fix scoping regression with calls in generic bodies (#22115)

refs #22029, refs https://github.com/status-im/nim-libp2p/actions/runs/5263850340/jobs/9514434659

Author: metagn

compiler/sem.nim

@@ -405,6 +405,8 @@ proc semExprFlagDispatched(c: PContext, n: PNode, flags: TExprFlags; expectedTyp
       evaluated = evalAtCompileTime(c, result)
       if evaluated != nil: return evaluated
 
+proc semGenericStmt(c: PContext, n: PNode): PNode
+
 include hlo, seminst, semcall
 
 proc resetSemFlag(n: PNode) =
@@ -513,8 +515,6 @@ proc semConstBoolExpr(c: PContext, n: PNode): PNode =
   result = forceBool(c, semConstExpr(c, n, getSysType(c.graph, n.info, tyBool)))
   if result.kind != nkIntLit:
     localError(c.config, n.info, errConstExprExpected)
-
-proc semGenericStmt(c: PContext, n: PNode): PNode
 proc semConceptBody(c: PContext, n: PNode): PNode
 
 include semtypes

compiler/semcall.nim

@@ -628,7 +628,7 @@ proc semOverloadedCall(c: PContext, n, nOrig: PNode,
     result = semResolvedCall(c, r, n, flags)
   else:
     if efDetermineType in flags and c.inGenericContext > 0 and c.matchedConcept == nil:
-      result = n
+      result = semGenericStmt(c, n)
       result.typ = makeTypeFromExpr(c, result.copyTree)
     elif efExplain notin flags:
       # repeat the overload resolution,

tests/generics/muninstantiatedgenericcalls.nim

@@ -0,0 +1,26 @@
+import std/bitops
+
+const
+  lengths = block:
+    var v: array[64, int8]
+    for i in 0..<64:
+      v[i] = int8((i + 7) div 7)
+    v
+
+type
+  Leb128* = object
+
+{.push checks: off.}
+func len(T: type Leb128, x: SomeUnsignedInt): int8 =
+  if x == 0: 1
+  else: lengths[fastLog2(x)]
+{.pop.}
+
+# note private to test scoping issue:
+func maxLen(T: type Leb128, I: type): int8 =
+  Leb128.len(I.high)
+
+type
+  Leb128Buf*[T: SomeUnsignedInt] = object
+    data*: array[maxLen(Leb128, T), byte] 
+    len*: int8

tests/generics/tuninstantiatedgenericcalls.nim

@@ -70,3 +70,11 @@ block thardcases:
     doAssert high(f2.data3) == 4 # length of int8
 
     doAssert f2.data3[0] is float
+
+import muninstantiatedgenericcalls
+
+block:
+  var x: Leb128Buf[uint32]
+  doAssert x.data.len == 5
+  var y: Leb128Buf[uint16]
+  doAssert y.data.len == 3