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Support [x; n] expressions in concat_bytes!
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Contributes to rust-lang#87555.
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@syvb
syvb committed Dec 18, 2021
1 parent 7abab1e commit 3173151
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Showing 4 changed files with 135 additions and 42 deletions.
105 changes: 65 additions & 40 deletions compiler/rustc_builtin_macros/src/concat_bytes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,52 @@ fn invalid_type_err(cx: &mut base::ExtCtxt<'_>, expr: &P<rustc_ast::Expr>, is_ne
}
}

fn handle_array_element(
cx: &mut base::ExtCtxt<'_>,
has_errors: &mut bool,
missing_literals: &mut Vec<rustc_span::Span>,
expr: &P<rustc_ast::Expr>,
) -> Option<u8> {
match expr.kind {
ast::ExprKind::Array(_) | ast::ExprKind::Repeat(_, _) => {
if !*has_errors {
cx.span_err(expr.span, "cannot concatenate doubly nested array");
}
*has_errors = true;
None
}
ast::ExprKind::Lit(ref lit) => match lit.kind {
ast::LitKind::Int(
val,
ast::LitIntType::Unsuffixed | ast::LitIntType::Unsigned(ast::UintTy::U8),
) if val <= u8::MAX.into() => Some(val as u8),

ast::LitKind::Byte(val) => Some(val),
ast::LitKind::ByteStr(_) => {
if !*has_errors {
cx.struct_span_err(expr.span, "cannot concatenate doubly nested array")
.note("byte strings are treated as arrays of bytes")
.help("try flattening the array")
.emit();
}
*has_errors = true;
None
}
_ => {
if !*has_errors {
invalid_type_err(cx, expr, true);
}
*has_errors = true;
None
}
},
_ => {
missing_literals.push(expr.span);
None
}
}
}

pub fn expand_concat_bytes(
cx: &mut base::ExtCtxt<'_>,
sp: rustc_span::Span,
Expand All @@ -88,48 +134,27 @@ pub fn expand_concat_bytes(
match e.kind {
ast::ExprKind::Array(ref exprs) => {
for expr in exprs {
match expr.kind {
ast::ExprKind::Array(_) => {
if !has_errors {
cx.span_err(expr.span, "cannot concatenate doubly nested array");
}
has_errors = true;
}
ast::ExprKind::Lit(ref lit) => match lit.kind {
ast::LitKind::Int(
val,
ast::LitIntType::Unsuffixed
| ast::LitIntType::Unsigned(ast::UintTy::U8),
) if val <= u8::MAX.into() => {
accumulator.push(val as u8);
}

ast::LitKind::Byte(val) => {
accumulator.push(val);
}
ast::LitKind::ByteStr(_) => {
if !has_errors {
cx.struct_span_err(
expr.span,
"cannot concatenate doubly nested array",
)
.note("byte strings are treated as arrays of bytes")
.help("try flattening the array")
.emit();
}
has_errors = true;
}
_ => {
if !has_errors {
invalid_type_err(cx, expr, true);
}
has_errors = true;
}
},
_ => {
missing_literals.push(expr.span);
if let Some(elem) =
handle_array_element(cx, &mut has_errors, &mut missing_literals, expr)
{
accumulator.push(elem);
}
}
}
ast::ExprKind::Repeat(ref expr, ref count) => {
if let ast::ExprKind::Lit(ast::Lit {
kind: ast::LitKind::Int(count_val, _), ..
}) = count.value.kind
{
if let Some(elem) =
handle_array_element(cx, &mut has_errors, &mut missing_literals, expr)
{
for _ in 0..count_val {
accumulator.push(elem);
}
}
} else {
cx.span_err(count.value.span, "repeat count is not a number");
}
}
ast::ExprKind::Lit(ref lit) => match lit.kind {
Expand Down
8 changes: 8 additions & 0 deletions src/test/ui/macros/concat-bytes-error.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -39,4 +39,12 @@ fn main() {
]);
concat_bytes!(5u16); //~ ERROR cannot concatenate numeric literals
concat_bytes!([5u16]); //~ ERROR numeric literal is not a `u8`
concat_bytes!([3; ()]); //~ ERROR repeat count is not a number
concat_bytes!([3; -2]); //~ ERROR repeat count is not a number
concat_bytes!([pie; -2]); //~ ERROR repeat count is not a number
concat_bytes!([pie; 2]); //~ ERROR expected a byte literal
concat_bytes!([2.2; 0]); //~ ERROR cannot concatenate float literals
concat_bytes!([5.5; ()]); //~ ERROR repeat count is not a number
concat_bytes!([[1, 2, 3]; 3]); //~ ERROR cannot concatenate doubly nested array
concat_bytes!([[42; 2]; 3]); //~ ERROR cannot concatenate doubly nested array
}
52 changes: 51 additions & 1 deletion src/test/ui/macros/concat-bytes-error.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -127,5 +127,55 @@ error: numeric literal is not a `u8`
LL | concat_bytes!([5u16]);
| ^^^^

error: aborting due to 20 previous errors
error: repeat count is not a number
--> $DIR/concat-bytes-error.rs:42:23
|
LL | concat_bytes!([3; ()]);
| ^^

error: repeat count is not a number
--> $DIR/concat-bytes-error.rs:43:23
|
LL | concat_bytes!([3; -2]);
| ^^

error: repeat count is not a number
--> $DIR/concat-bytes-error.rs:44:25
|
LL | concat_bytes!([pie; -2]);
| ^^

error: expected a byte literal
--> $DIR/concat-bytes-error.rs:45:20
|
LL | concat_bytes!([pie; 2]);
| ^^^
|
= note: only byte literals (like `b"foo"`, `b's'`, and `[3, 4, 5]`) can be passed to `concat_bytes!()`

error: cannot concatenate float literals
--> $DIR/concat-bytes-error.rs:46:20
|
LL | concat_bytes!([2.2; 0]);
| ^^^

error: repeat count is not a number
--> $DIR/concat-bytes-error.rs:47:25
|
LL | concat_bytes!([5.5; ()]);
| ^^

error: cannot concatenate doubly nested array
--> $DIR/concat-bytes-error.rs:48:20
|
LL | concat_bytes!([[1, 2, 3]; 3]);
| ^^^^^^^^^

error: cannot concatenate doubly nested array
--> $DIR/concat-bytes-error.rs:49:20
|
LL | concat_bytes!([[42; 2]; 3]);
| ^^^^^^^

error: aborting due to 28 previous errors

12 changes: 11 additions & 1 deletion src/test/ui/macros/concat-bytes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,5 +3,15 @@

fn main() {
assert_eq!(concat_bytes!(), &[]);
assert_eq!(concat_bytes!(b'A', b"BC", [68, b'E', 70]), b"ABCDEF");
assert_eq!(
concat_bytes!(b'A', b"BC", [68, b'E', 70], [b'G'; 1], [72; 2], [73u8; 3], [65; 0]),
b"ABCDEFGHHIII",
);
assert_eq!(
concat_bytes!(
concat_bytes!(b"AB", b"CD"),
concat_bytes!(b"EF", b"GH"),
),
b"ABCDEFGH",
);
}

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