Zir: use absolute nodes for declarations and type declarations

The justification for using relative source nodes in ZIR is that it
allows source locations -- which may be serialized across incremental
updates -- to be relative to the source location of their containing
declaration. However, having those "baseline" instructions themselves be
relative to their own parent is counterproductive, since the source
location updating problem is only being moved to `Decl`. Storing the
absolute node here instead makes more sense, since it allows for this
source location update logic to be elided entirely in the future by
storing a `TrackedInst.Index` to resolve a source location relative to
rather than a `Decl.Index`.

1 files changed, 33 insertions, 30 deletions

diff --git a/src/Sema.zig b/src/Sema.zig
index 2fcf1261a2..257f27d11a 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -2835,7 +2835,7 @@ fn zirStructDecl(
 
     const new_decl_index = try sema.createAnonymousDeclTypeNamed(
         block,
-        src,
+        extra.data.src_node,
         Value.fromInterned(wip_ty.index),
         small.name_strategy,
         "struct",
@@ -2872,7 +2872,7 @@ fn zirStructDecl(
 fn createAnonymousDeclTypeNamed(
     sema: *Sema,
     block: *Block,
-    src: LazySrcLoc,
+    src_node: std.zig.Ast.Node.Index,
     val: Value,
     name_strategy: Zir.Inst.NameStrategy,
     anon_prefix: []const u8,
@@ -2883,31 +2883,17 @@ fn createAnonymousDeclTypeNamed(
     const gpa = sema.gpa;
     const namespace = block.namespace;
     const src_decl = zcu.declPtr(block.src_decl);
-    const src_node = src_decl.relativeToNodeIndex(src.node_offset.x);
     const new_decl_index = try zcu.allocateNewDecl(namespace, src_node);
     errdefer zcu.destroyDecl(new_decl_index);
 
     switch (name_strategy) {
-        .anon => {
-            // It would be neat to have "struct:line:column" but this name has
-            // to survive incremental updates, where it may have been shifted down
-            // or up to a different line, but unchanged, and thus not unnecessarily
-            // semantically analyzed.
-            // This name is also used as the key in the parent namespace so it cannot be
-            // renamed.
-
-            const name = ip.getOrPutStringFmt(gpa, "{}__{s}_{d}", .{
-                src_decl.name.fmt(ip), anon_prefix, @intFromEnum(new_decl_index),
-            }, .no_embedded_nulls) catch unreachable;
-            try zcu.initNewAnonDecl(new_decl_index, src_decl.src_line, val, name);
-            return new_decl_index;
-        },
+        .anon => {}, // handled after switch
         .parent => {
             const name = zcu.declPtr(block.src_decl).name;
             try zcu.initNewAnonDecl(new_decl_index, src_decl.src_line, val, name);
             return new_decl_index;
         },
-        .func => {
+        .func => func_strat: {
             const fn_info = sema.code.getFnInfo(ip.funcZirBodyInst(sema.func_index).resolve(ip));
             const zir_tags = sema.code.instructions.items(.tag);
 
@@ -2927,7 +2913,7 @@ fn createAnonymousDeclTypeNamed(
                     // function and the name doesn't matter since it will later
                     // result in a compile error.
                     const arg_val = sema.resolveConstValue(block, .unneeded, arg, undefined) catch
-                        return sema.createAnonymousDeclTypeNamed(block, src, val, .anon, anon_prefix, null);
+                        break :func_strat; // fall through to anon strat
 
                     if (arg_i != 0) try writer.writeByte(',');
 
@@ -2969,9 +2955,24 @@ fn createAnonymousDeclTypeNamed(
                 },
                 else => {},
             };
-            return sema.createAnonymousDeclTypeNamed(block, src, val, .anon, anon_prefix, null);
+            // fall through to anon strat
         },
     }
+
+    // anon strat handling.
+
+    // It would be neat to have "struct:line:column" but this name has
+    // to survive incremental updates, where it may have been shifted down
+    // or up to a different line, but unchanged, and thus not unnecessarily
+    // semantically analyzed.
+    // This name is also used as the key in the parent namespace so it cannot be
+    // renamed.
+
+    const name = ip.getOrPutStringFmt(gpa, "{}__{s}_{d}", .{
+        src_decl.name.fmt(ip), anon_prefix, @intFromEnum(new_decl_index),
+    }, .no_embedded_nulls) catch unreachable;
+    try zcu.initNewAnonDecl(new_decl_index, src_decl.src_line, val, name);
+    return new_decl_index;
 }
 
