Use gProjectIsStdin instead

compiler/modules.nim

@@ -148,7 +148,7 @@ proc compileModule*(fileIdx: int32, flags: TSymFlags): PSym =
         return
     else:
       result.id = getID()
-    if sfMainModule in flags and gProjectName == "-":
+    if sfMainModule in flags and gProjectIsStdin:
       processModule(result, llStreamOpen(stdin), rd)
     else:
       processModule(result, nil, rd)

compiler/nim.nim

@@ -42,6 +42,7 @@ proc handleCmdLine() =
       gProjectName = "stdinfile"
       gProjectFull = "stdinfile"
       gProjectPath = getCurrentDir()
+      gProjectIsStdin = true
     elif gProjectName != "":
       try:
         gProjectFull = canonicalizePath(gProjectName)

compiler/options.nim

@@ -149,6 +149,7 @@ var
   gProjectName* = "" # holds a name like 'nimrod'
   gProjectPath* = "" # holds a path like /home/alice/projects/nimrod/compiler/
   gProjectFull* = "" # projectPath/projectName
+  gProjectIsStdin* = false # whether we're compiling from stdin
   gProjectMainIdx*: int32 # the canonical path id of the main module
   nimcacheDir* = ""
   command* = "" # the main command (e.g. cc, check, scan, etc)