if expressions

src/comp/middle/trans.rs

@@ -3021,21 +3021,36 @@ fn trans_if(@block_ctxt cx, @ast.expr cond,
     auto then_res = trans_block(then_cx, thn);
 
     auto else_cx = new_scope_block_ctxt(cx, "else");
-    auto else_res = res(else_cx, C_nil());
 
+    auto else_res;
+    auto expr_llty;
     alt (els) {
         case (some[@ast.expr](?elexpr)) {
             else_res = trans_expr(else_cx, elexpr);
+
+            // If we have an else expression, then the entire
+            // if expression can have a non-nil type.
+            auto expr_ty = ty.expr_ty(elexpr);
+            if (ty.type_has_dynamic_size(expr_ty)) {
+                expr_llty = T_typaram_ptr(cx.fcx.ccx.tn);
+            } else {
+                expr_llty = type_of(else_res.bcx.fcx.ccx, expr_ty);
+                if (ty.type_is_structural(expr_ty)) {
+                    expr_llty = T_ptr(expr_llty);
+                }
+            }
+        }
+        case (_) {
+            else_res = res(else_cx, C_nil());
+            expr_llty = T_nil();
         }
-        case (_) { /* fall through */ }
     }
 
     cond_res.bcx.build.CondBr(cond_res.val,
                               then_cx.llbb,
                               else_cx.llbb);
 
-    // FIXME: use inferred type when available.
-    ret join_results(cx, T_nil(),
+    ret join_results(cx, expr_llty,
                      vec(then_res, else_res));
 }
 

src/test/run-pass/expr-if-box.rs

@@ -0,0 +1,14 @@
+// xfail-boot
+// xfail-stage0
+// -*- rust -*-
+
+// Tests for if as expressions returning boxed types
+
+fn test_box() {
+  auto res = if (true) { @100 } else { @101 };
+  check (*res == 100);
+}
+
+fn main() {
+  test_box();
+}

src/test/run-pass/expr-if-generic.rs

@@ -0,0 +1,53 @@
+// xfail-boot
+// xfail-stage0
+// -*- rust -*-
+
+// Tests for if as expressions with dynamic type sizes
+
+type compare[T] = fn(&T t1, &T t2) -> bool;
+
+fn test_generic[T](&T expected, &T not_expected, &compare[T] eq) {
+  let T actual = if (true) { expected } else { not_expected };
+  check (eq(expected, actual));
+}
+
+fn test_bool() {
+  fn compare_bool(&bool b1, &bool b2) -> bool {
+    ret b1 == b2;
+  }
+  auto eq = bind compare_bool(_, _);
+  test_generic[bool](true, false, eq);
+}
+
+fn test_tup() {
+  type t = tup(int, int);
+  fn compare_tup(&t t1, &t t2) -> bool {
+    ret t1 == t2;
+  }
+  auto eq = bind compare_tup(_, _);
+  test_generic[t](tup(1, 2), tup(2, 3), eq);
+}
+
+fn test_vec() {
+  fn compare_vec(&vec[int] v1, &vec[int] v2) -> bool {
+    ret v1 == v2;
+  }
+  auto eq = bind compare_vec(_, _);
+  test_generic[vec[int]](vec(1, 2), vec(2, 3), eq);
+}
+
+fn test_box() {
+  fn compare_box(&@bool b1, &@bool b2) -> bool {
+    ret *b1 == *b2;
+  }
+  auto eq = bind compare_box(_, _);
+  test_generic[@bool](@true, @false, eq);
+}
+
+fn main() {
+  test_bool();
+  test_tup();
+  // FIXME: These two don't pass yet
+  test_vec();
+  test_box();
+}

src/test/run-pass/expr-if-struct.rs

@@ -0,0 +1,24 @@
+// xfail-boot
+// -*- rust -*-
+
+// Tests for if as expressions returning structural types
+
+fn test_rec() {
+  auto res = if (true) { rec(i = 100) } else { rec(i = 101) };
+  check (res == rec(i = 100));
+}
+
+fn test_tag() {
+  tag mood {
+    happy;
+    sad;
+  }
+
+  auto res = if (true) { happy } else { sad };
+  check (res == happy);
+}
+
+fn main() {
+  test_rec();
+  test_tag();
+}

src/test/run-pass/expr-if.rs

@@ -0,0 +1,98 @@
+// xfail-boot
+// -*- rust -*-
+
+// Tests for if as expressions
+
+fn test_if() {
+  let bool res = if (true) { true } else { false };
+  check (res);
+}
+
+fn test_else() {
+  let bool res = if (false) { false } else { true };
+  check (res);
+}
+
+fn test_elseif1() {
+  let bool res = if (true) {
+    true
+  } else if (true) {
+    false
+  } else {
+    false
+  };
+  check (res);
+}
+
+fn test_elseif2() {
+  let bool res = if (false) {
+    false
+  } else if (true) {
+    true
+  } else {
+    false
+  };
+  check (res);
+}
+
+fn test_elseif3() {
+  let bool res = if (false) {
+    false
+  } else if (false) {
+    false
+  } else {
+    true
+  };
+  check (res);
+}
+
+fn test_inferrence() {
+  auto res = if (true) { true } else { false };
+  check (res);
+}
+
+fn test_if_as_if_condition() {
+  auto res1 = if (if (false) { false } else { true }) {
+    true
+  } else {
+    false
+  };
+  check (res1);
+
+  auto res2 = if (if (true) { false } else { true }) {
+    false
+  } else {
+    true
+  };
+  check (res2);
+}
+
+fn test_if_as_block_result() {
+  auto res = if (true) {
+    if (false) {
+      false
+    } else {
+      true
+    }
+  } else {
+    false
+  };
+  check (res);
+}
+
+fn test_str() {
+  auto res = if (true) { "happy" } else { "sad" };
+  check (res == "happy");
+}
+
+fn main() {
+  test_if();
+  test_else();
+  test_elseif1();
+  test_elseif2();
+  test_elseif3();
+  test_inferrence();
+  test_if_as_if_condition();
+  test_if_as_block_result();
+  test_str();
+}