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transpile: Import num_traits::Float for method calls on f128 #1695

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transpile: Import num_traits::Float for method calls on f128 #1695

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34 changes: 27 additions & 7 deletions c2rust-transpile/src/translator/builtins.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -98,15 +98,9 @@ impl<'c> Translation<'c> {
))
}
"__builtin_signbit" | "__builtin_signbitf" | "__builtin_signbitl" => {
// Long doubles require the Float trait from num_traits to call this method
if builtin_name == "__builtin_signbitl" {
self.with_cur_file_item_store(|item_store| {
item_store.add_use(true, vec!["num_traits".into()], "Float");
});
}
self.import_num_traits(args[0])?;

let val = self.convert_expr(ctx.used(), args[0], None)?;

Ok(val.map(|v| {
let val = mk().method_call_expr(v, "is_sign_negative", vec![]);

Expand Down Expand Up @@ -149,10 +143,14 @@ impl<'c> Translation<'c> {
Ok(val.map(|x| mk().method_call_expr(x, "swap_bytes", vec![])))
}
"__builtin_fabs" | "__builtin_fabsf" | "__builtin_fabsl" => {
self.import_num_traits(args[0])?;

let val = self.convert_expr(ctx.used(), args[0], None)?;
Ok(val.map(|x| mk().method_call_expr(x, "abs", vec![])))
}
"__builtin_isfinite" | "__builtin_isnan" => {
self.import_num_traits(args[0])?;

let val = self.convert_expr(ctx.used(), args[0], None)?;

let seg = match builtin_name {
Expand All @@ -166,6 +164,8 @@ impl<'c> Translation<'c> {
}))
}
"__builtin_isinf_sign" => {
self.import_num_traits(args[0])?;

// isinf_sign(x) -> fabs(x) == infinity ? (signbit(x) ? -1 : 1) : 0
let val = self.convert_expr(ctx.used(), args[0], None)?;
Ok(val.map(|x| {
Expand Down Expand Up @@ -723,6 +723,26 @@ impl<'c> Translation<'c> {
}
}

fn import_num_traits(&self, arg_id: CExprId) -> TranslationResult<()> {
let arg_type_id = self.ast_context[arg_id]
.kind
.get_qual_type()
.ok_or_else(|| format_err!("bad arg type"))?;
let arg_type_kind = &self.ast_context.resolve_type(arg_type_id.ctype).kind;

match arg_type_kind {
CTypeKind::LongDouble | CTypeKind::Float128 => {
self.use_crate(ExternCrate::NumTraits);
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@ahomescu ahomescu Mar 26, 2026

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Was this not needed before because there's a cast after? Or how did this work before?

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@Rua Rua Mar 26, 2026 •
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I'm not sure it ever worked. These methods are not inherent methods of f128, they are provided by the Float trait. So without importing that, you just get a compile error.

self.with_cur_file_item_store(|item_store| {
item_store.add_use(true, vec!["num_traits".into()], "Float");
});
}
_ => {}
}

Ok(())
}

// This translation logic handles converting code that uses
// https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html
fn convert_overflow_arith(
Expand Down
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