Add range lint for float literals, fixing #10934

Author: hirschenberger

src/libcore/num/f32.rs

@@ -11,6 +11,8 @@
 //! Operations and constants for 32-bits floats (`f32` type)
 
 #![doc(primitive = "f32")]
+// FIXME: MIN_VALUE and MAX_VALUE literals are parsed as -inf and inf #14353
+#![allow(type_overflow)]
 
 use intrinsics;
 use mem;

src/libcore/num/f64.rs

@@ -11,6 +11,8 @@
 //! Operations and constants for 64-bits floats (`f64` type)
 
 #![doc(primitive = "f64")]
+// FIXME: MIN_VALUE and MAX_VALUE literals are parsed as -inf and inf #14353
+#![allow(type_overflow)]
 
 use intrinsics;
 use mem;

src/librustc/lint/builtin.rs

@@ -37,14 +37,7 @@ use lint::{Context, LintPass, LintArray};
 
 use std::cmp;
 use std::collections::HashMap;
-use std::i16;
-use std::i32;
-use std::i64;
-use std::i8;
-use std::u16;
-use std::u32;
-use std::u64;
-use std::u8;
+use std::{i8, i16, i32, i64, u8, u16, u32, u64, f32, f64};
 use std::gc::Gc;
 use syntax::abi;
 use syntax::ast_map;
@@ -214,7 +207,21 @@ impl LintPass for TypeLimits {
                                          "literal out of range for its type");
                         }
                     },
-
+                    ty::ty_float(t) => {
+                        let (min, max) = float_ty_range(t);
+                        let lit_val: f64 = match lit.node {
+                            ast::LitFloat(ref v, _) |
+                            ast::LitFloatUnsuffixed(ref v) => match from_str(v.get()) {
+                                Some(f) => f,
+                                None => return
+                            },
+                            _ => fail!()
+                        };
+                        if lit_val < min || lit_val > max {
+                            cx.span_lint(TYPE_OVERFLOW, e.span,
+                                         "literal out of range for its type");
+                        }
+                    },
                     _ => ()
                 };
             },
@@ -265,6 +272,13 @@ impl LintPass for TypeLimits {
             }
         }
 
+        fn float_ty_range(float_ty: ast::FloatTy) -> (f64, f64) {
+            match float_ty {
+                ast::TyF32  => (f32::MIN_VALUE as f64, f32::MAX_VALUE as f64),
+                ast::TyF64  => (f64::MIN_VALUE,        f64::MAX_VALUE)
+            }
+        }
+
         fn check_limits(tcx: &ty::ctxt, binop: ast::BinOp,
                         l: &ast::Expr, r: &ast::Expr) -> bool {
             let (lit, expr, swap) = match (&l.node, &r.node) {

src/test/compile-fail/lint-type-overflow.rs

@@ -47,4 +47,9 @@ fn main() {
     let x = -2147483648_i32; // should be OK
     let x: i32 = -2147483649; //~ error: literal out of range for its type
     let x = -2147483649_i32; //~ error: literal out of range for its type
+
+    let x = -3.40282348e+38_f32; //~ error: literal out of range for its type
+    let x =  3.40282348e+38_f32; //~ error: literal out of range for its type
+    let x = -1.7976931348623159e+308_f64; //~ error: literal out of range for its type
+    let x =  1.7976931348623159e+308_f64; //~ error: literal out of range for its type
 }