fixes ptr to cstring warnings[backport] (#20848)

* fix =#13790 ptr char (+friends) should not implicitly convert to cstring

* Apply suggestions from code review

* first round; compiles on windows

* nimPreviewSlimSystem

* conversion is unsafe, cast needed

* fixes more tests

* fixes asyncnet

* another try another error

* last one

* true

* one more

* why bugs didn't show at once

* add `nimPreviewCstringConversion` switch

* typo

* fixes ptr to cstring warnings[backport]

* add fixes

Co-authored-by: xflywind <43030857+xflywind@users.noreply.github.com>

19 files changed, 41 insertions, 41 deletions

diff --git a/lib/impure/db_odbc.nim b/lib/impure/db_odbc.nim
index 2427f64fa..62f047b49 100644
--- a/lib/impure/db_odbc.nim
+++ b/lib/impure/db_odbc.nim
@@ -137,7 +137,7 @@ proc getErrInfo(db: var DbConn): tuple[res: int, ss, ne, msg: string] {.
               511.TSqlSmallInt, retSz.addr)
   except:
     discard
-  return (res.int, $(addr sqlState), $(addr nativeErr), $(addr errMsg))
+  return (res.int, $(cast[cstring](addr sqlState)), $cast[cstring](addr nativeErr), $cast[cstring](addr errMsg))
 
 proc dbError*(db: var DbConn) {.
           tags: [ReadDbEffect, WriteDbEffect], raises: [DbError] .} =
@@ -187,7 +187,7 @@ proc sqlGetDBMS(db: var DbConn): string {.
     db.sqlCheck(SQLGetInfo(db.hDb, SQL_DBMS_NAME, cast[SqlPointer](buf.addr),
                         4095.TSqlSmallInt, sz.addr))
   except: discard
-  return $(addr buf)
+  return $(cast[cstring](addr buf))
 
 proc dbQuote*(s: string): string {.noSideEffect.} =
   ## DB quotes the string.
@@ -291,7 +291,7 @@ iterator fastRows*(db: var DbConn, query: SqlQuery,
         buf[0] = '\0'
         db.sqlCheck(SQLGetData(db.stmt, colId.SqlUSmallInt, SQL_C_CHAR,
                                  cast[cstring](buf.addr), 4095, sz.addr))
-        rowRes[colId-1] = $(addr buf)
+        rowRes[colId-1] = $cast[cstring]((addr buf))
       yield rowRes
       res = SQLFetch(db.stmt)
   properFreeResult(SQL_HANDLE_STMT, db.stmt)
@@ -319,7 +319,7 @@ iterator instantRows*(db: var DbConn, query: SqlQuery,
         buf[0] = '\0'
         db.sqlCheck(SQLGetData(db.stmt, colId.SqlUSmallInt, SQL_C_CHAR,
                                  cast[cstring](buf.addr), 4095, sz.addr))
-        rowRes[colId-1] = $(addr buf)
+        rowRes[colId-1] = $cast[cstring](addr buf)
       yield (row: rowRes, len: cCnt.int)
       res = SQLFetch(db.stmt)
   properFreeResult(SQL_HANDLE_STMT, db.stmt)
@@ -358,7 +358,7 @@ proc getRow*(db: var DbConn, query: SqlQuery,
       buf[0] = '\0'
       db.sqlCheck(SQLGetData(db.stmt, colId.SqlUSmallInt, SQL_C_CHAR,
                                cast[cstring](buf.addr), 4095, sz.addr))
-      rowRes[colId-1] = $(addr buf)
+      rowRes[colId-1] = $cast[cstring](addr buf)
     res = SQLFetch(db.stmt)
     result = rowRes
   properFreeResult(SQL_HANDLE_STMT, db.stmt)
@@ -386,7 +386,7 @@ proc getAllRows*(db: var DbConn, query: SqlQuery,
         buf[0] = '\0'
         db.sqlCheck(SQLGetData(db.stmt, colId.SqlUSmallInt, SQL_C_CHAR,
                                  cast[cstring](buf.addr), 4095, sz.addr))
-        rowRes[colId-1] = $(addr buf)
+        rowRes[colId-1] = $cast[cstring](addr buf)
       rows.add(rowRes)
       res = SQLFetch(db.stmt)
     result = rows
diff --git a/lib/posix/posix_utils.nim b/lib/posix/posix_utils.nim
index 0bd83b27b..92fe0940d 100644
--- a/lib/posix/posix_utils.nim
+++ b/lib/posix/posix_utils.nim
@@ -21,7 +21,7 @@ type Uname* = object
   sysname*, nodename*, release*, version*, machine*: string
 
