Make useVersion:1.0 disable the proc arg sym change (#15570)

* Make useVersion:1.0 disable the proc arg sym change

* Also do this for useVersion:1.2

compiler/commands.nim

@@ -883,6 +883,12 @@ proc processSwitch*(switch, arg: string, pass: TCmdLinePass, info: TLineInfo;
       undefSymbol(conf.symbols, "nimDoesntTrackDefects")
       ast.eqTypeFlags.excl {tfGcSafe, tfNoSideEffect}
       conf.globalOptions.incl optNimV1Emulation
+    of "1.2":
+      defineSymbol(conf.symbols, "NimMajor", "1")
+      defineSymbol(conf.symbols, "NimMinor", "2")
+      # always be compatible with 1.2.100:
+      defineSymbol(conf.symbols, "NimPatch", "100")
+      conf.globalOptions.incl optNimV12Emulation
     else:
       localError(conf, info, "unknown Nim version; currently supported values are: {1.0}")
   of "benchmarkvm":

compiler/options.nim

@@ -94,6 +94,7 @@ type                          # please make sure we have under 32 options
     optProduceAsm             # produce assembler code
     optPanics                 # turn panics (sysFatal) into a process termination
     optNimV1Emulation         # emulate Nim v1.0
+    optNimV12Emulation        # emulate Nim v1.2
     optSourcemap
     optProfileVM              # enable VM profiler
     optEnableDeepCopy         # ORC specific: enable 'deepcopy' for all types.

compiler/semtypes.nim

@@ -1288,7 +1288,8 @@ proc semProcTypeNode(c: PContext, n, genericParams: PNode,
       addParamOrResult(c, arg, kind)
       styleCheckDef(c.config, a[j].info, arg)
       onDef(a[j].info, arg)
-      a[j] = newSymNode(arg)
+      if {optNimV1Emulation, optNimV12Emulation} * c.config.globalOptions == {}:
+        a[j] = newSymNode(arg)
 
   var r: PType
   if n[0].kind != nkEmpty: