add --warning:BackendWarning:off to suppress backend warnings if ev…

…er needed, as alternative to `--passc:-w` (so that it remains compiler/OS platform independent)

compiler/commands.nim

@@ -173,6 +173,15 @@ proc expectNoArg(conf: ConfigRef; switch, arg: string, pass: TCmdLinePass, info:
   if arg != "":
     localError(conf, info, "invalid argument for command line option: '$1'" % addPrefix(switch))
 
+proc handleSpecialNotes(conf: ConfigRef, pass: TCmdLinePass, note: TNoteKind) =
+  ## some notes require special handling so that cmdline flags overrides work
+  ## as expected.
+  case note
+  of warnBackendWarning:
+    if pass in {passCmd2, passPP}:
+       extccomp.addCompileOptionCmd(conf, warningsOff, isRemove = conf.hasWarn(note))
+  else: discard
+
 proc processSpecificNote*(arg: string, state: TSpecialWord, pass: TCmdLinePass,
                          info: TLineInfo; orig: string; conf: ConfigRef) =
   var id = ""  # arg = key:val or [key]:val;  with val=on|off
@@ -214,6 +223,7 @@ proc processSpecificNote*(arg: string, state: TSpecialWord, pass: TCmdLinePass,
       excl(conf.notes, n)
       excl(conf.mainPackageNotes, n)
       excl(conf.foreignPackageNotes, n)
+  handleSpecialNotes(conf, pass, n)
 
 proc processCompile(conf: ConfigRef; filename: string) =
   var found = findFile(conf, filename)

compiler/extccomp.nim

@@ -61,6 +61,7 @@ template compiler(name, settings: untyped): untyped =
 
 const
   gnuAsmListing = "-Wa,-acdl=$asmfile -g -fverbose-asm -masm=intel"
+  warningsOff* = "-w" # if needed, can be compiler specific
 
 # GNU C and C++ Compiler
 compiler gcc:
@@ -448,8 +449,12 @@ proc addCompileOption*(conf: ConfigRef; option: string) =
 proc addLinkOptionCmd*(conf: ConfigRef; option: string) =
   addOpt(conf.linkOptionsCmd, option)
 
-proc addCompileOptionCmd*(conf: ConfigRef; option: string) =
-  conf.compileOptionsCmd.add(option)
+proc addCompileOptionCmd*(conf: ConfigRef; option: string, isRemove = false) =
+  if isRemove:
+    if (var index = conf.compileOptionsCmd.find(option); index >= 0):
+      conf.compileOptionsCmd.delete(index)
+  else:
+    conf.compileOptionsCmd.add(option)
 
 proc initVars*(conf: ConfigRef) =
   # we need to define the symbol here, because ``CC`` may have never been set!

compiler/lineinfos.nim

@@ -17,6 +17,7 @@ const
 
 type
   TMsgKind* = enum
+    # errors
     errUnknown, errInternal, errIllFormedAstX, errCannotOpenFile,
     errXExpected,
     errGridTableNotImplemented,
@@ -25,6 +26,7 @@ type
     errInvalidDirectiveX,
     errGenerated,
     errUser,
+    # warnings
     warnCannotOpenFile,
     warnOctalEscape, warnXIsNeverRead, warnXmightNotBeenInit,
     warnDeprecated, warnConfigDeprecated,
@@ -37,7 +39,9 @@ type
     warnEachIdentIsTuple,
     warnProveInit, warnProveField, warnProveIndex, warnGcUnsafe, warnGcUnsafe2,
     warnUninit, warnGcMem, warnDestructor, warnLockLevel, warnResultShadowed,
-    warnInconsistentSpacing, warnCaseTransition, warnCycleCreated, warnUser,
+    warnInconsistentSpacing, warnCaseTransition, warnCycleCreated,
+    warnBackendWarning, warnUser,
+    # hints
     hintSuccess, hintSuccessX, hintCC,
     hintLineTooLong, hintXDeclaredButNotUsed,
     hintConvToBaseNotNeeded,
@@ -95,6 +99,7 @@ const
     warnInconsistentSpacing: "Number of spaces around '$#' is not consistent",
     warnCaseTransition: "Potential object case transition, instantiate new object instead",
     warnCycleCreated: "$1",
+    warnBackendWarning: "$1",
     warnUser: "$1",
     hintSuccess: "operation successful: $#",
     # keep in sync with `pegSuccess` see testament.nim
@@ -141,7 +146,7 @@ const
     "UnsafeCode", "UnusedImport", "EachIdentIsTuple",
     "ProveInit", "ProveField", "ProveIndex", "GcUnsafe", "GcUnsafe2", "Uninit",
     "GcMem", "Destructor", "LockLevel", "ResultShadowed",
-    "Spacing", "CaseTransition", "CycleCreated", "User"]
+    "Spacing", "CaseTransition", "CycleCreated", "BackendWarning", "User"]
 
   HintsToStr* = [
     "Success", "SuccessX", "CC", "LineTooLong",