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_parse::new_parser_from_source_str;
34 use rustc_session::parse::ParseSess;
35 use rustc_span::source_map::FilePathMapping;
36 use rustc_span::source_map::{FileName, Spanned, DUMMY_SP};
37 use rustc_span::symbol::Ident;
39 fn parse_expr(ps: &ParseSess, src: &str) -> Option<P<Expr>> {
40 let src_as_string = src.to_string();
43 new_parser_from_source_str(ps, FileName::Custom(src_as_string.clone()), src_as_string);
44 p.parse_expr().map_err(|e| e.cancel()).ok()
47 // Helper functions for building exprs
48 fn expr(kind: ExprKind) -> P<Expr> {
49 P(Expr { id: DUMMY_NODE_ID, kind, span: DUMMY_SP, attrs: AttrVec::new(), tokens: None })
52 fn make_x() -> P<Expr> {
53 let seg = PathSegment::from_ident(Ident::from_str("x"));
54 let path = Path { segments: vec![seg], span: DUMMY_SP, tokens: None };
55 expr(ExprKind::Path(None, path))
58 /// Iterate over exprs of depth up to `depth`. The goal is to explore all "interesting"
59 /// combinations of expression nesting. For example, we explore combinations using `if`, but not
60 /// `while` or `match`, since those should print and parse in much the same way as `if`.
61 fn iter_exprs(depth: usize, f: &mut dyn FnMut(P<Expr>)) {
67 let mut g = |e| f(expr(e));
71 0 => iter_exprs(depth - 1, &mut |e| g(ExprKind::Box(e))),
72 1 => iter_exprs(depth - 1, &mut |e| g(ExprKind::Call(e, vec![]))),
74 let seg = PathSegment::from_ident(Ident::from_str("x"));
75 iter_exprs(depth - 1, &mut |e| {
76 g(ExprKind::MethodCall(seg.clone(), e, vec![make_x()], DUMMY_SP))
78 iter_exprs(depth - 1, &mut |e| {
79 g(ExprKind::MethodCall(seg.clone(), make_x(), vec![e], DUMMY_SP))
95 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, e, make_x())));
96 iter_exprs(depth - 1, &mut |e| g(ExprKind::Binary(op, make_x(), e)));
99 iter_exprs(depth - 1, &mut |e| g(ExprKind::Unary(UnOp::Deref, e)));
102 let block = P(Block {
105 rules: BlockCheckMode::Default,
108 could_be_bare_literal: false,
110 iter_exprs(depth - 1, &mut |e| g(ExprKind::If(e, block.clone(), None)));
113 let decl = P(FnDecl { inputs: vec![], output: FnRetTy::Default(DUMMY_SP) });
114 iter_exprs(depth - 1, &mut |e| {
116 ClosureBinder::NotPresent,
127 iter_exprs(depth - 1, &mut |e| g(ExprKind::Assign(e, make_x(), DUMMY_SP)));
128 iter_exprs(depth - 1, &mut |e| g(ExprKind::Assign(make_x(), e, DUMMY_SP)));
131 iter_exprs(depth - 1, &mut |e| g(ExprKind::Field(e, Ident::from_str("f"))));
134 iter_exprs(depth - 1, &mut |e| {
135 g(ExprKind::Range(Some(e), Some(make_x()), RangeLimits::HalfOpen))
137 iter_exprs(depth - 1, &mut |e| {
138 g(ExprKind::Range(Some(make_x()), Some(e), RangeLimits::HalfOpen))
142 iter_exprs(depth - 1, &mut |e| {
143 g(ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, e))
147 g(ExprKind::Ret(None));
148 iter_exprs(depth - 1, &mut |e| g(ExprKind::Ret(Some(e))));
151 let path = Path::from_ident(Ident::from_str("S"));
152 g(ExprKind::Struct(P(StructExpr {
156 rest: StructRest::Base(make_x()),
160 iter_exprs(depth - 1, &mut |e| g(ExprKind::Try(e)));
164 P(Pat { id: DUMMY_NODE_ID, kind: PatKind::Wild, span: DUMMY_SP, tokens: None });
165 iter_exprs(depth - 1, &mut |e| g(ExprKind::Let(pat.clone(), e, DUMMY_SP)))
167 _ => panic!("bad counter value in iter_exprs"),
172 // Folders for manipulating the placement of `Paren` nodes. See below for why this is needed.
174 /// `MutVisitor` that removes all `ExprKind::Paren` nodes.
177 impl MutVisitor for RemoveParens {
178 fn visit_expr(&mut self, e: &mut P<Expr>) {
179 match e.kind.clone() {
180 ExprKind::Paren(inner) => *e = inner,
183 mut_visit::noop_visit_expr(e, self);
187 /// `MutVisitor` that inserts `ExprKind::Paren` nodes around every `Expr`.
190 impl MutVisitor for AddParens {
191 fn visit_expr(&mut self, e: &mut P<Expr>) {
192 mut_visit::noop_visit_expr(e, self);
193 visit_clobber(e, |e| {
196 kind: ExprKind::Paren(e),
198 attrs: AttrVec::new(),
206 rustc_span::create_default_session_globals_then(|| run());
210 let ps = ParseSess::new(FilePathMapping::empty());
212 iter_exprs(2, &mut |mut e| {
213 // If the pretty printer is correct, then `parse(print(e))` should be identical to `e`,
214 // modulo placement of `Paren` nodes.
215 let printed = pprust::expr_to_string(&e);
216 println!("printed: {}", printed);
218 // Ignore expressions with chained comparisons that fail to parse
219 if let Some(mut parsed) = parse_expr(&ps, &printed) {
220 // We want to know if `parsed` is structurally identical to `e`, ignoring trivial
221 // differences like placement of `Paren`s or the exact ranges of node spans.
222 // Unfortunately, there is no easy way to make this comparison. Instead, we add `Paren`s
223 // everywhere we can, then pretty-print. This should give an unambiguous representation
224 // of each `Expr`, and it bypasses nearly all of the parenthesization logic, so we
225 // aren't relying on the correctness of the very thing we're testing.
226 RemoveParens.visit_expr(&mut e);
227 AddParens.visit_expr(&mut e);
228 let text1 = pprust::expr_to_string(&e);
229 RemoveParens.visit_expr(&mut parsed);
230 AddParens.visit_expr(&mut parsed);
231 let text2 = pprust::expr_to_string(&parsed);
234 "exprs are not equal:\n e = {:?}\n parsed = {:?}",