fixes #7827, bindSym enhancement (#8499)

* bindSym power up, working prototype

* update bindSym doc

* add bindSym test

* fix some typo

* fix bindSym doc

* get rid of specialops field from vm

* add experimental: dynamicBindSym

changelog.md

@@ -196,4 +196,9 @@
 - Nintendo Switch was added as a new platform target. See [the compiler user guide](https://nim-lang.org/docs/nimc.html)
   for more info.
 
+- macros.bindSym now capable to accepts not only literal string or string constant expression.
+  bindSym enhancement make it also can accepts computed string or ident node inside macros /
+  compile time functions / static blocks. Only in templates / regular code it retains it's old behavior.
+  This new feature can be accessed via {.experimental: "dynamicBindSym".} pragma/switch
+
 ### Bugfixes

compiler/options.nim

@@ -116,7 +116,8 @@ type
     callOperator,
     parallel,
     destructor,
-    notnil
+    notnil,
+    dynamicBindSym
 
   SymbolFilesOption* = enum
     disabledSf, writeOnlySf, readOnlySf, v2Sf

compiler/semmagic.nim

@@ -207,6 +207,67 @@ proc semBindSym(c: PContext, n: PNode): PNode =
   else:
     errorUndeclaredIdentifier(c, n.sons[1].info, sl.strVal)
 
+proc opBindSym(c: PContext, scope: PScope, n: PNode, isMixin: int, info: PNode): PNode =
+  if n.kind notin {nkStrLit, nkRStrLit, nkTripleStrLit, nkIdent}:
+    localError(c.config, info.info, errStringOrIdentNodeExpected)
+    return errorNode(c, n)
+
+  if isMixin < 0 or isMixin > high(TSymChoiceRule).int:
+    localError(c.config, info.info, errConstExprExpected)
+    return errorNode(c, n)
+
+  let id = if n.kind == nkIdent: n
+    else: newIdentNode(getIdent(c.cache, n.strVal), info.info)
+
+  let tmpScope = c.currentScope
+  c.currentScope = scope
+  let s = qualifiedLookUp(c, id, {checkUndeclared})
+  if s != nil:
+    # we need to mark all symbols:
+    result = symChoice(c, id, s, TSymChoiceRule(isMixin))
+  else:
+    errorUndeclaredIdentifier(c, info.info, if n.kind == nkIdent: n.ident.s
+      else: n.strVal)
+  c.currentScope = tmpScope
+
+proc semDynamicBindSym(c: PContext, n: PNode): PNode =
+  # inside regular code, bindSym resolves to the sym-choice
+  # nodes (see tinspectsymbol)
+  if not (c.inStaticContext > 0 or getCurrOwner(c).isCompileTimeProc):
+    return semBindSym(c, n)
+
+  if c.graph.vm.isNil:
+    setupGlobalCtx(c.module, c.graph)
+
+  let
+    vm = PCtx c.graph.vm
+    # cache the current scope to
+    # prevent it lost into oblivion
+    scope = c.currentScope
+
+  # cannot use this
+  # vm.config.features.incl dynamicBindSym
+
+  proc bindSymWrapper(a: VmArgs) =
+    # capture PContext and currentScope
+    # param description:
+    #   0. ident, a string literal / computed string / or ident node
+    #   1. bindSym rule
+    #   2. info node
+    a.setResult opBindSym(c, scope, a.getNode(0), a.getInt(1).int, a.getNode(2))
+
+  let
+    # altough we use VM callback here, it is not
+    # executed like 'normal' VM callback
+    idx = vm.registerCallback("bindSymImpl", bindSymWrapper)
+    # dummy node to carry idx information to VM
+    idxNode = newIntTypeNode(nkIntLit, idx, c.graph.getSysType(TLineInfo(), tyInt))
+
+  result = copyNode(n)
+  for x in n: result.add x
+  result.add n # info node
+  result.add idxNode
+
 proc semShallowCopy(c: PContext, n: PNode, flags: TExprFlags): PNode
 
 proc semOf(c: PContext, n: PNode): PNode =
@@ -270,7 +331,11 @@ proc magicsAfterOverloadResolution(c: PContext, n: PNode,
   of mOf: result = semOf(c, n)
   of mHigh, mLow: result = semLowHigh(c, n, n[0].sym.magic)
   of mShallowCopy: result = semShallowCopy(c, n, flags)
-  of mNBindSym: result = semBindSym(c, n)
+  of mNBindSym:
+    if dynamicBindSym notin c.features:
+      result = semBindSym(c, n)
+    else:
+      result = semDynamicBindSym(c, n)
   of mProcCall:
     result = n
     result.typ = n[1].typ

