follow up #20109; remove shallow seqs/strings for ORC (#20502)

* remove `shallow` seqs/strings for ORC

* add a changelog item

* change url of DelaunayNim

Author: ringabout

changelog.md

@@ -53,7 +53,7 @@
   or define your own `Math.trunc` polyfill using the [`emit` pragma](https://nim-lang.org/docs/manual.html#implementation-specific-pragmas-emit-pragma).
   Nim uses `Math.trunc` for the division and modulo operators for integers.
 
-- `shallowCopy` is removed for ARC/ORC. Use `move` when possible or combine assignment and
+- `shallowCopy` and `shallow` are removed for ARC/ORC. Use `move` when possible or combine assignment and
 `sink` for optimization purposes.
 
 - The `nimPreviewDotLikeOps` define is going to be removed or deprecated.

doc/nimc.md

@@ -778,20 +778,6 @@ For `let` symbols a copy is not always necessary:
   let s = varA    # may only copy a pointer if it safe to do so
   ```
 
-
-If you know what you're doing, you can also mark single-string (or sequence)
-objects as `shallow`:idx:\:
-
-  ```Nim
-  var s = "abc"
-  shallow(s) # mark 's' as a shallow string
-  var x = s  # now might not copy the string!
-  ```
-
-Usage of `shallow` is always safe once you know the string won't be modified
-anymore, similar to Ruby's `freeze`:idx:.
-
-
 The compiler optimizes string case statements: A hashing scheme is used for them
 if several different string constants are used. So code like this is reasonably
 efficient:

lib/system.nim

@@ -2313,29 +2313,30 @@ when compileOption("rangechecks"):
 else:
   template rangeCheck*(cond) = discard
 
-proc shallow*[T](s: var seq[T]) {.noSideEffect, inline.} =
-  ## Marks a sequence `s` as `shallow`:idx:. Subsequent assignments will not
-  ## perform deep copies of `s`.
-  ##
-  ## This is only useful for optimization purposes.
-  if s.len == 0: return
-  when not defined(js) and not defined(nimscript) and not defined(nimSeqsV2):
-    var s = cast[PGenericSeq](s)
-    s.reserved = s.reserved or seqShallowFlag
-
-proc shallow*(s: var string) {.noSideEffect, inline.} =
-  ## Marks a string `s` as `shallow`:idx:. Subsequent assignments will not
-  ## perform deep copies of `s`.
-  ##
-  ## This is only useful for optimization purposes.
-  when not defined(js) and not defined(nimscript) and not defined(nimSeqsV2):
-    var s = cast[PGenericSeq](s)
-    if s == nil:
-      s = cast[PGenericSeq](newString(0))
-    # string literals cannot become 'shallow':
-    if (s.reserved and strlitFlag) == 0:
+when not defined(gcArc) and not defined(gcOrc):
+  proc shallow*[T](s: var seq[T]) {.noSideEffect, inline.} =
+    ## Marks a sequence `s` as `shallow`:idx:. Subsequent assignments will not
+    ## perform deep copies of `s`.
+    ##
+    ## This is only useful for optimization purposes.
+    if s.len == 0: return
+    when not defined(js) and not defined(nimscript) and not defined(nimSeqsV2):
+      var s = cast[PGenericSeq](s)
       s.reserved = s.reserved or seqShallowFlag
 
+  proc shallow*(s: var string) {.noSideEffect, inline.} =
+    ## Marks a string `s` as `shallow`:idx:. Subsequent assignments will not
+    ## perform deep copies of `s`.
+    ##
+    ## This is only useful for optimization purposes.
+    when not defined(js) and not defined(nimscript) and not defined(nimSeqsV2):
+      var s = cast[PGenericSeq](s)
+      if s == nil:
+        s = cast[PGenericSeq](newString(0))
+      # string literals cannot become 'shallow':
+      if (s.reserved and strlitFlag) == 0:
+        s.reserved = s.reserved or seqShallowFlag
+
 type
   NimNodeObj = object
 

testament/important_packages.nim

@@ -59,7 +59,7 @@ pkg "comprehension", "nimble test", "https://github.com/alehander92/comprehensio
 pkg "criterion", allowFailure = true # pending https://github.com/disruptek/criterion/issues/3 (wrongly closed)
 pkg "datamancer"
 pkg "dashing", "nim c tests/functional.nim"
-pkg "delaunay"
+pkg "delaunay", url = "https://github.com/nim-lang/DelaunayNim", useHead = true
 pkg "docopt"
 pkg "easygl", "nim c -o:egl -r src/easygl.nim", "https://github.com/jackmott/easygl"
 pkg "elvis"

tests/collections/tseq.nim

@@ -175,12 +175,14 @@ when not defined(nimseqsv2):
       var emptySeq: seq[int] = newSeq[int]()
       block:
         var t = @[1,2,3]
-        shallow(nilSeq)
+        when defined(gcRefc):
+          shallow(nilSeq)
         t = nilSeq
         doAssert t == @[]
       block:
         var t = @[1,2,3]
-        shallow(emptySeq)
+        when defined(gcRefc):
+          shallow(emptySeq)
         t = emptySeq
         doAssert t == @[]
       block:

tests/converter/t7097.nim

@@ -10,8 +10,8 @@ proc initBytesRange*(s: var Bytes, ibegin = 0, iend = -1): BytesRange =
   let e = if iend < 0: s.len + iend + 1
           else: iend
   assert ibegin > 0 and e <= s.len
-  
-  shallow(s)
+  when defined(gcRefc):
+    shallow(s)
   result.bytes = s
   result.ibegin = ibegin
   result.iend = e

tests/converter/t7098.nim

@@ -14,8 +14,8 @@ proc initBytesRange*(s: var Bytes, ibegin = 0, iend = -1): BytesRange =
   let e = if iend < 0: s.len + iend + 1
           else: iend
   assert ibegin >= 0 and e <= s.len
-
-  shallow(s)
+  when defined(gcRefc):
+    shallow(s)
   result.bytes = s
   result.ibegin = ibegin
   result.iend = e

tests/stdlib/tstrutils2.nim

@@ -18,7 +18,8 @@ block: # setLen
 block: # forceCopy
   var a: string
   a = "foo"
-  shallow(a)
+  when defined(gcRefc):
+    shallow(a)
   var b: string
   b = a
   doAssert b[0].addr == a[0].addr

tests/system/tnilconcats.nim

@@ -26,7 +26,8 @@ when true:
 
   # casting an empty string as sequence with shallow() should not segfault
   var s2: string
-  shallow(s2)
+  when defined(gcRefc):
+    shallow(s2)
   s2 &= "foo"
   doAssert s2 == "foo"