 template charArrayToString(input: typed): string =
-  $cstring(addr input)
+  $cast[cstring](addr input)
 
 proc uname*(): Uname =
   ## Provides system information in a `Uname` struct with sysname, nodename,
diff --git a/lib/pure/asyncnet.nim b/lib/pure/asyncnet.nim
index ea0ae1f69..982459af7 100644
--- a/lib/pure/asyncnet.nim
+++ b/lib/pure/asyncnet.nim
@@ -229,7 +229,7 @@ when defineSsl:
     let len = bioCtrlPending(socket.bioOut)
     if len > 0:
       var data = newString(len)
-      let read = bioRead(socket.bioOut, addr data[0], len)
+      let read = bioRead(socket.bioOut, cast[cstring](addr data[0]), len)
       assert read != 0
       if read < 0:
         raiseSSLError()
@@ -247,7 +247,7 @@ when defineSsl:
       var data = await recv(socket.fd.AsyncFD, BufferSize, flags)
       let length = len(data)
       if length > 0:
-        let ret = bioWrite(socket.bioIn, addr data[0], length.cint)
+        let ret = bioWrite(socket.bioIn, cast[cstring](addr data[0]), length.cint)
         if ret < 0:
           raiseSSLError()
       elif length == 0:
@@ -459,7 +459,7 @@ proc send*(socket: AsyncSocket, data: string,
     when defineSsl:
       var copy = data
       sslLoop(socket, flags,
-        sslWrite(socket.sslHandle, addr copy[0], copy.len.cint))
+        sslWrite(socket.sslHandle, cast[cstring](addr copy[0]), copy.len.cint))
       await sendPendingSslData(socket, flags)
   else:
     await send(socket.fd.AsyncFD, data, flags)
diff --git a/lib/pure/nativesockets.nim b/lib/pure/nativesockets.nim
index 2599a8acc..14a318412 100644
--- a/lib/pure/nativesockets.nim
+++ b/lib/pure/nativesockets.nim
@@ -481,13 +481,13 @@ when not useNimNetLite:
       result = newString(addrLen)
       let addr6 = addr cast[ptr Sockaddr_in6](sockAddr).sin6_addr
       when not useWinVersion:
-        if posix.inet_ntop(posix.AF_INET6, addr6, addr result[0],
+        if posix.inet_ntop(posix.AF_INET6, addr6, cast[cstring](addr result[0]),
                           result.len.int32) == nil:
           raiseOSError(osLastError())
         if posix.IN6_IS_ADDR_V4MAPPED(addr6) != 0:
           result.setSlice("::ffff:".len..<addrLen)
       else:
-        if winlean.inet_ntop(winlean.AF_INET6, addr6, addr result[0],
+        if winlean.inet_ntop(winlean.AF_INET6, addr6, cast[cstring](addr result[0]),
                             result.len.int32) == nil:
           raiseOSError(osLastError())
       setLen(result, len(cstring(result)))
@@ -509,23 +509,23 @@ when not useNimNetLite:
     if sockAddr.sa_family.cint == nativeAfInet:
       let addr4 = addr cast[ptr Sockaddr_in](sockAddr).sin_addr
       when not useWinVersion:
-        if posix.inet_ntop(posix.AF_INET, addr4, addr strAddress[0],
+        if posix.inet_ntop(posix.AF_INET, addr4, cast[cstring](addr strAddress[0]),
                           strAddress.len.int32) == nil:
           raiseOSError(osLastError())
       else:
-        if winlean.inet_ntop(winlean.AF_INET, addr4, addr strAddress[0],
+        if winlean.inet_ntop(winlean.AF_INET, addr4, cast[cstring](addr strAddress[0]),
                             strAddress.len.int32) == nil:
           raiseOSError(osLastError())
     elif sockAddr.sa_family.cint == nativeAfInet6:
       let addr6 = addr cast[ptr Sockaddr_in6](sockAddr).sin6_addr
       when not useWinVersion:
