fixes #24941; missing < (less than), cmp for cstring (#24942)

fixes #24941

now `cmp` can select the correct version of cstring comparsions

(cherry picked from commit 42a4adb4a5)

compiler/vmops.nim

@@ -335,6 +335,12 @@ proc registerAdditionalOps*(c: PCtx) =
   registerCallback c, "stdlib.hashes.hashVmImplByte", hashVmImplByte
   registerCallback c, "stdlib.hashes.hashVmImplChar", hashVmImplByte
 
+  registerCallback c, "stdlib.system.ltCStringVm", proc (a: VmArgs) =
+    setResult(a, getString(a, 0) < getString(a, 1))
+
+  registerCallback c, "stdlib.system.leCStringVm", proc (a: VmArgs) =
+    setResult(a, getString(a, 0) <= getString(a, 1))
+
   if optBenchmarkVM in c.config.globalOptions or vmopsDanger in c.config.features:
     wrap0(cpuTime, timesop)
   else:

lib/system.nim

@@ -2720,16 +2720,53 @@ proc procCall*(x: untyped) {.magic: "ProcCall", compileTime.} =
   ##   ```
   discard
 
+proc strcmp(a, b: cstring): cint {.noSideEffect,
+  importc, header: "<string.h>".}
 
 proc `==`*(x, y: cstring): bool {.magic: "EqCString", noSideEffect,
                                    inline.} =
   ## Checks for equality between two `cstring` variables.
-  proc strcmp(a, b: cstring): cint {.noSideEffect,
-    importc, header: "<string.h>".}
   if pointer(x) == pointer(y): result = true
   elif pointer(x) == nil or pointer(y) == nil: result = false
   else: result = strcmp(x, y) == 0
 
+func ltCStringVm(x, y: cstring): bool {.inline.} =
+  discard "implemented in the vm ops"
+
+func leCStringVm(x, y: cstring): bool {.inline.} =
+  discard "implemented in the vm ops"
+
+func `<`*(x, y: cstring): bool {.inline.} =
+  if x == y:
+    result = false
+  elif x == nil:
+    result = true
+  elif y == nil:
+    result = false
+  else:
+    when nimvm:
+      result = ltCStringVm(x, y)
+    else:
+      when defined(js):
+        result = pointer(x) < pointer(y)
+      else:
+        result = strcmp(x, y) < 0
+
+func `<=`*(x, y: cstring): bool {.inline.} =
+  if x == y: result = true
+  elif x == nil:
+    result = true
+  elif y == nil:
+    result = false
+  else:
+    when nimvm:
+      result = leCStringVm(x, y)
+    else:
+      when defined(js):
+        result = pointer(x) <= pointer(y)
+      else:
+        result = strcmp(x, y) <= 0
+
 template closureScope*(body: untyped): untyped =
   ## Useful when creating a closure in a loop to capture local loop variables by
   ## their current iteration values.

tests/sets/t15435.nim

@@ -7,7 +7,7 @@ proc `<`[T](x, y: set[T]): bool
   first type mismatch at position: 2
   required type for y: set[T]
   but expression 'x' is of type: set[range 1..5(uint8)]
-20 other mismatching symbols have been suppressed; compile with --showAllMismatches:on to see them
+21 other mismatching symbols have been suppressed; compile with --showAllMismatches:on to see them
 
 expression: {1'u8, 5} < x'''
 """

tests/stdlib/tsystem.nim

@@ -198,3 +198,43 @@ block: # bug #6549
       doAssert $v == "18446744073709551615"
       doAssert $float32(v) == "1.8446744e+19"
       doAssert $float64(v) == "1.8446744073709552e+19"
+
+proc bar2() =
+  var a = cstring"1233"
+  var b = cstring"1233"
+
+  if a == b: doAssert not(a<b)
+  doAssert not (a != b)
+  doAssert a <= b
+  doAssert not (a > b)
+  doAssert a >= b
+  doAssert not (a < b)
+
+  var c = cstring"a1345"
+  var d = cstring"hwr"
+  doAssert c < d
+  doAssert c <= d
+  doAssert not (c > d)
+  doAssert not (c > d)
+  doAssert c != d
+  doAssert not (c == d)
+
+  when not defined(js):
+    doAssert cstring(nil) < cstring""
+    doAssert cstring(nil) <= cstring""
+    doAssert not (cstring"" < cstring(nil))
+    doAssert not (cstring"" <= cstring(nil))
+    doAssert not (cstring(nil) > cstring"")
+    doAssert not (cstring(nil) >= cstring"")
+    doAssert cstring"" > cstring(nil)
+    doAssert cstring"" >= cstring(nil)
+    doAssert not (cstring"" == cstring(nil))
+    doAssert cstring(nil) != cstring""
+    doAssert cstring(nil) == cstring(nil)
+    doAssert cstring(nil) >= cstring(nil)
+    doAssert cstring("") >= cstring("")
+    doAssert cstring(nil) <= cstring(nil)
+    doAssert cstring("") <= cstring("")
+
+static: bar2()
+bar2()