delay procvar check logic to semFinishOperands

fixes nim-lang#23186

compiler/semexprs.nim

@@ -54,17 +54,6 @@ proc semOperand(c: PContext, n: PNode, flags: TExprFlags = {}): PNode =
   # same as 'semExprWithType' but doesn't check for proc vars
   result = semExpr(c, n, flags + {efOperand, efAllowSymChoice})
   if result.typ != nil:
-    # XXX tyGenericInst here?
-    if result.typ.kind == tyProc and hasUnresolvedParams(result, {efOperand}):
-      #and tfUnresolved in result.typ.flags:
-      let owner = result.typ.owner
-      let err =
-        # consistent error message with evaltempl/semMacroExpr
-        if owner != nil and owner.kind in {skTemplate, skMacro}:
-          errMissingGenericParamsForTemplate % n.renderTree
-        else:
-          errProcHasNoConcreteType % n.renderTree
-      localError(c.config, n.info, err)
     if result.typ.kind in {tyVar, tyLent}: result = newDeref(result)
   elif {efWantStmt, efAllowStmt} * flags != {}:
     result.typ = newTypeS(tyVoid, c)
@@ -1013,6 +1002,30 @@ proc bracketedMacro(n: PNode): PSym =
   else:
     result = nil
 
+proc finishOperand(c: PContext, a: PNode): PNode =
+  if a.typ.isNil:
+    result = c.semOperand(c, a, {efDetermineType})
+  else:
+    result = a
+  # XXX tyGenericInst here?
+  if result.typ.kind == tyProc and hasUnresolvedParams(result, {efOperand}):
+    #and tfUnresolved in result.typ.flags:
+    let owner = result.typ.owner
+    let err =
+      # consistent error message with evaltempl/semMacroExpr
+      if owner != nil and owner.kind in {skTemplate, skMacro}:
+        errMissingGenericParamsForTemplate % a.renderTree
+      else:
+        errProcHasNoConcreteType % a.renderTree
+    localError(c.config, a.info, err)
+  considerGenSyms(c, result)
+
+proc semFinishOperands(c: PContext; n: PNode) =
+  # this needs to be called to ensure that after overloading resolution every
+  # argument has been sem'checked:
+  for i in 1..<n.len:
+    n[i] = finishOperand(c, n[i])
+
 proc afterCallActions(c: PContext; n, orig: PNode, flags: TExprFlags; expectedType: PType = nil): PNode =
   if efNoSemCheck notin flags and n.typ != nil and n.typ.kind == tyError:
     return errorNode(c, n)

compiler/semtypinst.nim

@@ -374,6 +374,11 @@ proc handleGenericInvocation(cl: var TReplTypeVars, t: PType): PType =
         if header == t: header = instCopyType(cl, t)
         header[i] = x
         propagateToOwner(header, x)
+    elif isUnresolvedStatic(x) and not (cl.allowMetaTypes or tfRetType in x.flags):
+      # copied from error for unbound generic param in lookupTypeVar in above branch
+      localError(cl.c.config, cl.info, "cannot instantiate: '" & typeToString(x) & "'")
+      header[i] = errorType(cl.c)
+      propagateToOwner(header, x)
     else:
       propagateToOwner(header, x)
 

compiler/sigmatch.nim

@@ -2704,12 +2704,6 @@ proc matchesAux(c: PContext, n, nOrig: PNode, m: var TCandidate, marker: var Int
   m.firstMismatch.arg = a
   m.firstMismatch.formal = formal
 
-proc semFinishOperands*(c: PContext, n: PNode) =
-  # this needs to be called to ensure that after overloading resolution every
-  # argument has been sem'checked:
-  for i in 1..<n.len:
-    n[i] = prepareOperand(c, n[i])
-
 proc partialMatch*(c: PContext, n, nOrig: PNode, m: var TCandidate) =
   # for 'suggest' support:
   var marker = initIntSet()

tests/generics/t23186.nim

@@ -0,0 +1,13 @@
+# issue #23186
+
+template typedTempl(x: int, body): untyped =
+  body
+
+proc generic1[T]() =
+  discard
+
+proc generic2[T]() =
+  typedTempl(1):
+    let x = generic1[T]
+
+generic2[int]()

tests/generics/t6137.nim

@@ -1,5 +1,5 @@
 discard """
-  errormsg: "\'vectFunc\' doesn't have a concrete type, due to unspecified generic parameters."
+  errormsg: "cannot instantiate: 'T'"
   line: 28
 """