nimfix can fix obsolete statement comments

compiler/prettybase.nim

@@ -54,9 +54,20 @@ proc replaceDeprecated*(info: TLineInfo; oldSym, newSym: PIdent) =
   
   let last = first+identLen(line, first)-1
   if cmpIgnoreStyle(line[first..last], oldSym.s) == 0:
-    var x = line.substr(0, first-1) & newSym.s & line.substr(last+1)    
+    var x = line.substr(0, first-1) & newSym.s & line.substr(last+1)
     system.shallowCopy(gSourceFiles[info.fileIndex].lines[info.line-1], x)
     gSourceFiles[info.fileIndex].dirty = true
 
 proc replaceDeprecated*(info: TLineInfo; oldSym, newSym: PSym) =
   replaceDeprecated(info, oldSym.name, newSym.name)
+
+proc replaceComment*(info: TLineInfo) =
+  loadFile(info)
+
+  let line = gSourceFiles[info.fileIndex].lines[info.line-1]
+  var first = info.col.int
+  if line[first] != '#': inc first
+
+  var x = line.substr(0, first-1) & "discard " & line.substr(first+1).escape
+  system.shallowCopy(gSourceFiles[info.fileIndex].lines[info.line-1], x)
+  gSourceFiles[info.fileIndex].dirty = true

compiler/sem.nim

@@ -18,6 +18,9 @@ import
   evaltempl, patterns, parampatterns, sempass2, pretty, semmacrosanity,
   semparallel, lowerings
 
+when defined(nimfix):
+  import prettybase
+
 # implementation
 
 proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}): PNode {.procvar.}

compiler/semstmts.nim

@@ -1398,6 +1398,11 @@ proc semStmtList(c: PContext, n: PNode, flags: TExprFlags): PNode =
       else: discard
   if result.len == 1:
     result = result.sons[0]
+  when defined(nimfix):
+    if result.kind == nkCommentStmt and not result.comment.isNil and
+        not (result.comment[0] == '#' and result.comment[1] == '#'):
+      # it is an old-style comment statement: we replace it with 'discard ""':
+      prettybase.replaceComment(result.info)
   when false:
     # a statement list (s; e) has the type 'e':
     if result.kind == nkStmtList and result.len > 0: