From 6467ef6d3b5648d47c13b877d3d4fe6a5b5efb7d Mon Sep 17 00:00:00 2001
From: jacob gw <jacoblevgw@gmail.com>
Date: Mon, 1 Mar 2021 11:25:50 -0500
Subject: [PATCH] cbe: add error comparison support

---
 src/codegen.zig     |  2 ++
 src/type.zig        |  2 +-
 src/zir_sema.zig    |  3 ++-
 test/stage2/cbe.zig | 56 +++++++++++++++++++++++++++++----------------
 4 files changed, 41 insertions(+), 22 deletions(-)

diff --git a/src/codegen.zig b/src/codegen.zig
index c3cd64cf73..cfe605b567 100644
--- a/src/codegen.zig
+++ b/src/codegen.zig
@@ -2237,6 +2237,8 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
             // No side effects, so if it's unreferenced, do nothing.
             if (inst.base.isUnused())
                 return MCValue{ .dead = {} };
+            if (inst.lhs.ty.zigTypeTag() == .ErrorSet or inst.rhs.ty.zigTypeTag() == .ErrorSet)
+                return self.fail(inst.base.src, "TODO implement cmp for errors", .{});
             switch (arch) {
                 .x86_64 => {
                     try self.code.ensureCapacity(self.code.items.len + 8);
diff --git a/src/type.zig b/src/type.zig
index 50d55a0c54..c3a99bb184 100644
--- a/src/type.zig
+++ b/src/type.zig
@@ -1663,6 +1663,7 @@ pub const Type = extern union {
             .Int,
             .Float,
             .ErrorSet,
+            .ErrorUnion,
             .Enum,
             .Frame,
             .AnyFrame,
@@ -1687,7 +1688,6 @@ pub const Type = extern union {
             },
             .Pointer, .Array => ty = ty.elemType(),
 
-            .ErrorUnion => @panic("TODO fn isValidVarType"),
             .Fn => @panic("TODO fn isValidVarType"),
             .Struct => @panic("TODO struct isValidVarType"),
             .Union => @panic("TODO union isValidVarType"),
diff --git a/src/zir_sema.zig b/src/zir_sema.zig
index 9cbdfd07dd..a1b79879b8 100644
--- a/src/zir_sema.zig
+++ b/src/zir_sema.zig
@@ -2326,7 +2326,8 @@ fn zirCmp(
                 return mod.constBool(scope, inst.base.src, std.mem.eql(u8, lval.castTag(.@"error").?.data.name, rval.castTag(.@"error").?.data.name) == (op == .eq));
             }
         }
-        return mod.fail(scope, inst.base.src, "TODO implement equality comparison between runtime errors", .{});
+        const b = try mod.requireRuntimeBlock(scope, inst.base.src);
+        return mod.addBinOp(b, inst.base.src, Type.initTag(.bool), if (op == .eq) .cmp_eq else .cmp_neq, lhs, rhs);
     } else if (lhs.ty.isNumeric() and rhs.ty.isNumeric()) {
         // This operation allows any combination of integer and float types, regardless of the
         // signed-ness, comptime-ness, and bit-width. So peer type resolution is incorrect for
diff --git a/test/stage2/cbe.zig b/test/stage2/cbe.zig
index ba679f49a0..1487b15e12 100644
--- a/test/stage2/cbe.zig
+++ b/test/stage2/cbe.zig
@@ -244,30 +244,46 @@ pub fn addCases(ctx: *TestContext) !void {
             \\}
         , "");
     }
+    //{
+    //    var case = ctx.exeFromCompiledC("optionals", .{});
+
+    //    // Simple while loop
+    //    case.addCompareOutput(
+    //        \\export fn main() c_int {
+    //        \\    var count: c_int = 0;
+    //        \\    var opt_ptr: ?*c_int = &count;
+    //        \\    while (opt_ptr) |_| : (count += 1) {
+    //        \\        if (count == 4) opt_ptr = null;
+    //        \\    }
+    //        \\    return count - 5;
+    //        \\}
+    //    , "");
+
+    //    // Same with non pointer optionals
+    //    case.addCompareOutput(
+    //        \\export fn main() c_int {
+    //        \\    var count: c_int = 0;
+    //        \\    var opt_ptr: ?c_int = count;
+    //        \\    while (opt_ptr) |_| : (count += 1) {
+    //        \\        if (count == 4) opt_ptr = null;
+    //        \\    }
+    //        \\    return count - 5;
+    //        \\}
+    //    , "");
+    //}
     {
-        var case = ctx.exeFromCompiledC("optionals", .{});
-
-        // Simple while loop
+        var case = ctx.exeFromCompiledC("errors", .{});
         case.addCompareOutput(
             \\export fn main() c_int {
-            \\    var count: c_int = 0;
-            \\    var opt_ptr: ?*c_int = &count;
-            \\    while (opt_ptr) |_| : (count += 1) {
-            \\        if (count == 4) opt_ptr = null;
-            \\    }
-            \\    return count - 5;
+            \\    var e1 = error.Foo;
+            \\    var e2 = error.Bar;
+            \\    assert(e1 != e2);
+            \\    assert(e1 == error.Foo);
+            \\    assert(e2 == error.Bar);
+            \\    return 0;
             \\}
-        , "");
-
-        // Same with non pointer optionals
-        case.addCompareOutput(
-            \\export fn main() c_int {
-            \\    var count: c_int = 0;
-            \\    var opt_ptr: ?c_int = count;
-            \\    while (opt_ptr) |_| : (count += 1) {
-            \\        if (count == 4) opt_ptr = null;
-            \\    }
-            \\    return count - 5;
+            \\fn assert(b: bool) void {
+            \\    if (!b) unreachable;
             \\}
         , "");
     }