 fn zirEnumDecl(
@@ -2991,7 +2992,6 @@ fn zirEnumDecl(
     var extra_index: usize = extra.end;
 
     const src = extra.data.src();
-    const tag_ty_src: LazySrcLoc = .{ .node_offset_container_tag = src.node_offset.x };
 
     const tag_type_ref = if (small.has_tag_type) blk: {
         const tag_type_ref: Zir.Inst.Ref = @enumFromInt(sema.code.extra[extra_index]);
@@ -3071,7 +3071,7 @@ fn zirEnumDecl(
 
     const new_decl_index = try sema.createAnonymousDeclTypeNamed(
         block,
-        src,
+        extra.data.src_node,
         Value.fromInterned(wip_ty.index),
         small.name_strategy,
         "enum",
@@ -3140,14 +3140,17 @@ fn zirEnumDecl(
         };
         defer enum_block.instructions.deinit(sema.gpa);
 
+        // This source location applies in the context of `enum_block`.
+        const tag_ty_src: LazySrcLoc = .{ .node_offset_container_tag = 0 };
+
         if (body.len != 0) {
             _ = try sema.analyzeInlineBody(&enum_block, body, inst);
         }
 
         if (tag_type_ref != .none) {
-            const ty = try sema.resolveType(block, tag_ty_src, tag_type_ref);
+            const ty = try sema.resolveType(&enum_block, tag_ty_src, tag_type_ref);
             if (ty.zigTypeTag(mod) != .Int and ty.zigTypeTag(mod) != .ComptimeInt) {
-                return sema.fail(block, tag_ty_src, "expected integer tag type, found '{}'", .{ty.fmt(sema.mod)});
+                return sema.fail(&enum_block, tag_ty_src, "expected integer tag type, found '{}'", .{ty.fmt(sema.mod)});
             }
             break :ty ty;
         } else if (fields_len == 0) {
@@ -3342,7 +3345,7 @@ fn zirUnionDecl(
 
     const new_decl_index = try sema.createAnonymousDeclTypeNamed(
         block,
-        src,
+        extra.data.src_node,
         Value.fromInterned(wip_ty.index),
         small.name_strategy,
         "union",
@@ -3430,7 +3433,7 @@ fn zirOpaqueDecl(
 
     const new_decl_index = try sema.createAnonymousDeclTypeNamed(
         block,
-        src,
+        extra.data.src_node,
         Value.fromInterned(wip_ty.index),
         small.name_strategy,
         "opaque",
@@ -21658,7 +21661,7 @@ fn zirReify(
 
             const new_decl_index = try sema.createAnonymousDeclTypeNamed(
                 block,
-                src,
+                mod.declPtr(block.src_decl).relativeToNodeIndex(src.node_offset.x),
                 Value.fromInterned(wip_ty.index),
                 name_strategy,
                 "opaque",
@@ -21858,7 +21861,7 @@ fn reifyEnum(
 
     const new_decl_index = try sema.createAnonymousDeclTypeNamed(
         block,
-        src,
+        mod.declPtr(block.src_decl).relativeToNodeIndex(src.node_offset.x),
         Value.fromInterned(wip_ty.index),
         name_strategy,
         "enum",
@@ -22005,7 +22008,7 @@ fn reifyUnion(
 
     const new_decl_index = try sema.createAnonymousDeclTypeNamed(
         block,
-        src,
+        mod.declPtr(block.src_decl).relativeToNodeIndex(src.node_offset.x),
         Value.fromInterned(wip_ty.index),
         name_strategy,
         "union",
@@ -22264,7 +22267,7 @@ fn reifyStruct(
 
     const new_decl_index = try sema.createAnonymousDeclTypeNamed(
         block,
-        src,
+        mod.declPtr(block.src_decl).relativeToNodeIndex(src.node_offset.x),
         Value.fromInterned(wip_ty.index),
         name_strategy,
         "struct",