literal array indices (#11424)

compiler/semexprs.nim

@@ -527,16 +527,24 @@ proc semArrayConstr(c: PContext, n: PNode, flags: TExprFlags): PNode =
   result = newNodeI(nkBracket, n.info)
   result.typ = newTypeS(tyArray, c)
   rawAddSon(result.typ, nil)     # index type
+  var
+    firstIndex, lastIndex: BiggestInt = 0
+    indexType = getSysType(c.graph, n.info, tyInt)
+    lastValidIndex = lastOrd(c.config, indexType)
   if sonsLen(n) == 0:
     rawAddSon(result.typ, newTypeS(tyEmpty, c)) # needs an empty basetype!
+    lastIndex = -1
   else:
     var x = n.sons[0]
-    var lastIndex: BiggestInt = 0
-    var indexType = getSysType(c.graph, n.info, tyInt)
     if x.kind == nkExprColonExpr and sonsLen(x) == 2:
       var idx = semConstExpr(c, x.sons[0])
-      lastIndex = getOrdValue(idx)
+      if not isOrdinalType(idx.typ):
+        localError(c.config, idx.info, "expected ordinal value for array " &
+                   "index, got '$1'" % renderTree(idx))
+      firstIndex = getOrdValue(idx)
+      lastIndex = firstIndex
       indexType = idx.typ
+      lastValidIndex = lastOrd(c.config, indexType)
       x = x.sons[1]
 
     let yy = semExprWithType(c, x)
@@ -544,6 +552,12 @@ proc semArrayConstr(c: PContext, n: PNode, flags: TExprFlags): PNode =
     addSon(result, yy)
     #var typ = skipTypes(result.sons[0].typ, {tyGenericInst, tyVar, tyLent, tyOrdinal})
     for i in 1 ..< sonsLen(n):
+      if lastIndex == lastValidIndex:
+        let validIndex = makeRangeType(c, firstIndex, lastValidIndex, n.info,
+                                       indexType)
+        localError(c.config, n.info, "size of array exceeds range of index " &
+          "type '$1' by $2 elements" % [typeToString(validIndex), $(n.len-i)])
+
       x = n.sons[i]
       if x.kind == nkExprColonExpr and sonsLen(x) == 2:
         var idx = semConstExpr(c, x.sons[0])
@@ -561,7 +575,8 @@ proc semArrayConstr(c: PContext, n: PNode, flags: TExprFlags): PNode =
     addSonSkipIntLit(result.typ, typ)
     for i in 0 ..< result.len:
       result.sons[i] = fitNode(c, typ, result.sons[i], result.sons[i].info)
-  result.typ.sons[0] = makeRangeType(c, 0, sonsLen(result) - 1, n.info)
+  result.typ.sons[0] = makeRangeType(c, firstIndex, lastIndex, n.info,
+                                     indexType)
 
 proc fixAbstractType(c: PContext, n: PNode) =
   for i in 1 ..< n.len:

tests/array/tarray.nim

@@ -548,3 +548,12 @@ block t3899:
     x.a[i]
   const c = O(a: [1.0,2.0])
   echo c[2]
+
+block arrayLiterals:
+  type ABC = enum A, B, C
+  template Idx[IdxT, ElemT](arr: array[IdxT, ElemT]): untyped = IdxT
+  doAssert [A: 0, B: 1].Idx is range[A..B]
+  doAssert [A: 0, 1, 3].Idx is ABC
+  doAssert [1: 2][1] == 2
+  doAssert [-1'i8: 2][-1] == 2
+  doAssert [-1'i8: 2, 3, 4, 5].Idx is range[-1'i8..2'i8]

tests/array/tidx_lit_err1.nim

@@ -0,0 +1,6 @@
+discard """
+  errormsg: "size of array exceeds range of index type 'range 1..2(Color)' by 3 elements"
+  line: 6
+"""
+type Color = enum Red, Green, Blue
+let y = [Green: 0, 1, 2, 3, 4]

tests/array/tidx_lit_err2.nim

@@ -0,0 +1,5 @@
+discard """
+  errormsg: "expected ordinal value for array index, got '\"string\"'"
+  line: 5
+"""
+let x = ["string": 0, "index": 1]

tests/array/tidx_lit_err3.nim

@@ -0,0 +1,5 @@
+discard """
+  errormsg: "size of array exceeds range of index type 'range 2147483646..2147483647(int32)' by 1 elements"
+  line: 5
+"""
+echo [high(int32)-1: 1, 2, 3]