From 1563ea9f278e1e1cd0d21fe8c4fc761805b71964 Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Tue, 8 Apr 2014 15:39:46 -0700
Subject: [PATCH] rustc: Remove f{32,64} % from the language

This commit removes the compiler support for floating point modulus operations,
as well as from the language. An implementation for this operator is now
required to be provided by libraries.

Floating point modulus is rarely used, doesn't exist in C, and is always lowered
to an fmod library call by LLVM, and LLVM is considering removing support
entirely.

Closes #12278
---
 src/librustc/middle/ty.rs | 19 ++++++++++---------
 src/libstd/num/f32.rs     |  5 ++++-
 src/libstd/num/f64.rs     |  5 ++++-
 3 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/src/librustc/middle/ty.rs b/src/librustc/middle/ty.rs
index a250c6c298b..fb48fded2a5 100644
--- a/src/librustc/middle/ty.rs
+++ b/src/librustc/middle/ty.rs
@@ -4125,6 +4125,7 @@ pub fn is_binopable(cx: &ctxt, ty: t, op: ast::BinOp) -> bool {
     static opcat_eq: int = 5;
     static opcat_bit: int = 6;
     static opcat_logic: int = 7;
+    static opcat_mod: int = 8;
 
     fn opcat(op: ast::BinOp) -> int {
         match op {
@@ -4132,7 +4133,7 @@ pub fn is_binopable(cx: &ctxt, ty: t, op: ast::BinOp) -> bool {
           ast::BiSub => opcat_sub,
           ast::BiMul => opcat_mult,
           ast::BiDiv => opcat_mult,
-          ast::BiRem => opcat_mult,
+          ast::BiRem => opcat_mod,
           ast::BiAnd => opcat_logic,
           ast::BiOr => opcat_logic,
           ast::BiBitXor => opcat_bit,
@@ -4168,14 +4169,14 @@ pub fn is_binopable(cx: &ctxt, ty: t, op: ast::BinOp) -> bool {
     static f: bool = false;
 
     let tbl = [
-    //           +, -, *, shift, rel, ==, bit, logic
-    /*other*/   [f, f, f, f,     f,   f,  f,   f],
-    /*bool*/    [f, f, f, f,     t,   t,  t,   t],
-    /*char*/    [f, f, f, f,     t,   t,  f,   f],
-    /*int*/     [t, t, t, t,     t,   t,  t,   f],
-    /*float*/   [t, t, t, f,     t,   t,  f,   f],
-    /*bot*/     [t, t, t, t,     t,   t,  t,   t],
-    /*raw ptr*/ [f, f, f, f,     t,   t,  f,   f]];
+    //           +, -, *, shift, rel, ==, bit, logic, mod
+    /*other*/   [f, f, f, f,     f,   f,  f,   f,     f],
+    /*bool*/    [f, f, f, f,     t,   t,  t,   t,     f],
+    /*char*/    [f, f, f, f,     t,   t,  f,   f,     f],
+    /*int*/     [t, t, t, t,     t,   t,  t,   f,     t],
+    /*float*/   [t, t, t, f,     t,   t,  f,   f,     f],
+    /*bot*/     [t, t, t, t,     t,   t,  t,   t,     t],
+    /*raw ptr*/ [f, f, f, f,     t,   t,  f,   f,     f]];
 
     return tbl[tycat(cx, ty) as uint ][opcat(op) as uint];
 }
diff --git a/src/libstd/num/f32.rs b/src/libstd/num/f32.rs
index 7c5fe4ff274..cf457763513 100644
--- a/src/libstd/num/f32.rs
+++ b/src/libstd/num/f32.rs
@@ -41,6 +41,7 @@ mod cmath {
         pub fn frexpf(n: c_float, value: &mut c_int) -> c_float;
         pub fn fmaxf(a: c_float, b: c_float) -> c_float;
         pub fn fminf(a: c_float, b: c_float) -> c_float;
+        pub fn fmodf(a: c_float, b: c_float) -> c_float;
         pub fn nextafterf(x: c_float, y: c_float) -> c_float;
         pub fn hypotf(x: c_float, y: c_float) -> c_float;
         pub fn ldexpf(x: c_float, n: c_int) -> c_float;
@@ -201,7 +202,9 @@ impl Div<f32,f32> for f32 {
 #[cfg(not(test))]
 impl Rem<f32,f32> for f32 {
     #[inline]
-    fn rem(&self, other: &f32) -> f32 { *self % *other }
+    fn rem(&self, other: &f32) -> f32 {
+        unsafe { cmath::fmodf(*self, *other) }
+    }
 }
 
 #[cfg(not(test))]
diff --git a/src/libstd/num/f64.rs b/src/libstd/num/f64.rs
index 69328a5ecdc..4a751988d36 100644
--- a/src/libstd/num/f64.rs
+++ b/src/libstd/num/f64.rs
@@ -40,6 +40,7 @@ mod cmath {
         pub fn fdim(a: c_double, b: c_double) -> c_double;
         pub fn fmax(a: c_double, b: c_double) -> c_double;
         pub fn fmin(a: c_double, b: c_double) -> c_double;
+        pub fn fmod(a: c_double, b: c_double) -> c_double;
         pub fn nextafter(x: c_double, y: c_double) -> c_double;
         pub fn frexp(n: c_double, value: &mut c_int) -> c_double;
         pub fn hypot(x: c_double, y: c_double) -> c_double;
@@ -210,7 +211,9 @@ impl Div<f64,f64> for f64 {
 #[cfg(not(test))]
 impl Rem<f64,f64> for f64 {
     #[inline]
-    fn rem(&self, other: &f64) -> f64 { *self % *other }
+    fn rem(&self, other: &f64) -> f64 {
+        unsafe { cmath::fmod(*self, *other) }
+    }
 }
 #[cfg(not(test))]
 impl Neg<f64> for f64 {