mirror of https://github.com/rust-lang/rust
60 lines
1.6 KiB
Rust
60 lines
1.6 KiB
Rust
//@ run-pass
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#![allow(non_upper_case_globals)]
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// Issue #13186
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// For simplicity of explanations assuming code is compiled for x86_64
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// Linux ABI.
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// Size of TestOption<u64> is 16, and alignment of TestOption<u64> is 8.
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// Size of u8 is 1, and alignment of u8 is 1.
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// So size of Request is 24, and alignment of Request must be 8:
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// the maximum alignment of its fields.
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// Last 7 bytes of Request struct are not occupied by any fields.
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enum TestOption<T> {
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TestNone,
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TestSome(T),
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}
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pub struct Request {
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foo: TestOption<u64>,
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bar: u8,
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}
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fn default_instance() -> &'static Request {
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static instance: Request = Request {
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// LLVM does not allow to specify alignment of expressions, thus
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// alignment of `foo` in constant is 1, not 8.
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foo: TestOption::TestNone,
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bar: 17,
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// Space after last field is not occupied by any data, but it is
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// reserved to make struct aligned properly. If compiler does
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// not insert padding after last field when emitting constant,
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// size of struct may be not equal to size of struct, and
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// compiler crashes in internal assertion check.
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};
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&instance
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}
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fn non_default_instance() -> &'static Request {
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static instance: Request = Request {
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foo: TestOption::TestSome(0x1020304050607080),
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bar: 19,
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};
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&instance
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}
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pub fn main() {
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match default_instance() {
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&Request { foo: TestOption::TestNone, bar: 17 } => {},
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_ => panic!(),
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};
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match non_default_instance() {
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&Request { foo: TestOption::TestSome(0x1020304050607080), bar: 19 } => {},
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_ => panic!(),
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};
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}
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