Upgrade to Crystal 0.29

Also updates shard.yml definition to mark that we now use LLVM 8,
and upgraded the clang and minitest dependencies.

Author: ysbaddaden

shard.lock

@@ -2,9 +2,9 @@ version: 1.0
 shards:
   clang:
     github: ysbaddaden/clang.cr
-    commit: a1a7a5612d9af79476d409994c529f076fca48ab
+    version: 0.3.0
 
   minitest:
     github: ysbaddaden/minitest.cr
-    version: 0.4.2
+    version: 0.4.3
 

shard.yml

@@ -10,15 +10,16 @@ description: |
 dependencies:
   clang:
     github: ysbaddaden/clang.cr
-    branch: master
+    version: ">= 0.3.0"
 
 development_dependencies:
   minitest:
     github: ysbaddaden/minitest.cr
+    version: ">= 0.4.3"
 
 libraries:
-  LLVM: 5.0
+  LLVM: 8
 
-crystal_version: 0.24.2
+crystal: 0.29.0
 
 license: CeCILL-C

src/ast.cr

@@ -9,11 +9,10 @@ module Runic
     end
 
     module TopLevel
-      @visited = Atomic(Int32).new(0)
+      @visited = Atomic::Flag.new
 
       def visited?
-        _, changed = @visited.compare_and_set(0, 1)
-        !changed
+        !@visited.test_and_set
       end
     end