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;
23 extern crate rustc_ast_pretty;
24 extern crate rustc_data_structures;
25 extern crate rustc_parse;
26 extern crate rustc_session;
27 extern crate rustc_span;
29 use rustc_ast::mut_visit::{self, visit_clobber, MutVisitor};
30 use rustc_ast::ptr::P;
32 use rustc_ast_pretty::pprust;
33 use rustc_data_structures::thin_vec::ThinVec;
34 use rustc_parse::new_parser_from_source_str;
35 use rustc_session::parse::ParseSess;
36 use rustc_span::source_map::FilePathMapping;
37 use rustc_span::source_map::{FileName, Spanned, DUMMY_SP};
38 use rustc_span::symbol::Ident;
40 fn parse_expr(ps: &ParseSess, src: &str) -> Option<P<Expr>> {
41 let src_as_string = src.to_string();
44 new_parser_from_source_str(ps, FileName::Custom(src_as_string.clone()), src_as_string);
45 p.parse_expr().map_err(|e| e.cancel()).ok()
48 // Helper functions for building exprs
49 fn expr(kind: ExprKind) -> P<Expr> {
50 P(Expr { id: DUMMY_NODE_ID, kind, span: DUMMY_SP, attrs: ThinVec::new(), tokens: None })
53 fn make_x() -> P<Expr> {
54 let seg = PathSegment::from_ident(Ident::from_str("x"));
55 let path = Path { segments: vec![seg], span: DUMMY_SP, tokens: None };
56 expr(ExprKind::Path(None, path))
59 /// Iterate over exprs of depth up to `depth`. The goal is to explore all "interesting"
60 /// combinations of expression nesting. For example, we explore combinations using `if`, but not
61 /// `while` or `match`, since those should print and parse in much the same way as `if`.
62 fn iter_exprs(depth: usize, f: &mut dyn FnMut(P<Expr>)) {
68 let mut g = |e| f(expr(e));
72 0 => iter_exprs(depth - 1, &mut |e| g(ExprKind::Box(e))),
73 1 => iter_exprs(depth - 1, &mut |e| g(ExprKind::Call(e, vec![]))),
75 let seg = PathSegment::from_ident(Ident::from_str("x"));
76 iter_exprs(depth - 1, &mut |e| {
77 g(ExprKind::MethodCall(seg.clone(), vec![e, make_x()], DUMMY_SP))
79 iter_exprs(depth - 1, &mut |e| {
80 g(ExprKind::MethodCall(seg.clone(), vec![make_x(), e], DUMMY_SP))
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 could_be_bare_literal: false,
111 iter_exprs(depth - 1, &mut |e| g(ExprKind::If(e, block.clone(), None)));
114 let decl = P(FnDecl { inputs: vec![], output: FnRetTy::Default(DUMMY_SP) });
115 iter_exprs(depth - 1, &mut |e| {
117 ClosureBinder::NotPresent,
128 iter_exprs(depth - 1, &mut |e| g(ExprKind::Assign(e, make_x(), DUMMY_SP)));
129 iter_exprs(depth - 1, &mut |e| g(ExprKind::Assign(make_x(), e, DUMMY_SP)));
132 iter_exprs(depth - 1, &mut |e| g(ExprKind::Field(e, Ident::from_str("f"))));
135 iter_exprs(depth - 1, &mut |e| {
136 g(ExprKind::Range(Some(e), Some(make_x()), RangeLimits::HalfOpen))
138 iter_exprs(depth - 1, &mut |e| {
139 g(ExprKind::Range(Some(make_x()), Some(e), RangeLimits::HalfOpen))
143 iter_exprs(depth - 1, &mut |e| {
144 g(ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, e))
148 g(ExprKind::Ret(None));
149 iter_exprs(depth - 1, &mut |e| g(ExprKind::Ret(Some(e))));
152 let path = Path::from_ident(Ident::from_str("S"));
153 g(ExprKind::Struct(P(StructExpr {
157 rest: StructRest::Base(make_x()),
161 iter_exprs(depth - 1, &mut |e| g(ExprKind::Try(e)));
165 P(Pat { id: DUMMY_NODE_ID, kind: PatKind::Wild, span: DUMMY_SP, tokens: None });
166 iter_exprs(depth - 1, &mut |e| g(ExprKind::Let(pat.clone(), e, DUMMY_SP)))
168 _ => panic!("bad counter value in iter_exprs"),
173 // Folders for manipulating the placement of `Paren` nodes. See below for why this is needed.
175 /// `MutVisitor` that removes all `ExprKind::Paren` nodes.
178 impl MutVisitor for RemoveParens {
179 fn visit_expr(&mut self, e: &mut P<Expr>) {
180 match e.kind.clone() {
181 ExprKind::Paren(inner) => *e = inner,
184 mut_visit::noop_visit_expr(e, self);
188 /// `MutVisitor` that inserts `ExprKind::Paren` nodes around every `Expr`.
191 impl MutVisitor for AddParens {
192 fn visit_expr(&mut self, e: &mut P<Expr>) {
193 mut_visit::noop_visit_expr(e, self);
194 visit_clobber(e, |e| {
197 kind: ExprKind::Paren(e),
199 attrs: ThinVec::new(),
207 rustc_span::create_default_session_globals_then(|| run());
211 let ps = ParseSess::new(FilePathMapping::empty());
213 iter_exprs(2, &mut |mut e| {
214 // If the pretty printer is correct, then `parse(print(e))` should be identical to `e`,
215 // modulo placement of `Paren` nodes.
216 let printed = pprust::expr_to_string(&e);
217 println!("printed: {}", printed);
219 // Ignore expressions with chained comparisons that fail to parse
220 if let Some(mut parsed) = parse_expr(&ps, &printed) {
221 // We want to know if `parsed` is structurally identical to `e`, ignoring trivial
222 // differences like placement of `Paren`s or the exact ranges of node spans.
223 // Unfortunately, there is no easy way to make this comparison. Instead, we add `Paren`s
224 // everywhere we can, then pretty-print. This should give an unambiguous representation
225 // of each `Expr`, and it bypasses nearly all of the parenthesization logic, so we
226 // aren't relying on the correctness of the very thing we're testing.
227 RemoveParens.visit_expr(&mut e);
228 AddParens.visit_expr(&mut e);
229 let text1 = pprust::expr_to_string(&e);
230 RemoveParens.visit_expr(&mut parsed);
231 AddParens.visit_expr(&mut parsed);
232 let text2 = pprust::expr_to_string(&parsed);
235 "exprs are not equal:\n e = {:?}\n parsed = {:?}",