Teach rustc to add istrs. Issue #855

src/comp/middle/trans_ivec.rs

@@ -494,6 +494,16 @@ fn trans_add(cx: &@block_ctxt, vec_ty: ty::t, lhs: ValueRef,
     let lhs_len = lhs_len_and_data.len;
     let lhs_data = lhs_len_and_data.data;
     bcx = lhs_len_and_data.bcx;
+
+    lhs_len = alt ty::struct(bcx_tcx(bcx), vec_ty) {
+      ty::ty_istr. {
+        // Forget about the trailing null on the left side
+        bcx.build.Sub(lhs_len, C_uint(1u))
+      }
+      ty::ty_vec(_) { lhs_len }
+      _ { bcx_tcx(bcx).sess.bug("non-istr/ivec in trans_add") }
+    };
+
     let rhs_len_and_data = get_len_and_data(bcx, rhs, unit_ty);
     let rhs_len = rhs_len_and_data.len;
     let rhs_data = rhs_len_and_data.data;

src/test/run-pass/istr.rs

@@ -12,8 +12,11 @@ fn test_heap_lit() {
 }
 
 fn test_heap_assign() {
-    let s: istr;
-    s = ~"AAAA";
+    let s: istr = ~"a big ol' string";
+    let t: istr = ~"a big ol' string";
+    assert s == t;
+    let u: istr = ~"a bad ol' string";
+    assert s != u;
 }
 
 fn test_heap_log() {
@@ -21,9 +24,27 @@ fn test_heap_log() {
     log s;
 }
 
+fn test_stack_add() {
+    assert ~"a" + ~"b" == ~"ab";
+    let s: istr = ~"a";
+    assert s + s == ~"aa";
+    assert ~"" + ~"" == ~"";
+}
+
+fn test_stack_heap_add() {
+    assert ~"a" + ~"bracadabra" == ~"abracadabra";
+}
+
+fn test_heap_add() {
+    assert ~"this should" + ~" totally work" == ~"this should totally work";
+}
+
 fn main() {
     test_stack_assign();
     test_heap_lit();
     test_heap_assign();
     test_heap_log();
+    test_stack_add();
+    test_stack_heap_add();
+    test_heap_add();
 }