fixes #5131

compiler/vmdeps.nim

@@ -174,7 +174,7 @@ proc mapTypeToAstX(t: PType; info: TLineInfo;
         for i in 1 .. < t.len-1:
           result.add mapTypeToAst(t.sons[i], info)
     else:
-      result = mapTypeToAst(t.lastSon, info)
+      result = mapTypeToAstX(t.lastSon, info, inst, allowRecursion)
   of tyGenericBody, tyOrdinal, tyUserTypeClassInst:
     result = mapTypeToAst(t.lastSon, info)
   of tyDistinct:

tests/macros/tgettype3.nim

@@ -0,0 +1,48 @@
+discard """
+  output: "vec2"
+"""
+# bug #5131
+
+import macros
+
+type
+    vecBase[I: static[int], T] = distinct array[I, T]
+    vec2* = vecBase[2, float32]
+
+proc isRange(n: NimNode, rangeLen: int = -1): bool =
+    if n.kind == nnkBracketExpr and $(n[0]) == "range":
+        if rangeLen == -1:
+            result = true
+        elif n[2].intVal - n[1].intVal + 1 == rangeLen:
+            result = true
+
+proc getTypeName(t: NimNode, skipVar = false): string =
+    case t.kind
+    of nnkBracketExpr:
+        if $(t[0]) == "array" and t[1].isRange(2) and $(t[2]) == "float32":
+            result = "vec2"
+        elif $(t[0]) == "array" and t[1].isRange(3) and $(t[2]) == "float32":
+            result = "vec3"
+        elif $(t[0]) == "array" and t[1].isRange(4) and $(t[2]) == "float32":
+            result = "vec4"
+        elif $(t[0]) == "distinct":
+            result = getTypeName(t[1], skipVar)
+    of nnkSym:
+        case $t
+        of "vecBase": result = getTypeName(getType(t), skipVar)
+        of "float32": result = "float"
+        else:
+            result = $t
+    of nnkVarTy:
+        result = getTypeName(t[0])
+        if not skipVar:
+            result = "inout " & result
+    else:
+        echo "UNKNOWN TYPE: ", treeRepr(t)
+        assert(false, "Unknown type")
+
+macro typeName(t: typed): string =
+    result = newLit(getTypeName(getType(t)))
+
+var tt : vec2
+echo typeName(tt)