add compile error for shifting by negative comptime integer

closes #698
ziglang · Jan 18, 2018 · 4b64c77 · 4b64c77
1 parent 0fc645a
commit 4b64c77
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Showing 2 changed files with 14 additions and 1 deletion.
diff --git a/src/ir.cpp b/src/ir.cpp
@@ -8816,6 +8816,13 @@ static TypeTableEntry *ir_analyze_bit_shift(IrAnalyze *ira, IrInstructionBinOp *
         if (op_id == IrBinOpBitShiftLeftLossy) {
             op_id = IrBinOpBitShiftLeftExact;
         }
+
+        if (casted_op2->value.data.x_bigint.is_negative) {
+            Buf *val_buf = buf_alloc();
+            bigint_append_buf(val_buf, &casted_op2->value.data.x_bigint, 10);
+            ir_add_error(ira, casted_op2, buf_sprintf("shift by negative value %s", buf_ptr(val_buf)));
+            return ira->codegen->builtin_types.entry_invalid;
+        }
     } else {
         TypeTableEntry *shift_amt_type = get_smallest_unsigned_int_type(ira->codegen,
                 op1->value.type->data.integral.bit_count - 1);

diff --git a/test/compile_errors.zig b/test/compile_errors.zig
@@ -1,13 +1,19 @@
 const tests = @import("tests.zig");
 
 pub fn addCases(cases: &tests.CompileErrorContext) {
+    cases.add("shift by negative comptime integer",
+        \\comptime {
+        \\    var a = 1 >> -1;
+        \\}
+    , ".tmp_source.zig:2:18: error: shift by negative value -1");
+
     cases.add("@panic called at compile time",
         \\export fn entry() {
         \\    comptime {
         \\        @panic("aoeu");
         \\    }
         \\}
-    , "error: encountered @panic at compile-time");
+    , ".tmp_source.zig:3:9: error: encountered @panic at compile-time");
 
     cases.add("wrong return type for main",
         \\pub fn main() -> f32 { }