1 // 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.
21 #![feature(rustc_private)]
23 extern crate rustc_data_structures;
26 use rustc_data_structures::thin_vec::ThinVec;
28 use syntax::source_map::{Spanned, DUMMY_SP, FileName};
29 use syntax::source_map::FilePathMapping;
30 use syntax::mut_visit::{self, MutVisitor, visit_clobber};
31 use syntax::parse::{self, ParseSess};
32 use syntax::print::pprust;
36 fn parse_expr(ps: &ParseSess, src: &str) -> P<Expr> {
37 let src_as_string = src.to_string();
39 let mut p = parse::new_parser_from_source_str(ps,
40 FileName::Custom(src_as_string.clone()),
42 p.parse_expr().unwrap()
46 // Helper functions for building exprs
47 fn expr(kind: ExprKind) -> P<Expr> {
52 attrs: ThinVec::new(),
56 fn make_x() -> P<Expr> {
57 let seg = PathSegment::from_ident(Ident::from_str("x"));
58 let path = Path { segments: vec![seg], span: DUMMY_SP };
59 expr(ExprKind::Path(None, path))
62 /// Iterate over exprs of depth up to `depth`. The goal is to explore all "interesting"
63 /// combinations of expression nesting. For example, we explore combinations using `if`, but not
64 /// `while` or `match`, since those should print and parse in much the same way as `if`.
65 fn iter_exprs(depth: usize, f: &mut FnMut(P<Expr>)) {
71 let mut g = |e| f(expr(e));
75 0 => iter_exprs(depth - 1, &mut |e| g(ExprKind::Box(e))),
76 1 => iter_exprs(depth - 1, &mut |e| g(ExprKind::Call(e, vec![]))),
78 let seg = PathSegment::from_ident(Ident::from_str("x"));
79 iter_exprs(depth - 1, &mut |e| g(ExprKind::MethodCall(
80 seg.clone(), vec![e, make_x()])));
81 iter_exprs(depth - 1, &mut |e| g(ExprKind::MethodCall(
82 seg.clone(), vec![make_x(), e])));
85 let op = Spanned { span: DUMMY_SP, node: BinOpKind::Add };
86 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, e, make_x())));
87 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, make_x(), e)));
90 let op = Spanned { span: DUMMY_SP, node: BinOpKind::Mul };
91 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, e, make_x())));
92 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, make_x(), e)));
95 let op = Spanned { span: DUMMY_SP, node: BinOpKind::Shl };
96 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, e, make_x())));
97 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, make_x(), e)));
100 iter_exprs(depth - 1, &mut |e| g(ExprKind::Unary(UnOp::Deref, e)));
103 let block = P(Block {
106 rules: BlockCheckMode::Default,
109 iter_exprs(depth - 1, &mut |e| g(ExprKind::If(e, block.clone(), None)));
112 let decl = P(FnDecl {
114 output: FunctionRetTy::Default(DUMMY_SP),
117 iter_exprs(depth - 1, &mut |e| g(
118 ExprKind::Closure(CaptureBy::Value,
126 iter_exprs(depth - 1, &mut |e| g(ExprKind::Assign(e, make_x())));
127 iter_exprs(depth - 1, &mut |e| g(ExprKind::Assign(make_x(), e)));
130 iter_exprs(depth - 1, &mut |e| g(ExprKind::Field(e, Ident::from_str("f"))));
133 iter_exprs(depth - 1, &mut |e| g(ExprKind::Range(
134 Some(e), Some(make_x()), RangeLimits::HalfOpen)));
135 iter_exprs(depth - 1, &mut |e| g(ExprKind::Range(
136 Some(make_x()), Some(e), RangeLimits::HalfOpen)));
139 iter_exprs(depth - 1, &mut |e| g(ExprKind::AddrOf(Mutability::Immutable, e)));
142 g(ExprKind::Ret(None));
143 iter_exprs(depth - 1, &mut |e| g(ExprKind::Ret(Some(e))));
146 let path = Path::from_ident(Ident::from_str("S"));
147 g(ExprKind::Struct(path, vec![], Some(make_x())));
150 iter_exprs(depth - 1, &mut |e| g(ExprKind::Try(e)));
152 _ => panic!("bad counter value in iter_exprs"),
158 // Folders for manipulating the placement of `Paren` nodes. See below for why this is needed.
160 /// MutVisitor that removes all `ExprKind::Paren` nodes.
163 impl MutVisitor for RemoveParens {
164 fn visit_expr(&mut self, e: &mut P<Expr>) {
165 match e.node.clone() {
166 ExprKind::Paren(inner) => *e = inner,
169 mut_visit::noop_visit_expr(e, self);
174 /// MutVisitor that inserts `ExprKind::Paren` nodes around every `Expr`.
177 impl MutVisitor for AddParens {
178 fn visit_expr(&mut self, e: &mut P<Expr>) {
179 mut_visit::noop_visit_expr(e, self);
180 visit_clobber(e, |e| {
183 node: ExprKind::Paren(e),
185 attrs: ThinVec::new(),
192 syntax::with_globals(|| run());
196 let ps = ParseSess::new(FilePathMapping::empty());
198 iter_exprs(2, &mut |mut e| {
199 // If the pretty printer is correct, then `parse(print(e))` should be identical to `e`,
200 // modulo placement of `Paren` nodes.
201 let printed = pprust::expr_to_string(&e);
202 println!("printed: {}", printed);
204 let mut parsed = parse_expr(&ps, &printed);
206 // We want to know if `parsed` is structurally identical to `e`, ignoring trivial
207 // differences like placement of `Paren`s or the exact ranges of node spans.
208 // Unfortunately, there is no easy way to make this comparison. Instead, we add `Paren`s
209 // everywhere we can, then pretty-print. This should give an unambiguous representation of
210 // each `Expr`, and it bypasses nearly all of the parenthesization logic, so we aren't
211 // relying on the correctness of the very thing we're testing.
212 RemoveParens.visit_expr(&mut e);
213 AddParens.visit_expr(&mut e);
214 let text1 = pprust::expr_to_string(&e);
215 RemoveParens.visit_expr(&mut parsed);
216 AddParens.visit_expr(&mut parsed);
217 let text2 = pprust::expr_to_string(&parsed);
218 assert!(text1 == text2,
219 "exprs are not equal:\n e = {:?}\n parsed = {:?}",