From 3464351d1e0a1e840d0b1a6267d0a5bf4113cfcc Mon Sep 17 00:00:00 2001
From: Michael Dusan <michael.dusan@gmail.com>
Date: Thu, 10 Oct 2019 04:55:09 -0400
Subject: [PATCH] stage1: fix ir_resolve_str() to return slice

`ir_resolve_str()` bug returns array expression even when when sliced
to a lesser length. Fix is to return array if slice.len == array.len,
otherwise return slice.

Bug report use-case is based on one builtin function. However, at least
the following builtins were exposed to the bug:

    `@byteOffsetOf`
    `@cDefine`
    `@cImport`
    `@cInclude`
    `@cUndef`
    `@compileError`
    `@embedFile`
    `@export`
    `@fieldParentPtr`
    `@hasDecl`
    `@hasField`
    `@import`
    `@unionInit`

closes #3384
---
 src/ir.cpp                         |  7 +++----
 test/stage1/behavior.zig           |  1 +
 test/stage1/behavior/bugs/3384.zig | 11 +++++++++++
 3 files changed, 15 insertions(+), 4 deletions(-)
 create mode 100644 test/stage1/behavior/bugs/3384.zig

diff --git a/src/ir.cpp b/src/ir.cpp
index 0e6153ebcd66d6a51d4ffb0b7db5caa42e55790a..8fecbf7a187f046db46fa5cc120f87ded5d7bdb5 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -13122,7 +13122,6 @@ static bool ir_resolve_float_mode(IrAnalyze *ira, IrInstruction *value, FloatMod
     return true;
 }
 
-
 static Buf *ir_resolve_str(IrAnalyze *ira, IrInstruction *value) {
     if (type_is_invalid(value->value.type))
         return nullptr;
@@ -13143,11 +13142,11 @@ static Buf *ir_resolve_str(IrAnalyze *ira, IrInstruction *value) {
 
     assert(ptr_field->data.x_ptr.special == ConstPtrSpecialBaseArray);
     ConstExprValue *array_val = ptr_field->data.x_ptr.data.base_array.array_val;
-    if (array_val->data.x_array.special == ConstArraySpecialBuf) {
-        return array_val->data.x_array.data.s_buf;
-    }
     expand_undef_array(ira->codegen, array_val);
     size_t len = bigint_as_usize(&len_field->data.x_bigint);
+    if (array_val->data.x_array.special == ConstArraySpecialBuf && len == buf_len(array_val->data.x_array.data.s_buf)) {
+        return array_val->data.x_array.data.s_buf;
+    }
     Buf *result = buf_alloc();
     buf_resize(result, len);
     for (size_t i = 0; i < len; i += 1) {
diff --git a/test/stage1/behavior.zig b/test/stage1/behavior.zig
index 95cb98f8eb4d65ef198665ddc179bf7aa6ea2527..95d2dbac93beaac5c741e429fd6481934fddd340 100644
--- a/test/stage1/behavior.zig
+++ b/test/stage1/behavior.zig
@@ -35,6 +35,7 @@ comptime {
     _ = @import("behavior/bugs/3046.zig");
     _ = @import("behavior/bugs/3112.zig");
     _ = @import("behavior/bugs/3367.zig");
+    _ = @import("behavior/bugs/3384.zig");
     _ = @import("behavior/bugs/394.zig");
     _ = @import("behavior/bugs/421.zig");
     _ = @import("behavior/bugs/529.zig");
diff --git a/test/stage1/behavior/bugs/3384.zig b/test/stage1/behavior/bugs/3384.zig
new file mode 100644
index 0000000000000000000000000000000000000000..789b0be51648992870483caf148e141d2e3d9018
--- /dev/null
+++ b/test/stage1/behavior/bugs/3384.zig
@@ -0,0 +1,11 @@
+const std = @import("std");
+const expect = std.testing.expect;
+
+test "resolve array slice using builtin" {
+    expect(@hasDecl(@This(), "std") == true);
+    expect(@hasDecl(@This(), "std"[0..0]) == false);
+    expect(@hasDecl(@This(), "std"[0..1]) == false);
+    expect(@hasDecl(@This(), "std"[0..2]) == false);
+    expect(@hasDecl(@This(), "std"[0..3]) == true);
+    expect(@hasDecl(@This(), "std"[0..]) == true);
+}
-- 
2.54.0