[bugfix] nimpretty indents multiline comments correctly (#11607)

compiler/layouter.nim

@@ -145,6 +145,10 @@ proc closeEmitter*(em: var Emitter) =
       maxLhs = 0
       lineBegin = i+1
     of ltTab:
+      if i >= 2 and em.kinds[i-2] == ltNewline and em.kinds[i-1] in {ltNewline, ltSpaces}:
+        # a previous section has ended
+        maxLhs = 0
+
       if maxLhs == 0:
         content.add em.tokens[i]
         inc lineLen, em.tokens[i].len

nimpretty/tests/exhaustive.nim

@@ -657,3 +657,22 @@ type
     key*, val*: TaintedString ## Key and value pair; the key is the option
                               ## or the argument, and the value is not "" if
                               ## the option was given a value
+
+block:
+  var t = 3
+
+## This MUST be a multiline comment,
+## single line comment would be ok.
+block:
+  var x = 7
+
+
+block:
+  var t = 3
+  ## another
+  ## multi
+
+## This MUST be a multiline comment,
+## single line comment would be ok.
+block:
+  var x = 7

nimpretty/tests/expected/exhaustive.nim

@@ -663,3 +663,22 @@ type
     key*, val*: TaintedString ## Key and value pair; the key is the option
                               ## or the argument, and the value is not "" if
                               ## the option was given a value
+
+block:
+  var t = 3
+
+## This MUST be a multiline comment,
+## single line comment would be ok.
+block:
+  var x = 7
+
+
+block:
+  var t = 3
+  ## another
+  ## multi
+
+## This MUST be a multiline comment,
+## single line comment would be ok.
+block:
+  var x = 7