nifc: fixes top level var decls with non-literals (#322)

* nifc: fixes top level var decls with non-literals

* adds AconstrC, OconstrC

* fixes

* implements `isLiteral`

src/nifc/codegen.nim

@@ -331,6 +331,25 @@ type
   VarKind = enum
     IsLocal, IsGlobal, IsThreadlocal, IsConst
 
+proc isLiteral(t: Tree; n: NodePos): bool =
+  case t[n].kind
+  of IntLit, UIntLit, FloatLit,
+      CharLit, StrLit, FalseC, TrueC, InfC, NegInfC, NanC, SufC:
+    result = true
+  of AconstrC:
+    result = true
+    for ch in sonsFromX(t, n):
+      if not isLiteral(t, ch):
+        return false
+  of OconstrC:
+    result = true
+    for ch in sonsFromX(t, n):
+      let (_, value) = sons2(t, ch)
+      if not isLiteral(t, value):
+        return false
+  else:
+    result = false
+
 proc genVarDecl(c: var GeneratedCode; t: Tree; n: NodePos; vk: VarKind; toExtern = false) =
   let d = asVarDecl(t, n)
   genCLineDir(c, t, info(t, n))
@@ -350,11 +369,23 @@ proc genVarDecl(c: var GeneratedCode; t: Tree; n: NodePos; vk: VarKind; toExtern
     if vis == StaticC:
       c.code.insert(Token(StaticKeyword), beforeDecl)
     if t[d.value].kind != Empty:
-      c.add AsgnOpr
-      if vk != IsLocal: inc c.inSimpleInit
-      genx c, t, d.value
-      if vk != IsLocal: dec c.inSimpleInit
-    c.add Semicolon
+      if vk == IsGlobal and not isLiteral(t, d.value):
+        c.add Semicolon
+        moveToInitSection:
+          c.add name
+          c.add AsgnOpr
+          inc c.inSimpleInit
+          genx c, t, d.value
+          dec c.inSimpleInit
+          c.add Semicolon
+      else:
+        c.add AsgnOpr
+        if vk != IsLocal: inc c.inSimpleInit
+        genx c, t, d.value
+        if vk != IsLocal: dec c.inSimpleInit
+        c.add Semicolon
+    else:
+      c.add Semicolon
   else:
     error c.m, "expected SymbolDef but got: ", t, n
 

tests/nimony/sysbasics/ttoplevelvars.nim

@@ -0,0 +1,17 @@
+var x = 1
+var y = 2
+x = y
+var z = x
+
+const a = 1
+var m = a
+
+let s = x
+let n = 3
+
+proc foo =
+  var m = a
+  let g = x
+  const s = a
+
+foo()