revert #20719; relieve std/assertions of the sysFatal dep (#20743)

* Revert "make `system/fatal` importable (#20718)"

This reverts commit d735c447d3.

* relieve `std/assertions` of the sysFatal dep

lib/std/assertions.nim

@@ -9,8 +9,6 @@
 
 ## This module implements assertion handling.
 
-import system/fatal
-
 import std/private/miscdollars
 # ---------------------------------------------------------------------------
 # helpers
@@ -30,7 +28,7 @@ when not defined(nimHasSinkInference):
 
 proc raiseAssert*(msg: string) {.noinline, noreturn, nosinks.} =
   ## Raises an `AssertionDefect` with `msg`.
-  sysFatal(AssertionDefect, msg)
+  raise newException(AssertionDefect, msg)
 
 proc failedAssertImpl*(msg: string) {.raises: [], tags: [].} =
   ## Raises an `AssertionDefect` with `msg`, but this is hidden

lib/system.nim

@@ -1637,13 +1637,8 @@ when not defined(nimscript):
     ## for debug builds. Since it's usually used for debugging, this
     ## is proclaimed to have no IO effect!
 
-
+when not declared(sysFatal):
-when defined(nimHasExceptionsQuery):
+  include "system/fatal"
-  const gotoBasedExceptions = compileOption("exceptions", "goto")
-else:
-  const gotoBasedExceptions = false
-
-import system/fatal
 
 when not defined(nimscript):
   {.push stackTrace: off, profiler: off.}
@@ -1656,6 +1651,12 @@ when not defined(nimscript):
 when defined(nimV2):
   include system/arc
 
+template newException*(exceptn: typedesc, message: string;
+                       parentException: ref Exception = nil): untyped =
+  ## Creates an exception object of type `exceptn` and sets its `msg` field
+  ## to `message`. Returns the new exception object.
+  (ref exceptn)(msg: message, parent: parentException)
+
 when not defined(nimPreviewSlimSystem):
   {.deprecated: "assertions is about to move out of system; use `-d:nimPreviewSlimSystem` and import `std/assertions`".}
   import std/assertions
@@ -1863,12 +1864,6 @@ proc debugEcho*(x: varargs[typed, `$`]) {.magic: "Echo", noSideEffect,
   ## for debugging routines marked as `noSideEffect
   ## <manual.html#pragmas-nosideeffect-pragma>`_.
 
-template newException*(exceptn: typedesc, message: string;
-                       parentException: ref Exception = nil): untyped =
-  ## Creates an exception object of type `exceptn` and sets its `msg` field
-  ## to `message`. Returns the new exception object.
-  (ref exceptn)(msg: message, parent: parentException)
-
 when hostOS == "standalone" and defined(nogc):
   proc nimToCStringConv(s: NimString): cstring {.compilerproc, inline.} =
     if s == nil or s.len == 0: result = cstring""

lib/system/fatal.nim

@@ -9,22 +9,27 @@
 
 {.push profiler: off.}
 
+when defined(nimHasExceptionsQuery):
+  const gotoBasedExceptions = compileOption("exceptions", "goto")
+else:
+  const gotoBasedExceptions = false
+
 when hostOS == "standalone":
   include "$projectpath/panicoverride"
 
-  func sysFatal*(exceptn: typedesc, message: string) {.inline.} =
+  func sysFatal(exceptn: typedesc, message: string) {.inline.} =
     panic(message)
 
-  func sysFatal*(exceptn: typedesc, message, arg: string) {.inline.} =
+  func sysFatal(exceptn: typedesc, message, arg: string) {.inline.} =
     rawoutput(message)
     panic(arg)
 
 elif (defined(nimQuirky) or defined(nimPanics)) and not defined(nimscript):
-  import system/ansi_c
+  import ansi_c
 
   func name(t: typedesc): string {.magic: "TypeTrait".}
 
-  func sysFatal*(exceptn: typedesc, message, arg: string) {.inline, noreturn.} =
+  func sysFatal(exceptn: typedesc, message, arg: string) {.inline, noreturn.} =
     when nimvm:
       # TODO when doAssertRaises works in CT, add a test for it
       raise (ref exceptn)(msg: message & arg)
@@ -41,14 +46,14 @@ elif (defined(nimQuirky) or defined(nimPanics)) and not defined(nimscript):
         cstderr.rawWrite buf
       quit 1
 
-  func sysFatal*(exceptn: typedesc, message: string) {.inline, noreturn.} =
+  func sysFatal(exceptn: typedesc, message: string) {.inline, noreturn.} =
     sysFatal(exceptn, message, "")
 
 else:
-  func sysFatal*(exceptn: typedesc, message: string) {.inline, noreturn.} =
+  func sysFatal(exceptn: typedesc, message: string) {.inline, noreturn.} =
     raise (ref exceptn)(msg: message)
 
-  func sysFatal*(exceptn: typedesc, message, arg: string) {.inline, noreturn.} =
+  func sysFatal(exceptn: typedesc, message, arg: string) {.inline, noreturn.} =
     raise (ref exceptn)(msg: message & arg)
 
 {.pop.}

tests/assert/tassert_c.nim

@@ -8,7 +8,7 @@ tassert_c.nim(35)        tassert_c
 tassert_c.nim(34)        foo
 assertions.nim(*)       failedAssertImpl
 assertions.nim(*)       raiseAssert
-fatal.nim(*)            sysFatal"""
+"""
 
 proc tmatch(x, p: string): bool =
   var i = 0

tests/errmsgs/t9768.nim

@@ -1,10 +1,10 @@
 discard """
-  errormsg: "unhandled exception:"
+  errormsg: "unhandled exception: t9768.nim(24, 12) `a < 4`  [AssertionDefect]"
-  file: "system/fatal.nim"
+  file: "std/assertions.nim"
   nimout: '''
 stack trace: (most recent call last)
-t9768.nim(28, 33)        main
+t9768.nim(29, 33)        main
-t9768.nim(23, 11)        foo1
+t9768.nim(24, 11)        foo1
 '''
 """
 
@@ -17,6 +17,7 @@ t9768.nim(23, 11)        foo1
 
 
 
+
 ## line 20
 
 proc foo1(a: int): auto =