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Respect the f32 and f64 suffix on literals #126

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Merged
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Jan 8, 2021
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Respect the f32 and f64 suffix on literals #126

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4 changes: 0 additions & 4 deletions gcc/rust/backend/rust-compile-expr.h
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Original file line number Diff line number Diff line change
Expand Up @@ -156,8 +156,6 @@ class CompileExpr : public HIRCompileBase
return;

case HIR::Literal::FLOAT: {
printf ("FLOATY BOYO: [%s]\n", expr.as_string ().c_str ());

mpfr_t fval;
if (mpfr_init_set_str (fval, expr.as_string ().c_str (), 10,
MPFR_RNDN)
Expand All @@ -177,8 +175,6 @@ class CompileExpr : public HIRCompileBase
return;
}

printf ("tyty float is [%s]\n", tyty->as_string ().c_str ());

Btype *type = TyTyResolveCompile::compile (ctx, tyty);
translated
= ctx->get_backend ()->float_constant_expression (type, fval);
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2 changes: 2 additions & 0 deletions gcc/rust/hir/tree/rust-hir.h
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Original file line number Diff line number Diff line change
Expand Up @@ -257,6 +257,8 @@ struct Literal
return Literal ("", CHAR, PrimitiveCoreType::CORETYPE_UNKNOWN);
}

void set_lit_type (LitType lt) { type = lt; }

// Returns whether literal is in an invalid state.
bool is_error () const { return value_as_string == ""; }
};
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10 changes: 0 additions & 10 deletions gcc/rust/lex/rust-lex.cc
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Expand Up @@ -1938,16 +1938,6 @@ Lexer::parse_decimal_int_or_float (Location loc)
PrimitiveCoreType type_hint = type_suffix_pair.first;
length += type_suffix_pair.second;

if (type_hint == CORETYPE_F32 || type_hint == CORETYPE_F64)
{
rust_error_at (
get_current_location (),
"invalid type suffix %qs for integer (decimal) literal",
get_type_hint_string (type_hint));
// ignore invalid type suffix as everything else seems fine
type_hint = CORETYPE_UNKNOWN;
}

current_column += length;

str.shrink_to_fit ();
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The code below here (the make_int) would be incorrect (assuming that an integer with a type hint of a float type is treated as a float). What should happen instead is that make_float is called if the type hint is 'f32' or 'f64', while 'make_int' should be called otherwise. This is assuming that I have understood the spec properly.

I suppose it depends on whether rust is actually permissive on integers being marked as floats (i.e. allows integers to be given a float type hint) or whether the float type hint means that the integer is treated as a float.

If my interpretation is wrong, feel free to ignore this.

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Yeah this was not clear from the spec to me either. From testing the rust compiler i found this is permissive:

fn main() {
    let a: i32 = 5i32;
    let b: f32 = 5f32;
}

Without this change we determine:

float1.rs:3:18: error: invalid type suffix ‘f32’ for integer (decimal) literal
    3 |     let b: f32 = 5f32;
      |

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What if i split this change into two parts one where we support f32 and f64 suffix but remove this integer support for float suffix as a separate PR

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Yeah this was not clear from the spec to me either.

It may be a good idea to document this kind of things in the reference (https://github.com/rust-lang/reference/), so other alternative implementations don't have to discover it again.

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I've created rust-lang/reference#922

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25 changes: 23 additions & 2 deletions gcc/rust/typecheck/rust-hir-type-check-expr.h
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Expand Up @@ -188,6 +188,15 @@ class TypeCheckExpr : public TypeCheckBase
ok = context->lookup_builtin ("u128", &infered);
break;

case CORETYPE_F32:
expr.get_literal ()->set_lit_type (HIR::Literal::LitType::FLOAT);
ok = context->lookup_builtin ("f32", &infered);
break;
case CORETYPE_F64:
expr.get_literal ()->set_lit_type (HIR::Literal::LitType::FLOAT);
ok = context->lookup_builtin ("f64", &infered);
break;

default:
ok = context->lookup_builtin ("i32", &infered);
break;
Expand All @@ -197,8 +206,20 @@ class TypeCheckExpr : public TypeCheckBase
break;

case HIR::Literal::LitType::FLOAT: {
// FIXME need to respect the suffix if applicable
auto ok = context->lookup_builtin ("f32", &infered);
bool ok = false;

switch (expr.get_literal ()->get_type_hint ())
{
case CORETYPE_F32:
ok = context->lookup_builtin ("f32", &infered);
break;
case CORETYPE_F64:
ok = context->lookup_builtin ("f64", &infered);
break;
default:
ok = context->lookup_builtin ("f32", &infered);
break;
}
rust_assert (ok);
}
break;
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11 changes: 11 additions & 0 deletions gcc/testsuite/rust.test/compilable/float_types.rs
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@@ -0,0 +1,11 @@
fn main() {
let a1: f32 = 1.0f32;
let a2: f64 = 2.0f64;
let a3: f32 = 3f32;
let a4: f64 = 4f64;

let b1 = 1.0f32;
let b2 = 2.0f64;
let b3 = 3f32;
let b4 = 4f64;
}