From 27eb42c15e4e9ab547eaf02cca8810cc0e10e6bf Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Thu, 24 Feb 2022 22:27:54 -0700
Subject: Sema: implement tupleFieldVal, fix comptime elem_ptr

---
 src/Sema.zig  | 44 ++++++++++++++++++++++++++++++++++++++++++++
 src/value.zig | 40 +++++++++++++++++++++++++++++-----------
 2 files changed, 73 insertions(+), 11 deletions(-)

(limited to 'src')

diff --git a/src/Sema.zig b/src/Sema.zig
index 3ba9761cd8..ef9ba41bec 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -14360,6 +14360,10 @@ fn structFieldVal(
     assert(unresolved_struct_ty.zigTypeTag() == .Struct);
 
     const struct_ty = try sema.resolveTypeFields(block, src, unresolved_struct_ty);
+    if (struct_ty.isTuple()) {
+        return sema.tupleFieldVal(block, src, struct_byval, field_name, field_name_src, struct_ty);
+    }
+
     const struct_obj = struct_ty.castTag(.@"struct").?.data;
 
     const field_index_usize = struct_obj.fields.getIndex(field_name) orelse
@@ -14381,6 +14385,46 @@ fn structFieldVal(
     return block.addStructFieldVal(struct_byval, field_index, field.ty);
 }
 
+fn tupleFieldVal(
+    sema: *Sema,
+    block: *Block,
+    src: LazySrcLoc,
+    tuple_byval: Air.Inst.Ref,
+    field_name: []const u8,
+    field_name_src: LazySrcLoc,
+    tuple_ty: Type,
+) CompileError!Air.Inst.Ref {
+    const tuple = tuple_ty.castTag(.tuple).?.data;
+
+    if (mem.eql(u8, field_name, "len")) {
+        return sema.addIntUnsigned(Type.usize, tuple.types.len);
+    }
+
+    const field_index = std.fmt.parseUnsigned(u32, field_name, 10) catch |err| {
+        return sema.fail(block, field_name_src, "tuple {} has no such field '{s}': {s}", .{
+            tuple_ty, field_name, @errorName(err),
+        });
+    };
+
+    const field_ty = tuple.types[field_index];
+
+    if (tuple.values[field_index].tag() != .unreachable_value) {
+        return sema.addConstant(field_ty, tuple.values[field_index]);
+    }
+
+    if (try sema.resolveMaybeUndefVal(block, src, tuple_byval)) |tuple_val| {
+        if (tuple_val.isUndef()) return sema.addConstUndef(field_ty);
+        if ((try sema.typeHasOnePossibleValue(block, src, field_ty))) |opv| {
+            return sema.addConstant(field_ty, opv);
+        }
+        const field_values = tuple_val.castTag(.@"struct").?.data;
+        return sema.addConstant(field_ty, field_values[field_index]);
+    }
+
+    try sema.requireRuntimeBlock(block, src);
+    return block.addStructFieldVal(tuple_byval, field_index, field_ty);
+}
+
 fn unionFieldPtr(
     sema: *Sema,
     block: *Block,
diff --git a/src/value.zig b/src/value.zig
index 0b3ad15469..4df36f79a1 100644
--- a/src/value.zig
+++ b/src/value.zig
@@ -1851,7 +1851,13 @@ pub const Value = extern union {
 
                 return eql(a_payload.ptr, b_payload.ptr, ptr_ty);
             },
-            .elem_ptr => @panic("TODO: Implement more pointer eql cases"),
+            .elem_ptr => {
+                const a_payload = a.castTag(.elem_ptr).?.data;
+                const b_payload = b.castTag(.elem_ptr).?.data;
+                if (a_payload.index != b_payload.index) return false;
+
+                return eql(a_payload.array_ptr, b_payload.array_ptr, ty);
+            },
             .field_ptr => {
                 const a_payload = a.castTag(.field_ptr).?.data;
                 const b_payload = b.castTag(.field_ptr).?.data;
@@ -2327,21 +2333,33 @@ pub const Value = extern union {
     }
 
     /// Returns a pointer to the element value at the index.
-    pub fn elemPtr(self: Value, allocator: Allocator, index: usize) !Value {
-        switch (self.tag()) {
+    pub fn elemPtr(val: Value, arena: Allocator, index: usize) Allocator.Error!Value {
+        switch (val.tag()) {
             .elem_ptr => {
-                const elem_ptr = self.castTag(.elem_ptr).?.data;
-                return Tag.elem_ptr.create(allocator, .{
+                const elem_ptr = val.castTag(.elem_ptr).?.data;
+                return Tag.elem_ptr.create(arena, .{
                     .array_ptr = elem_ptr.array_ptr,
                     .index = elem_ptr.index + index,
                 });
             },
-            .slice => return Tag.elem_ptr.create(allocator, .{
-                .array_ptr = self.castTag(.slice).?.data.ptr,
-                .index = index,
-            }),
-            else => return Tag.elem_ptr.create(allocator, .{
-                .array_ptr = self,
+            .slice => {
+                const ptr_val = val.castTag(.slice).?.data.ptr;
+                switch (ptr_val.tag()) {
+                    .elem_ptr => {
+                        const elem_ptr = ptr_val.castTag(.elem_ptr).?.data;
+                        return Tag.elem_ptr.create(arena, .{
+                            .array_ptr = elem_ptr.array_ptr,
+                            .index = elem_ptr.index + index,
+                        });
+                    },
+                    else => return Tag.elem_ptr.create(arena, .{
+                        .array_ptr = ptr_val,
+                        .index = index,
+                    }),
+                }
+            },
+            else => return Tag.elem_ptr.create(arena, .{
+                .array_ptr = val,
                 .index = index,
             }),
         }
-- 
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