fix calls in generic bodies, delay typecheck when no overloads match (#22029)

* sacrifice "tgenericshardcases" for working statics

* legacy switch for CI, maybe experimental later

* convert to experimental

* apparently untyped needs the experimental switch

* try special case call semcheck

* try fix

* fix compilation

* final cleanup, not experimental, make `when` work

* remove last needed use of untyped

* fix unused warning in test

* remove untyped feature

Author: metagn

compiler/semcall.nim

@@ -627,7 +627,10 @@ proc semOverloadedCall(c: PContext, n, nOrig: PNode,
               candidates)
     result = semResolvedCall(c, r, n, flags)
   else:
-    if efExplain notin flags:
+    if efDetermineType in flags and c.inGenericContext > 0 and c.matchedConcept == nil:
+      result = n
+      result.typ = makeTypeFromExpr(c, result.copyTree)
+    elif efExplain notin flags:
       # repeat the overload resolution,
       # this time enabling all the diagnostic output (this should fail again)
       result = semOverloadedCall(c, n, nOrig, filter, flags + {efExplain})

compiler/semexprs.nim

@@ -971,7 +971,8 @@ proc semOverloadedCallAnalyseEffects(c: PContext, n: PNode, nOrig: PNode,
 
   if result != nil:
     if result[0].kind != nkSym:
-      internalError(c.config, "semOverloadedCallAnalyseEffects")
+      if not (efDetermineType in flags and c.inGenericContext > 0):
+        internalError(c.config, "semOverloadedCallAnalyseEffects")
       return
     let callee = result[0].sym
     case callee.kind
@@ -1007,6 +1008,8 @@ proc setGenericParams(c: PContext, n: PNode) =
 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)
+  if n.typ != nil and n.typ.kind == tyFromExpr and c.inGenericContext > 0:
+    return n
 
   result = n
 

compiler/seminst.nim

@@ -388,8 +388,7 @@ proc generateInstance(c: PContext, fn: PSym, pt: TIdTable,
       pragma(c, result, n[pragmasPos], allRoutinePragmas)
     if isNil(n[bodyPos]):
       n[bodyPos] = copyTree(getBody(c.graph, fn))
-    if c.inGenericContext == 0:
-      instantiateBody(c, n, fn.typ.n, result, fn)
+    instantiateBody(c, n, fn.typ.n, result, fn)
     sideEffectsCheck(c, result)
     if result.magic notin {mSlice, mTypeOf}:
       # 'toOpenArray' is special and it is allowed to return 'openArray':

compiler/semtypes.nim

@@ -269,6 +269,8 @@ proc semRangeAux(c: PContext, n: PNode, prev: PType): PType =
     localError(c.config, n.info, "range is empty")
 
   var range: array[2, PNode]
+  # XXX this is still a hard compilation in a generic context, this can
+  # result in unresolved generic parameters being treated like real types
   range[0] = semExprWithType(c, n[1], {efDetermineType})
   range[1] = semExprWithType(c, n[2], {efDetermineType})
 
@@ -277,7 +279,7 @@ proc semRangeAux(c: PContext, n: PNode, prev: PType): PType =
     rangeT[i] = range[i].typ.skipTypes({tyStatic}).skipIntLit(c.idgen)
 
   let hasUnknownTypes = c.inGenericContext > 0 and
-    rangeT[0].kind == tyFromExpr or rangeT[1].kind == tyFromExpr
+    (rangeT[0].kind == tyFromExpr or rangeT[1].kind == tyFromExpr)
 
