fix #14850: repr now correctly renders do (#17623)

* fix #14850: `repr` now correctly renders `do`

* add tests

* fix test

compiler/renderer.nim

@@ -569,11 +569,11 @@ proc initContext(c: var TContext) =
   c.spacing = 0
   c.flags = {}
 
-proc gsub(g: var TSrcGen, n: PNode, c: TContext)
+proc gsub(g: var TSrcGen, n: PNode, c: TContext, fromStmtList = false)
-proc gsub(g: var TSrcGen, n: PNode) =
+proc gsub(g: var TSrcGen, n: PNode, fromStmtList = false) =
   var c: TContext
   initContext(c)
-  gsub(g, n, c)
+  gsub(g, n, c, fromStmtList = fromStmtList)
 
 proc hasCom(n: PNode): bool =
   result = false
@@ -681,7 +681,7 @@ proc gstmts(g: var TSrcGen, n: PNode, c: TContext, doIndent=true) =
       if n[i].kind in {nkStmtList, nkStmtListExpr, nkStmtListType}:
         gstmts(g, n[i], c, doIndent=false)
       else:
-        gsub(g, n[i])
+        gsub(g, n[i], fromStmtList = true)
       gcoms(g)
     if doIndent: dedent(g)
   else:
@@ -1003,7 +1003,7 @@ proc isCustomLit(n: PNode): bool =
     (n[1].kind == nkIdent and n[1].ident.s.startsWith('\'')) or
     (n[1].kind == nkSym and n[1].sym.name.s.startsWith('\''))
 
-proc gsub(g: var TSrcGen, n: PNode, c: TContext) =
+proc gsub(g: var TSrcGen, n: PNode, c: TContext, fromStmtList = false) =
   if isNil(n): return
   var
     a: TContext
@@ -1040,9 +1040,15 @@ proc gsub(g: var TSrcGen, n: PNode, c: TContext) =
         put(g, tkParLe, "(")
         gcomma(g, n, 1, i - 1 - n.len)
         put(g, tkParRi, ")")
-      put(g, tkColon, ":")
+      if fromStmtList:
+        put(g, tkColon, ":")
+      else:
+        put(g, tkSpaces, Space)
+        put(g, tkDo, "do")
+        put(g, tkColon, ":")
       gsub(g, n, i)
-      for j in i+1 ..< n.len:
+      i.inc
+      for j in i ..< n.len:
         optNL(g)
         put(g, tkDo, "do")
         put(g, tkColon, ":")

tests/errmsgs/twrongcolon.nim

@@ -1,7 +1,7 @@
 discard """
-errormsg: "in expression ':"
+errormsg: "in expression ' do:"
 nimout: '''
-Error: in expression ':
+Error: in expression ' do:
   890': identifier expected, but found ''
 '''
 

tests/stdlib/trepr.nim

@@ -163,5 +163,54 @@ proc `foo bar baz`(): int =
 """
     doAssert a2 == a
 
+  block: # bug #14850
+    block:
+      let a = deb:
+        template bar(): untyped =
+          foo1:
+            discard
+            4
+          foo2(1):
+            discard
+            4
+          foo3(1):
+            discard
+            4
+          do: 1
+          do: 2
+          x.add foo4
+          x.add: foo5: 3
+          x.add foo6 do: 4
+          a.add(foo7 do:
+            echo "baz"
+            4)
+
+      doAssert a == """
+
+template bar(): untyped =
+  foo1:
+    discard
+    4
+  foo2(1):
+    discard
+    4
+  foo3(1):
+    discard
+    4
+  do:
+    1
+  do:
+    2
+  x.add foo4
+  x.add:
+    foo5:
+      3
+  x.add foo6 do:
+    4
+  a.add(foo7 do:
+    echo "baz"
+    4)
+"""
+
 static: main()
 main()