Fix big integer representation of large numbers such as 98765.0e309

src/check_expr.cpp

@@ -2516,6 +2516,28 @@ gb_internal bool check_representable_as_constant(CheckerContext *c, ExactValue i
 			return false;
 		}
 		check_update_float_precision(&v, type);
+
+		if (in_value.kind == ExactValue_Integer) {
+			bool overflowed = isinf(v.value_float) || isnan(v.value_float);
+			if (!overflowed) {
+				switch (type->Basic.kind) {
+				case Basic_f16:
+				case Basic_f16le:
+				case Basic_f16be:
+					// `check_update_float_precision` only rounds `f16` to `f32` precision, so a value
+					// that is finite as `f32` but out of range for `f16` must be caught explicitly.
+					if (isinf(cast(f64)f16_to_f32(f32_to_f16(cast(f32)v.value_float)))) {
+						overflowed = true;
+					}
+					break;
+				}
+			}
+			if (overflowed) {
+				// Leave `out_value` unset so the diagnostic reports the exact (finite) source value.
+				return false;
+			}
+		}
+
 		if (out_value) *out_value = v;
 
 		switch (type->Basic.kind) {
@@ -12607,6 +12629,10 @@ gb_internal ExprKind check_expr_base_internal(CheckerContext *c, Operand *o, Ast
 			t = t_untyped_integer;
 			if (bl->token.kind == Token_Rune) {
 				t = t_untyped_rune;
+			} else if (string_contains_char(bl->token.string, '.')) {
+				// NOTE(bill): A floating-point literal whose value happens to be an integer (e.g. `98765.0e309`) keeps
+				// its exact value as an integer, but still defaults to untyped float because it was written in floating-point form.
+				t = t_untyped_float;
 			}
 			break;
 		default: