |e| g(ExprKind::Range(
134 Some(make_x()), Some(e), RangeLimits::HalfOpen)));
137 iter_exprs(depth - 1, &mut |e| g(ExprKind::AddrOf(Mutability::Immutable, e)));
140 g(ExprKind::Ret(None));
141 iter_exprs(depth - 1, &mut |e| g(ExprKind::Ret(Some(e))));
144 let path = Path::from_ident(Ident::from_str("S"));
145 g(ExprKind::Struct(path, vec![], Some(make_x())));
148 iter_exprs(depth - 1, &mut |e| g(ExprKind::Try(e)));
150 _ => panic!("bad counter value in iter_exprs"),
156 // Folders for manipulating the placement of `Paren` nodes. See below for why this is needed.
158 /// `MutVisitor` that removes all `ExprKind::Paren` nodes.
161 impl MutVisitor for RemoveParens {
162 fn visit_expr(&mut self, e: &mut P<Expr>) {
163 match e.node.clone() {
164 ExprKind::Paren(inner) => *e = inner,
167 mut_visit::noop_visit_expr(e, self);
172 /// `MutVisitor` that inserts `ExprKind::Paren` nodes around every `Expr`.
175 impl MutVisitor for AddParens {
176 fn visit_expr(&mut self, e: &mut P<Expr>) {
177 mut_visit::noop_visit_expr(e, self);
178 visit_clobber(e, |e| {
181 node: ExprKind::Paren(e),
183 attrs: ThinVec::new(),
190 syntax::with_default_globals(|| run());
194 let ps = ParseSess::new(FilePathMapping::empty());
196 iter_exprs(2, &mut |mut e| {
197 // If the pretty printer is correct, then `parse(print(e))` should be identical to `e`,
198 // modulo placement of `Paren` nodes.
199 let printed = pprust::expr_to_string(&e);
200 println!("printed: {}", printed);
202 let mut parsed = parse_expr(&ps, &printed);
204 // We want to know if `parsed` is structurally identical to `e`, ignoring trivial
205 // differences like placement of `Paren`s or the exact ranges of node spans.
206 // Unfortunately, there is no easy way to make this comparison. Instead, we add `Paren`s
207 // everywhere we can, then pretty-print. This should give an unambiguous representation of
208 // each `Expr`, and it bypasses nearly all of the parenthesization logic, so we aren't
209 // relying on the correctness of the very thing we're testing.
210 RemoveParens.visit_expr(&mut e);
211 AddParens.visit_expr(&mut e);
212 let text1 = pprust::expr_to_string(&e);
213 RemoveParens.visit_expr(&mut parsed);
214 AddParens.visit_expr(&mut parsed);
215 let text2 = pprust::expr_to_string(&parsed);
216 assert!(text1 == text2,
217 "exprs are not equal:\n e = {:?}\n parsed = {:?}",