-        if posix.inet_ntop(posix.AF_INET6, addr6, addr strAddress[0],
+        if posix.inet_ntop(posix.AF_INET6, addr6, cast[cstring](addr strAddress[0]),
                           strAddress.len.int32) == nil:
           raiseOSError(osLastError())
         if posix.IN6_IS_ADDR_V4MAPPED(addr6) != 0:
           strAddress.setSlice("::ffff:".len..<length)
       else:
-        if winlean.inet_ntop(winlean.AF_INET6, addr6, addr strAddress[0],
+        if winlean.inet_ntop(winlean.AF_INET6, addr6, cast[cstring](addr strAddress[0]),
                             strAddress.len.int32) == nil:
           raiseOSError(osLastError())
     else:
@@ -584,7 +584,7 @@ when not useNimNetLite:
       # Cannot use INET6_ADDRSTRLEN here, because it's a C define.
       result[0] = newString(64)
       if inet_ntop(name.sin6_family.cint,
-          addr name.sin6_addr, addr result[0][0], (result[0].len+1).int32).isNil:
+          addr name.sin6_addr, cast[cstring](addr result[0][0]), (result[0].len+1).int32).isNil:
         raiseOSError(osLastError())
       setLen(result[0], result[0].cstring.len)
       result[1] = Port(nativesockets.ntohs(name.sin6_port))
@@ -621,7 +621,7 @@ when not useNimNetLite:
       # Cannot use INET6_ADDRSTRLEN here, because it's a C define.
       result[0] = newString(64)
       if inet_ntop(name.sin6_family.cint,
-          addr name.sin6_addr, addr result[0][0], (result[0].len+1).int32).isNil:
+          addr name.sin6_addr, cast[cstring](addr result[0][0]), (result[0].len+1).int32).isNil:
         raiseOSError(osLastError())
       setLen(result[0], result[0].cstring.len)
       result[1] = Port(nativesockets.ntohs(name.sin6_port))
diff --git a/lib/pure/strutils.nim b/lib/pure/strutils.nim
index 2e408f438..8b3d36f66 100644
--- a/lib/pure/strutils.nim
+++ b/lib/pure/strutils.nim
@@ -2435,11 +2435,11 @@ func formatBiggestFloat*(f: BiggestFloat, format: FloatFormatMode = ffDefault,
       frmtstr[3] = '*'
       frmtstr[4] = floatFormatToChar[format]
       frmtstr[5] = '\0'
-      L = c_sprintf(addr buf, addr frmtstr, precision, f)
+      L = c_sprintf(cast[cstring](addr buf), cast[cstring](addr frmtstr), precision, f)
     else:
       frmtstr[1] = floatFormatToChar[format]
       frmtstr[2] = '\0'
-      L = c_sprintf(addr buf, addr frmtstr, f)
+      L = c_sprintf(cast[cstring](addr buf), cast[cstring](addr frmtstr), f)
     result = newString(L)
     for i in 0 ..< L:
       # Depending on the locale either dot or comma is produced,
diff --git a/lib/std/formatfloat.nim b/lib/std/formatfloat.nim
index 6f2383760..2850f7021 100644
--- a/lib/std/formatfloat.nim
+++ b/lib/std/formatfloat.nim
@@ -49,7 +49,7 @@ proc writeFloatToBufferSprintf*(buf: var array[65, char]; value: BiggestFloat):
   ##
   ## returns the amount of bytes written to `buf` not counting the
   ## terminating '\0' character.
-  var n: int = c_sprintf(addr buf, "%.16g", value)
+  var n: int = c_sprintf(cast[cstring](addr buf), "%.16g", value)
   var hasDot = false
   for i in 0..n-1:
     if buf[i] == ',':
@@ -90,7 +90,7 @@ proc addFloatRoundtrip*(result: var string; x: float | float32) =
   else:
     var buffer {.noinit.}: array[65, char]
     let n = writeFloatToBufferRoundtrip(buffer, x)
-    result.addCstringN(cstring(buffer[0].addr), n)
+    result.addCstringN(cast[cstring](buffer[0].addr), n)
 
