From fad95741db7529bbad873fb330c25d64ac765340 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Wed, 13 Jul 2022 15:59:46 -0700
Subject: [PATCH] AstGen: fix loop control flow applying to wrong loop

In the case of 'continue' or 'break' inside the 'else' block of a
'while' or 'for' loop.

Closes #12109
---
 lib/std/net/test.zig    |  1 -
 lib/std/os.zig          |  6 +++---
 src/AstGen.zig          |  8 ++++++++
 test/behavior/for.zig   | 14 ++++++++++++++
 test/behavior/while.zig | 10 ++++++++++
 5 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/lib/std/net/test.zig b/lib/std/net/test.zig
index 5d350be7e0..f2946777bd 100644
--- a/lib/std/net/test.zig
+++ b/lib/std/net/test.zig
@@ -104,7 +104,6 @@ test "parse and render UNIX addresses" {
 }
 
 test "resolve DNS" {
-    if (@import("builtin").zig_backend != .stage1) return error.SkipZigTest;
     if (builtin.os.tag == .wasi) return error.SkipZigTest;
 
     if (builtin.os.tag == .windows) {
diff --git a/lib/std/os.zig b/lib/std/os.zig
index 02ed710dd3..f4653920ae 100644
--- a/lib/std/os.zig
+++ b/lib/std/os.zig
@@ -6476,7 +6476,7 @@ pub fn dn_expand(
             p = msg.ptr + j;
         } else if (p[0] != 0) {
             if (dest != exp_dn.ptr) {
-                dest.* = '.';
+                dest[0] = '.';
                 dest += 1;
             }
             var j = p[0];
@@ -6486,12 +6486,12 @@ pub fn dn_expand(
             }
             while (j != 0) {
                 j -= 1;
-                dest.* = p[0];
+                dest[0] = p[0];
                 dest += 1;
                 p += 1;
             }
         } else {
-            dest.* = 0;
+            dest[0] = 0;
             if (len == std.math.maxInt(usize)) len = @ptrToInt(p) + 1 - @ptrToInt(comp_dn.ptr);
             return len;
         }
diff --git a/src/AstGen.zig b/src/AstGen.zig
index 7220fe758d..252610aeeb 100644
--- a/src/AstGen.zig
+++ b/src/AstGen.zig
@@ -5795,6 +5795,10 @@ fn whileExpr(
                 break :s &else_scope.base;
             }
         };
+        // Remove the continue block and break block so that `continue` and `break`
+        // control flow apply to outer loops; not this one.
+        loop_scope.continue_block = 0;
+        loop_scope.break_block = 0;
         const e = try expr(&else_scope, sub_scope, loop_scope.break_result_loc, else_node);
         if (!else_scope.endsWithNoReturn()) {
             loop_scope.break_count += 1;
@@ -5994,6 +5998,10 @@ fn forExpr(
         result: Zir.Inst.Ref,
     } = if (else_node != 0) blk: {
         const sub_scope = &else_scope.base;
+        // Remove the continue block and break block so that `continue` and `break`
+        // control flow apply to outer loops; not this one.
+        loop_scope.continue_block = 0;
+        loop_scope.break_block = 0;
         const else_result = try expr(&else_scope, sub_scope, loop_scope.break_result_loc, else_node);
         if (!else_scope.endsWithNoReturn()) {
             loop_scope.break_count += 1;
diff --git a/test/behavior/for.zig b/test/behavior/for.zig
index 5188f02381..da6f0717ae 100644
--- a/test/behavior/for.zig
+++ b/test/behavior/for.zig
@@ -210,3 +210,17 @@ test "for on slice with allowzero ptr" {
     try S.doTheTest(&[_]u8{ 1, 2, 3, 4 });
     comptime try S.doTheTest(&[_]u8{ 1, 2, 3, 4 });
 }
+
+test "else continue outer for" {
+    if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
+    if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
+
+    var i: usize = 6;
+    var buf: [5]u8 = undefined;
+    while (true) {
+        i -= 1;
+        for (buf[i..5]) |_| {
+            return;
+        } else continue;
+    }
+}
diff --git a/test/behavior/while.zig b/test/behavior/while.zig
index b664e73b89..62d5bf90fa 100644
--- a/test/behavior/while.zig
+++ b/test/behavior/while.zig
@@ -334,3 +334,13 @@ test "continue inline while loop" {
     }
     comptime assert(i == 5);
 }
+
+test "else continue outer while" {
+    var i: usize = 0;
+    while (true) {
+        i += 1;
+        while (i > 5) {
+            return;
+        } else continue;
+    }
+}