compiler/semtypes.nim

@@ -11,6 +11,7 @@
 # included from sem.nim
 
 const
+  errStringOrIdentNodeExpected = "string or ident node expected"
   errStringLiteralExpected = "string literal expected"
   errIntLiteralExpected = "integer literal expected"
   errWrongNumberOfVariables = "wrong number of variables"

compiler/vm.nim

@@ -1222,9 +1222,25 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
           node.typ.callConv == ccClosure and node.sons[0].kind == nkNilLit and
           node.sons[1].kind == nkNilLit))
     of opcNBindSym:
+      # cannot use this simple check
+      # if dynamicBindSym notin c.config.features:
+
+      # bindSym with static input
       decodeBx(rkNode)
       regs[ra].node = copyTree(c.constants.sons[rbx])
       regs[ra].node.flags.incl nfIsRef
+    of opcNDynBindSym:
+      # experimental bindSym
+      let
+        rb = instr.regB
+        rc = instr.regC
+        idx = int(regs[rb+rc-1].intVal)
+        callback = c.callbacks[idx].value
+        args = VmArgs(ra: ra, rb: rb, rc: rc, slots: cast[pointer](regs),
+                currentException: c.currentExceptionB,
+                currentLineInfo: c.debug[pc])
+      callback(args)
+      regs[ra].node.flags.incl nfIsRef
     of opcNChild:
       decodeBC(rkNode)
       let idx = regs[rc].intVal.int
@@ -1773,7 +1789,7 @@ proc getGlobalValue*(c: PCtx; s: PSym): PNode =
 
 include vmops
 
-proc setupGlobalCtx(module: PSym; graph: ModuleGraph) =
+proc setupGlobalCtx*(module: PSym; graph: ModuleGraph) =
   if graph.vm.isNil:
     graph.vm = newCtx(module, graph.cache, graph)
     registerAdditionalOps(PCtx graph.vm)

compiler/vmdef.nim

@@ -136,7 +136,7 @@ type
     opcLdGlobalAddr, # dest = addr(globals[Bx])
 
     opcLdImmInt,  # dest = immediate value
-    opcNBindSym,
+    opcNBindSym, opcNDynBindSym,
     opcSetType,   # dest.typ = types[Bx]
     opcTypeTrait,
     opcMarshalLoad, opcMarshalStore,
@@ -229,7 +229,8 @@ proc refresh*(c: PCtx, module: PSym) =
   c.prc = PProc(blocks: @[])
   c.loopIterations = MaxLoopIterations
 
-proc registerCallback*(c: PCtx; name: string; callback: VmCallback) =
+proc registerCallback*(c: PCtx; name: string; callback: VmCallback): int {.discardable.} =
+  result = c.callbacks.len
   c.callbacks.add((name, callback))
 
 const

compiler/vmgen.nim

@@ -817,6 +817,43 @@ proc genVoidABC(c: PCtx, n: PNode, dest: TDest, opcode: TOpcode) =
   c.freeTemp(tmp2)
   c.freeTemp(tmp3)
 