   if not hasUnknownTypes:
     if not sameType(rangeT[0].skipTypes({tyRange}), rangeT[1].skipTypes({tyRange})):
@@ -337,6 +339,8 @@ proc semArrayIndex(c: PContext, n: PNode): PType =
   elif n.kind == nkInfix and n[0].kind == nkIdent and n[0].ident.s == "..<":
     result = errorType(c)
   else:
+    # XXX this is still a hard compilation in a generic context, this can
+    # result in unresolved generic parameters being treated like real types
     let e = semExprWithType(c, n, {efDetermineType})
     if e.typ.kind == tyFromExpr:
       result = makeRangeWithStaticExpr(c, e.typ.n)
@@ -357,7 +361,7 @@ proc semArrayIndex(c: PContext, n: PNode): PType =
       if not isOrdinalType(e.typ.skipTypes({tyStatic, tyAlias, tyGenericInst, tySink})):
         localError(c.config, n[1].info, errOrdinalTypeExpected % typeToString(e.typ, preferDesc))
       # This is an int returning call, depending on an
-      # yet unknown generic param (see tgenericshardcases).
+      # yet unknown generic param (see tuninstantiatedgenericcalls).
       # We are going to construct a range type that will be
       # properly filled-out in semtypinst (see how tyStaticExpr
       # is handled there).
@@ -380,7 +384,8 @@ proc semArray(c: PContext, n: PNode, prev: PType): PType =
     let indx = semArrayIndex(c, n[1])
     var indxB = indx
     if indxB.kind in {tyGenericInst, tyAlias, tySink}: indxB = lastSon(indxB)
-    if indxB.kind notin {tyGenericParam, tyStatic, tyFromExpr}:
+    if indxB.kind notin {tyGenericParam, tyStatic, tyFromExpr} and
+        tfUnresolved notin indxB.flags:
       if indxB.skipTypes({tyRange}).kind in {tyUInt, tyUInt64}:
         discard
       elif not isOrdinalType(indxB):
@@ -737,7 +742,13 @@ proc semRecordNodeAux(c: PContext, n: PNode, check: var IntSet, pos: var int,
           if e.kind != nkIntLit: discard "don't report followup error"
           elif e.intVal != 0 and branch == nil: branch = it[1]
         else:
-          it[0] = forceBool(c, semExprWithType(c, it[0]))
+          # XXX this is still a hard compilation in a generic context, this can
+          # result in unresolved generic parameters being treated like real types
+          let e = semExprWithType(c, it[0], {efDetermineType})
+          if e.typ.kind == tyFromExpr:
+            it[0] = makeStaticExpr(c, e)
+          else:
+            it[0] = forceBool(c, e)
       of nkElse:
         checkSonsLen(it, 1, c.config)
         if branch == nil: branch = it[0]

compiler/semtypinst.nim

@@ -141,27 +141,28 @@ proc isTypeParam(n: PNode): bool =
          (n.sym.kind == skGenericParam or
            (n.sym.kind == skType and sfFromGeneric in n.sym.flags))
 
-proc reResolveCallsWithTypedescParams(cl: var TReplTypeVars, n: PNode): PNode =
-  # This is needed for tgenericshardcases
-  # It's possible that a generic param will be used in a proc call to a
-  # typedesc accepting proc. After generic param substitution, such procs
-  # should be optionally instantiated with the correct type. In order to
-  # perform this instantiation, we need to re-run the generateInstance path
-  # in the compiler, but it's quite complicated to do so at the moment so we
-  # resort to a mild hack; the head symbol of the call is temporary reset and
-  # overload resolution is executed again (which may trigger generateInstance).
-  if n.kind in nkCallKinds and sfFromGeneric in n[0].sym.flags:
-    var needsFixing = false
-    for i in 1..<n.safeLen:
-      if isTypeParam(n[i]): needsFixing = true
-    if needsFixing:
-      n[0] = newSymNode(n[0].sym.owner)
-      return cl.c.semOverloadedCall(cl.c, n, n, {skProc, skFunc}, {})
-
-  for i in 0..<n.safeLen:
-    n[i] = reResolveCallsWithTypedescParams(cl, n[i])
-
-  return n
+when false: # old workaround
+  proc reResolveCallsWithTypedescParams(cl: var TReplTypeVars, n: PNode): PNode =
+    # This is needed for tuninstantiatedgenericcalls
+    # It's possible that a generic param will be used in a proc call to a
+    # typedesc accepting proc. After generic param substitution, such procs
+    # should be optionally instantiated with the correct type. In order to
+    # perform this instantiation, we need to re-run the generateInstance path
+    # in the compiler, but it's quite complicated to do so at the moment so we
+    # resort to a mild hack; the head symbol of the call is temporary reset and
+    # overload resolution is executed again (which may trigger generateInstance).
+    if n.kind in nkCallKinds and sfFromGeneric in n[0].sym.flags:
+      var needsFixing = false
+      for i in 1..<n.safeLen:
+        if isTypeParam(n[i]): needsFixing = true
+      if needsFixing:
+        n[0] = newSymNode(n[0].sym.owner)
+        return cl.c.semOverloadedCall(cl.c, n, n, {skProc, skFunc}, {})
+
+    for i in 0..<n.safeLen:
+      n[i] = reResolveCallsWithTypedescParams(cl, n[i])
+
+    return n
 
