PointerNull is a constant.

Author: maleadt

src/core/value/constant.jl

@@ -15,14 +15,6 @@ identify(::Type{Value}, ::Val{API.LLVMUndefValueValueKind}) = UndefValue
 UndefValue(typ::LLVMType) = UndefValue(API.LLVMGetUndef(ref(typ)))
 
 
-@checked struct PointerNull <: User
-    ref::reftype(User)
-end
-identify(::Type{Value}, ::Val{API.LLVMConstantPointerNullValueKind}) = PointerNull
-
-PointerNull(typ::PointerType) = PointerNull(API.LLVMConstPointerNull(ref(typ)))
-
-
 abstract type Constant <: User end
 
 # forward declarations
@@ -32,6 +24,14 @@ end
 abstract type Instruction <: User end
 
 
+@checked struct PointerNull <: Constant
+    ref::reftype(User)
+end
+identify(::Type{Value}, ::Val{API.LLVMConstantPointerNullValueKind}) = PointerNull
+
+PointerNull(typ::PointerType) = PointerNull(API.LLVMConstPointerNull(ref(typ)))
+
+
 ## scalar
 
 export ConstantInt, ConstantFP

test/core.jl

@@ -444,6 +444,13 @@ LLVM.Module("SomeModule", ctx) do mod
         unsafe_delete!(mod, gv)
         @test isempty(gvars)
     end
+
+    # bug: PointerNull wasn't a constant, and couldn't be used as an initializer
+    let ptrtyp = LLVM.PointerType(LLVM.VoidType(ctx))
+        gv = GlobalVariable(mod, ptrtyp, "SomeOtherGlobal")
+        init = PointerNull(ptrtyp)
+        initializer!(gv, init)
+    end
 end
 end