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Commit | Line | Data |
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416331ca XL |
1 | // run-pass |
2 | ||
0bf4aa26 XL |
3 | #![allow(unused_must_use)] |
4 | #![allow(unused_parens)] | |
223e47cc LB |
5 | // This test has some extra semis in it that the pretty-printer won't |
6 | // reproduce so we don't want to automatically reformat it | |
7 | ||
8 | // no-reformat | |
9 | ||
c34b1796 | 10 | |
223e47cc LB |
11 | /* |
12 | * | |
13 | * When you write a block-expression thing followed by | |
14 | * a lone unary operator, you can get a surprising parse: | |
15 | * | |
16 | * if (...) { ... } | |
17 | * -num; | |
18 | * | |
19 | * for example, or: | |
20 | * | |
21 | * if (...) { ... } | |
22 | * *box; | |
23 | * | |
24 | * These will parse as subtraction and multiplication binops. | |
25 | * To get them to parse "the way you want" you need to brace | |
26 | * the leading unops: | |
27 | ||
28 | * if (...) { ... } | |
29 | * {-num}; | |
30 | * | |
31 | * or alternatively, semi-separate them: | |
32 | * | |
33 | * if (...) { ... }; | |
34 | * -num; | |
35 | * | |
36 | * This seems a little wonky, but the alternative is to lower | |
37 | * precedence of such block-like exprs to the point where | |
38 | * you have to parenthesize them to get them to occur in the | |
39 | * RHS of a binop. For example, you'd have to write: | |
40 | * | |
41 | * 12 + (if (foo) { 13 } else { 14 }); | |
42 | * | |
43 | * rather than: | |
44 | * | |
45 | * 12 + if (foo) { 13 } else { 14 }; | |
46 | * | |
47 | * Since we want to maintain the ability to write the latter, | |
48 | * we leave the parens-burden on the trailing unop case. | |
49 | * | |
50 | */ | |
51 | ||
52 | pub fn main() { | |
53 | ||
54 | let num = 12; | |
55 | ||
85aaf69f SL |
56 | assert_eq!(if (true) { 12 } else { 12 } - num, 0); |
57 | assert_eq!(12 - if (true) { 12 } else { 12 }, 0); | |
58 | if (true) { 12; } {-num}; | |
59 | if (true) { 12; }; {-num}; | |
60 | if (true) { 12; };;; -num; | |
60c5eb7d | 61 | //~^ WARNING unnecessary trailing semicolons |
223e47cc | 62 | } |