fix #21045; getTime with vmopsDanger is broken; alternative to #21054 (#21056)

* fix #21045 getTime with vmopsDanger is broken; alternative to #21054

* typo

compiler/ccgexprs.nim

@@ -3283,6 +3283,7 @@ proc getNullValueAux(p: BProc; t: PType; obj, constOrNil: PNode,
     if constOrNil != nil:
       for i in 1..<constOrNil.len:
         if constOrNil[i].kind == nkExprColonExpr:
+          assert constOrNil[i][0].kind == nkSym, "illformed object constr; the field is not a sym"
           if constOrNil[i][0].sym.name.id == field.name.id:
             genBracedInit(p, constOrNil[i][1], isConst, field.typ, result)
             return

compiler/vmconv.nim

@@ -1,4 +1,6 @@
-import ast
+import ast, idents, lineinfos, astalgo
+import vmdef
+import std/times
 
 template elementType*(T: typedesc): typedesc =
   typeof(block:
@@ -43,3 +45,12 @@ proc toLit*[T](a: T): PNode =
   else:
     static: doAssert false, "not yet supported: " & $T # add as needed
 
+proc toTimeLit*(a: Time, c: PCtx, obj: PNode, info: TLineInfo): PNode =
+  # probably refactor it into `toLit` in the future
+  result = newTree(nkObjConstr)
+  result.add(newNode(nkEmpty)) # can be changed to a symbol according to PType
+  for k, ai in fieldPairs(a):
+    let reti = newNode(nkExprColonExpr)
+    reti.add newSymNode(lookupInRecord(obj, getIdent(c.cache, k)), info)
+    reti.add ai.toLit
+    result.add reti

compiler/vmops.nim

@@ -328,8 +328,9 @@ proc registerAdditionalOps*(c: PCtx) =
     registerCallback c, "stdlib.osproc.execCmdEx", proc (a: VmArgs) {.nimcall.} =
       let options = getNode(a, 1).fromLit(set[osproc.ProcessOption])
       a.setResult osproc.execCmdEx(getString(a, 0), options).toLit
-    registerCallback c, "stdlib.times.getTime", proc (a: VmArgs) {.nimcall.} =
-      setResult(a, times.getTime().toLit)
+    registerCallback c, "stdlib.times.getTimeImpl", proc (a: VmArgs) =
+      let obj = a.getNode(0).typ.n
+      setResult(a, times.getTime().toTimeLit(c, obj, a.currentLineInfo))
 
   proc getEffectList(c: PCtx; a: VmArgs; effectIndex: int) =
     let fn = getNode(a, 0)

lib/pure/times.nim

@@ -953,27 +953,33 @@ proc toWinTime*(t: Time): int64 =
   ## since `1601-01-01T00:00:00Z`).
   result = t.seconds * rateDiff + epochDiff + t.nanosecond div 100
 
+proc getTimeImpl(typ: typedesc[Time]): Time =
+  discard "implemented in the vm"
+
 proc getTime*(): Time {.tags: [TimeEffect], benign.} =
   ## Gets the current time as a `Time` with up to nanosecond resolution.
-  when defined(js):
-    let millis = newDate().getTime()
-    let seconds = convert(Milliseconds, Seconds, millis)
-    let nanos = convert(Milliseconds, Nanoseconds,
-      millis mod convert(Seconds, Milliseconds, 1).int)
-    result = initTime(seconds, nanos)
-  elif defined(macosx):
-    var a {.noinit.}: Timeval
-    gettimeofday(a)
-    result = initTime(a.tv_sec.int64,
-                      convert(Microseconds, Nanoseconds, a.tv_usec.int))
-  elif defined(posix):
-    var ts {.noinit.}: Timespec
-    discard clock_gettime(CLOCK_REALTIME, ts)
-    result = initTime(ts.tv_sec.int64, ts.tv_nsec.int)
-  elif defined(windows):
-    var f {.noinit.}: FILETIME
-    getSystemTimeAsFileTime(f)
-    result = fromWinTime(rdFileTime(f))
+  when nimvm:
+    result = getTimeImpl(Time)
+  else:
+    when defined(js):
+      let millis = newDate().getTime()
+      let seconds = convert(Milliseconds, Seconds, millis)
+      let nanos = convert(Milliseconds, Nanoseconds,
+        millis mod convert(Seconds, Milliseconds, 1).int)
+      result = initTime(seconds, nanos)
+    elif defined(macosx):
+      var a {.noinit.}: Timeval
+      gettimeofday(a)
+      result = initTime(a.tv_sec.int64,
+                        convert(Microseconds, Nanoseconds, a.tv_usec.int))
+    elif defined(posix):
+      var ts {.noinit.}: Timespec
+      discard clock_gettime(CLOCK_REALTIME, ts)
+      result = initTime(ts.tv_sec.int64, ts.tv_nsec.int)
+    elif defined(windows):
+      var f {.noinit.}: FILETIME
+      getSystemTimeAsFileTime(f)
+      result = fromWinTime(rdFileTime(f))
 
 proc `-`*(a, b: Time): Duration {.operator, extern: "ntDiffTime".} =
   ## Computes the duration between two points in time.

tests/vm/tvmopsDanger.nim

@@ -0,0 +1,10 @@
+discard """
+  cmd: "nim c --experimental:vmopsDanger -r $file"
+"""
+when defined(nimPreviewSlimSystem):
+  import std/assertions
+import std/times
+
+const foo = getTime()
+let bar = foo
+doAssert bar > low(Time)