stage2: better handling of file-level compile errors across updates

 * `Module.File` now retains the most recent successful ZIR in the event
   that an update causes a ZIR compile error. This way Zig does not
   throw out useful semantic analysis results when an update temporarily
   introduces a ZIR compile error.
 * Semantic analysis of a File now unconditionally creates a Decl object
   for the File. The Decl object is marked as `file_failed` in case of
   File-level compile errors. This allows detecting of the File being
   outdated, and dependency tracking just like any other Decl.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/Sema.zig b/src/Sema.zig
index 43b18d0032..50a9af4ddf 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -4387,7 +4387,7 @@ fn zirImport(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index) InnerError!
         },
     };
     try mod.semaFile(result.file);
-    return mod.constType(sema.arena, src, result.file.namespace.ty);
+    return mod.constType(sema.arena, src, result.file.namespace.?.ty);
 }
 
 fn zirShl(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index) InnerError!*Inst {
@@ -7285,7 +7285,7 @@ fn getBuiltinType(
     const opt_builtin_inst = try sema.analyzeNamespaceLookup(
         block,
         src,
-        std_file.namespace,
+        std_file.namespace.?,
         "builtin",
     );
     const builtin_inst = try sema.analyzeLoad(block, src, opt_builtin_inst.?, src);