From 20d0018d79c25a0def440040eab2970e7a314130 Mon Sep 17 00:00:00 2001
From: Veikka Tuominen <git@vexu.eu>
Date: Sun, 21 Aug 2022 12:48:26 +0300
Subject: [PATCH] Sema: ignore dbg_block instructions when checking for
 comptimeness

Closes #12514
---
 src/Sema.zig           | 10 +++++-----
 test/behavior/eval.zig | 15 +++++++++++++++
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/Sema.zig b/src/Sema.zig
index 28ff4cc1c2..f3ddf21206 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -3087,7 +3087,7 @@ fn zirMakePtrConst(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileErro
 
             const candidate = block.instructions.items[search_index];
             switch (air_tags[candidate]) {
-                .dbg_stmt => continue,
+                .dbg_stmt, .dbg_block_begin, .dbg_block_end => continue,
                 .store => break candidate,
                 else => break :ct,
             }
@@ -3099,7 +3099,7 @@ fn zirMakePtrConst(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileErro
 
             const candidate = block.instructions.items[search_index];
             switch (air_tags[candidate]) {
-                .dbg_stmt => continue,
+                .dbg_stmt, .dbg_block_begin, .dbg_block_end => continue,
                 .alloc => {
                     if (Air.indexToRef(candidate) != alloc) break :ct;
                     break;
@@ -3317,7 +3317,7 @@ fn zirResolveInferredAlloc(sema: *Sema, block: *Block, inst: Zir.Inst.Index) Com
 
                     const candidate = block.instructions.items[search_index];
                     switch (air_tags[candidate]) {
-                        .dbg_stmt => continue,
+                        .dbg_stmt, .dbg_block_begin, .dbg_block_end => continue,
                         .store => break candidate,
                         else => break :ct,
                     }
@@ -3329,7 +3329,7 @@ fn zirResolveInferredAlloc(sema: *Sema, block: *Block, inst: Zir.Inst.Index) Com
 
                     const candidate = block.instructions.items[search_index];
                     switch (air_tags[candidate]) {
-                        .dbg_stmt => continue,
+                        .dbg_stmt, .dbg_block_begin, .dbg_block_end => continue,
                         .bitcast => break candidate,
                         else => break :ct,
                     }
@@ -3341,7 +3341,7 @@ fn zirResolveInferredAlloc(sema: *Sema, block: *Block, inst: Zir.Inst.Index) Com
 
                     const candidate = block.instructions.items[search_index];
                     switch (air_tags[candidate]) {
-                        .dbg_stmt => continue,
+                        .dbg_stmt, .dbg_block_begin, .dbg_block_end => continue,
                         .constant => break candidate,
                         else => break :ct,
                     }
diff --git a/test/behavior/eval.zig b/test/behavior/eval.zig
index 8a872f6378..49183227b5 100644
--- a/test/behavior/eval.zig
+++ b/test/behavior/eval.zig
@@ -1310,3 +1310,18 @@ test "repeated value is correctly expanded" {
         } }, res);
     }
 }
+
+test "value in if block is comptime known" {
+    if (builtin.zig_backend == .stage1) return error.SkipZigTest;
+
+    const first = blk: {
+        const s = if (false) "a" else "b";
+        break :blk "foo" ++ s;
+    };
+    const second = blk: {
+        const S = struct { str: []const u8 };
+        const s = if (false) S{ .str = "a" } else S{ .str = "b" };
+        break :blk "foo" ++ s.str;
+    };
+    comptime try expect(std.mem.eql(u8, first, second));
+}