 proc replaceObjBranches(cl: TReplTypeVars, n: PNode): PNode =
   result = n
@@ -250,7 +251,8 @@ proc replaceTypeVarsN(cl: var TReplTypeVars, n: PNode; start=0): PNode =
       result = newNodeI(nkRecList, n.info)
   of nkStaticExpr:
     var n = prepareNode(cl, n)
-    n = reResolveCallsWithTypedescParams(cl, n)
+    when false:
+      n = reResolveCallsWithTypedescParams(cl, n)
     result = if cl.allowMetaTypes: n
              else: cl.c.semExpr(cl.c, n)
     if not cl.allowMetaTypes:

compiler/sigmatch.nim

@@ -1837,7 +1837,13 @@ proc typeRel(c: var TCandidate, f, aOrig: PType,
       # proc foo(T: typedesc, x: T)
       # when `f` is an unresolved typedesc, `a` could be any
       # type, so we should not perform this check earlier
-      if a.kind != tyTypeDesc:
+      if c.c.inGenericContext > 0 and
+          a.skipTypes({tyTypeDesc}).kind == tyGenericParam:
+        # generic type bodies can sometimes compile call expressions
+        # prevent unresolved generic parameters from being passed to procs as
+        # typedesc parameters
+        result = isNone
+      elif a.kind != tyTypeDesc:
         if a.kind == tyGenericParam and tfWildcard in a.flags:
           # TODO: prevent `a` from matching as a wildcard again
           result = isGeneric

compiler/types.nim

@@ -209,6 +209,8 @@ proc iterOverNode(marker: var IntSet, n: PNode, iter: TTypeIter,
       # a leaf
       result = iterOverTypeAux(marker, n.typ, iter, closure)
     else:
+      result = iterOverTypeAux(marker, n.typ, iter, closure)
+      if result: return
       for i in 0..<n.len:
         result = iterOverNode(marker, n[i], iter, closure)
         if result: return
@@ -480,6 +482,7 @@ proc valueToString(a: PNode): string =
     result = $a.intVal
   of nkFloatLit..nkFloat128Lit: result = $a.floatVal
   of nkStrLit..nkTripleStrLit: result = a.strVal
+  of nkStaticExpr: result = "static(" & a[0].renderTree & ")"
   else: result = "<invalid value>"
 
 proc rangeToStr(n: PNode): string =
@@ -1513,7 +1516,7 @@ proc compatibleEffects*(formal, actual: PType): EffectsCompat =
 
 
 proc isCompileTimeOnly*(t: PType): bool {.inline.} =
-  result = t.kind in {tyTypeDesc, tyStatic}
+  result = t.kind in {tyTypeDesc, tyStatic, tyGenericParam}
 
 proc containsCompileTimeOnly*(t: PType): bool =
   if isCompileTimeOnly(t): return true

tests/generics/tgenerics_various.nim

@@ -127,42 +127,6 @@ block trefs:
 