+proc genBindSym(c: PCtx; n: PNode; dest: var TDest) =
+  # nah, cannot use c.config.features because sempass context
+  # can have local experimental switch
+  # if dynamicBindSym notin c.config.features:
+  if n.len == 2: # hmm, reliable?
+    # bindSym with static input
+    if n[1].kind in {nkClosedSymChoice, nkOpenSymChoice, nkSym}:
+      let idx = c.genLiteral(n[1])
+      if dest < 0: dest = c.getTemp(n.typ)
+      c.gABx(n, opcNBindSym, dest, idx)
+    else:
+      localError(c.config, n.info, "invalid bindSym usage")
+  else:
+    # experimental bindSym
+    if dest < 0: dest = c.getTemp(n.typ)
+    let x = c.getTempRange(n.len, slotTempUnknown)
+
+    # callee symbol
+    var tmp0 = TDest(x)
+    c.genLit(n.sons[0], tmp0)
+
+    # original parameters
+    for i in 1..<n.len-2:
+      var r = TRegister(x+i)
+      c.gen(n.sons[i], r)
+
+    # info node
+    var tmp1 = TDest(x+n.len-2)
+    c.genLit(n.sons[^2], tmp1)
+
+    # payload idx
+    var tmp2 = TDest(x+n.len-1)
+    c.genLit(n.sons[^1], tmp2)
+
+    c.gABC(n, opcNDynBindSym, dest, x, n.len)
+    c.freeTempRange(x, n.len)
+
 proc genMagic(c: PCtx; n: PNode; dest: var TDest; m: TMagic) =
   case m
   of mAnd: c.genAndOr(n, opcFJmp, dest)
@@ -1137,13 +1174,7 @@ proc genMagic(c: PCtx; n: PNode; dest: var TDest; m: TMagic) =
   of mNNewNimNode: genBinaryABC(c, n, dest, opcNNewNimNode)
   of mNCopyNimNode: genUnaryABC(c, n, dest, opcNCopyNimNode)
   of mNCopyNimTree: genUnaryABC(c, n, dest, opcNCopyNimTree)
-  of mNBindSym:
+  of mNBindSym: genBindSym(c, n, dest)
-    if n[1].kind in {nkClosedSymChoice, nkOpenSymChoice, nkSym}:
-      let idx = c.genLiteral(n[1])
-      if dest < 0: dest = c.getTemp(n.typ)
-      c.gABx(n, opcNBindSym, dest, idx)
-    else:
-      localError(c.config, n.info, "invalid bindSym usage")
   of mStrToIdent: genUnaryABC(c, n, dest, opcStrToIdent)
   of mEqIdent: genBinaryABC(c, n, dest, opcEqIdent)
   of mEqNimrodNode: genBinaryABC(c, n, dest, opcEqNimrodNode)

lib/core/macros.nim

@@ -382,16 +382,24 @@ type
 
 {.deprecated: [TBindSymRule: BindSymRule].}
 
-proc bindSym*(ident: static[string], rule: BindSymRule = brClosed): NimNode {.
+proc bindSym*(ident: string | NimNode, rule: BindSymRule = brClosed): NimNode {.
               magic: "NBindSym", noSideEffect.}
   ## creates a node that binds `ident` to a symbol node. The bound symbol
   ## may be an overloaded symbol.
+  ## if `ident` is a NimNode, it must have nkIdent kind.
   ## If ``rule == brClosed`` either an ``nkClosedSymChoice`` tree is
   ## returned or ``nkSym`` if the symbol is not ambiguous.
   ## If ``rule == brOpen`` either an ``nkOpenSymChoice`` tree is
   ## returned or ``nkSym`` if the symbol is not ambiguous.
   ## If ``rule == brForceOpen`` always an ``nkOpenSymChoice`` tree is
   ## returned even if the symbol is not ambiguous.
+  ##
+  ## experimental feature:
+  ## use {.experimental: "dynamicBindSym".} to activate it
+  ## if called from template / regular code, `ident` and `rule` must be
+  ## constant expression / literal value.
+  ## if called from macros / compile time procs / static blocks,
+  ## `ident` and `rule` can be VM computed value.
 
 proc genSym*(kind: NimSymKind = nskLet; ident = ""): NimNode {.
   magic: "NGenSym", noSideEffect.}

tests/macros/tbindsym.nim

@@ -1,4 +1,9 @@
 discard """
+  msg: '''initApple
+deinitApple
+Coral
+enum
+  redCoral, blackCoral'''
   output: '''TFoo
 TBar'''
 """
@@ -23,3 +28,40 @@ macro test: untyped =
         bindSym("TBar"))
 
 test()
+
+# issue 7827, bindSym power up
+{.experimental: "dynamicBindSym".}
+type
+  Apple = ref object
+    name: string
+    color: int
+    weight: int
+
+proc initApple(name: string): Apple =
+  discard
+
+proc deinitApple(x: Apple) =
+  discard
+
+macro wrapObject(obj: typed, n: varargs[untyped]): untyped =
+  let m = n[0]
+  for x in m:
+    var z = bindSym x
+    echo z.repr
+
+wrapObject(Apple):
+  initApple
+  deinitApple
+
+type
+  Coral = enum
+    redCoral
+    blackCoral
+
+macro mixer(): untyped =
+  let m = "Co" & "ral"
+  let x = bindSym(m)
+  echo x.repr
+  echo getType(x).repr
+
+mixer()