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Enforce the static symbol order. #74203

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Merged
merged 2 commits into from
Jul 16, 2020
Merged

Enforce the static symbol order. #74203

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fd8f177
Enforce the static symbol order.
nnethercote Jul 9, 2020
600b824
Rename `sym::item_context` as `sym::ItemContext`.
nnethercote Jul 10, 2020
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29 changes: 24 additions & 5 deletions src/librustc_macros/src/symbols.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -87,18 +87,29 @@ pub fn symbols(input: TokenStream) -> TokenStream {
let mut prefill_stream = quote! {};
let mut counter = 0u32;
let mut keys = HashSet::<String>::new();
let mut prev_key: Option<String> = None;
let mut errors = Vec::<String>::new();

let mut check_dup = |str: &str| {
let mut check_dup = |str: &str, errors: &mut Vec<String>| {
if !keys.insert(str.to_string()) {
panic!("Symbol `{}` is duplicated", str);
errors.push(format!("Symbol `{}` is duplicated", str));
}
};

let mut check_order = |str: &str, errors: &mut Vec<String>| {
if let Some(ref prev_str) = prev_key {
if str < prev_str {
errors.push(format!("Symbol `{}` must precede `{}`", str, prev_str));
}
}
prev_key = Some(str.to_string());
};

// Generate the listed keywords.
for keyword in &input.keywords.0 {
let name = &keyword.name;
let value = &keyword.value;
check_dup(&value.value());
check_dup(&value.value(), &mut errors);
prefill_stream.extend(quote! {
#value,
});
Expand All @@ -116,7 +127,8 @@ pub fn symbols(input: TokenStream) -> TokenStream {
Some(value) => value.value(),
None => name.to_string(),
};
check_dup(&value);
check_dup(&value, &mut errors);
check_order(&name.to_string(), &mut errors);
prefill_stream.extend(quote! {
#value,
});
Expand All @@ -131,7 +143,7 @@ pub fn symbols(input: TokenStream) -> TokenStream {
// Generate symbols for the strings "0", "1", ..., "9".
for n in 0..10 {
let n = n.to_string();
check_dup(&n);
check_dup(&n, &mut errors);
prefill_stream.extend(quote! {
#n,
});
Expand All @@ -141,6 +153,13 @@ pub fn symbols(input: TokenStream) -> TokenStream {
counter += 1;
}

if !errors.is_empty() {
for error in errors.into_iter() {
eprintln!("error: {}", error)
}
panic!("errors in `Keywords` and/or `Symbols`");
}

let tt = TokenStream::from(quote! {
macro_rules! keywords {
() => {
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