 
 
-block tsharedcases:
-  proc typeNameLen(x: typedesc): int {.compileTime.} =
-    result = x.name.len
-  macro selectType(a, b: typedesc): typedesc =
-    result = a
-
-  type
-    Foo[T] = object
-      data1: array[T.high, int]
-      data2: array[typeNameLen(T), float]
-      data3: array[0..T.typeNameLen, selectType(float, int)]
-    MyEnum = enum A, B, C, D
-
-  var f1: Foo[MyEnum]
-  var f2: Foo[int8]
-
-  doAssert high(f1.data1) == 2 # (D = 3) - 1 == 2
-  doAssert high(f1.data2) == 5 # (MyEnum.len = 6) - 1 == 5
-
-  doAssert high(f2.data1) == 126 # 127 - 1 == 126
-  doAssert high(f2.data2) == 3 # int8.len - 1 == 3
-
-  static:
-    doAssert high(f1.data1) == ord(C)
-    doAssert high(f1.data2) == 5 # length of MyEnum minus one, because we used T.high
-
-    doAssert high(f2.data1) == 126
-    doAssert high(f2.data2) == 3
-
-    doAssert high(f1.data3) == 6 # length of MyEnum
-    doAssert high(f2.data3) == 4 # length of int8
-
-    doAssert f2.data3[0] is float
-
-
-
 block tmap_auto:
   let x = map(@[1, 2, 3], x => x+10)
   doAssert x == @[11, 12, 13]

tests/generics/tuninstantiatedgenericcalls.nim

@@ -0,0 +1,72 @@
+# Cases that used to only work due to weird workarounds in the compiler
+# involving not instantiating calls in generic bodies which are removed
+# due to breaking statics.
+# The issue was that these calls are compiled as regular expressions at
+# the generic declaration with unresolved generic parameter types,
+# which are special cased in some places in the compiler, but sometimes
+# treated like real types.
+
+block:
+  type Base10 = object
+
+  func maxLen(T: typedesc[Base10], I: type): int8 =
+    when I is uint8:
+      3
+    elif I is uint16:
+      5
+    elif I is uint32:
+      10
+    elif I is uint64:
+      20
+    else:
+      when sizeof(uint) == 4:
+        10
+      else:
+        20
+  
+  type
+    Base10Buf[T: SomeUnsignedInt] = object
+      data: array[maxLen(Base10, T), byte]
+      len: int8
+
+  var x: Base10Buf[uint32]
+  doAssert x.data.len == 10
+  var y: Base10Buf[uint16]
+  doAssert y.data.len == 5
+
+import typetraits
+
+block thardcases:
+  proc typeNameLen(x: typedesc): int {.compileTime.} =
+    result = x.name.len
+  macro selectType(a, b: typedesc): typedesc =
+    result = a
+
+  type
+    Foo[T] = object
+      data1: array[T.high, int]
+      data2: array[typeNameLen(T), float]
+      data3: array[0..T.typeNameLen, selectType(float, int)]
+  
+  type MyEnum = enum A, B, C, D
+
+  var f1: Foo[MyEnum]
+  var f2: Foo[int8]
+
+  doAssert high(f1.data1) == 2 # (D = 3) - 1 == 2
+  doAssert high(f1.data2) == 5 # (MyEnum.len = 6) - 1 == 5
+
+  doAssert high(f2.data1) == 126 # 127 - 1 == 126
+  doAssert high(f2.data2) == 3 # int8.len - 1 == 3
+
+  static:
+    doAssert high(f1.data1) == ord(C)
+    doAssert high(f1.data2) == 5 # length of MyEnum minus one, because we used T.high
+
+    doAssert high(f2.data1) == 126
+    doAssert high(f2.data2) == 3
+
+    doAssert high(f1.data3) == 6 # length of MyEnum
+    doAssert high(f2.data3) == 4 # length of int8
+
+    doAssert f2.data3[0] is float