 proc addFloatSprintf*(result: var string; x: float) =
   when nimvm:
@@ -98,7 +98,7 @@ proc addFloatSprintf*(result: var string; x: float) =
   else:
     var buffer {.noinit.}: array[65, char]
     let n = writeFloatToBufferSprintf(buffer, x)
-    result.addCstringN(cstring(buffer[0].addr), n)
+    result.addCstringN(cast[cstring](buffer[0].addr), n)
 
 proc nimFloatToString(a: float): cstring =
   ## ensures the result doesn't print like an integer, i.e. return 2.0, not 2
diff --git a/lib/std/private/oscommon.nim b/lib/std/private/oscommon.nim
index 66725395f..bab4856ca 100644
--- a/lib/std/private/oscommon.nim
+++ b/lib/std/private/oscommon.nim
@@ -63,7 +63,7 @@ when defined(windows) and not weirdTarget:
     template findNextFile*(a, b: untyped): untyped = findNextFileA(a, b)
     template getCommandLine*(): untyped = getCommandLineA()
 
-    template getFilename*(f: untyped): untyped = $cstring(addr f.cFileName)
+    template getFilename*(f: untyped): untyped = $cast[cstring](addr f.cFileName)
 
   proc skipFindData*(f: WIN32_FIND_DATA): bool {.inline.} =
     # Note - takes advantage of null delimiter in the cstring
diff --git a/lib/std/private/osdirs.nim b/lib/std/private/osdirs.nim
index 4b349817c..add9ed424 100644
--- a/lib/std/private/osdirs.nim
+++ b/lib/std/private/osdirs.nim
@@ -231,7 +231,7 @@ iterator walkDir*(dir: string; relative = false, checkDir = false,
         while true:
           var x = readdir(d)
           if x == nil: break
-          var y = $cstring(addr x.d_name)
+          var y = $cast[cstring](addr x.d_name)
           if y != "." and y != "..":
             var s: Stat
             let path = dir / y
diff --git a/lib/std/private/strimpl.nim b/lib/std/private/strimpl.nim
index 7d19825f4..6a38cbfd2 100644
--- a/lib/std/private/strimpl.nim
+++ b/lib/std/private/strimpl.nim
@@ -106,7 +106,7 @@ func find*(s, sub: cstring, start: Natural = 0, last = 0): int =
   if sub.len > s.len - start: return -1
   if sub.len == 1: return find(s, sub[0], start, last)
   if last == 0 and s.len > start:
-    let found = c_strstr(s[start].unsafeAddr, sub)
+    let found = c_strstr(cast[cstring](s[start].unsafeAddr), sub)
     if not found.isNil:
       result = cast[ByteAddress](found) -% cast[ByteAddress](s)
     else:
diff --git a/lib/std/private/win_setenv.nim b/lib/std/private/win_setenv.nim
index 9315f3e7e..303889a40 100644
--- a/lib/std/private/win_setenv.nim
+++ b/lib/std/private/win_setenv.nim
@@ -94,9 +94,9 @@ else:
         var buf = newSeq[char](requiredSize + 1)
         let buf2 = buf[0].addr
         if wcstombs(buf2, wideName, csize_t(requiredSize + 1)) != high(csize_t):
-          var ptrToEnv = c_getenv(buf2)
+          var ptrToEnv = c_getenv(cast[cstring](buf2))
           ptrToEnv[0] = '\0'
-          ptrToEnv = c_getenv(buf2)
+          ptrToEnv = c_getenv(cast[cstring](buf2))
           ptrToEnv[1] = '='
 
     # And now, we have to update the outer environment to have a proper empty value.
diff --git a/lib/std/syncio.nim b/lib/std/syncio.nim
index d406c254f..16abc5afe 100644
--- a/lib/std/syncio.nim
+++ b/lib/std/syncio.nim
@@ -467,7 +467,7 @@ proc readLine*(f: File, line: var string): bool {.tags: [ReadIOEffect],
     while true:
       # fixes #9634; this pattern may need to be abstracted as a template if reused;
       # likely other io procs need this for correctness.
-      fgetsSuccess = c_fgets(addr line[pos], sp.cint, f) != nil
+      fgetsSuccess = c_fgets(cast[cstring](addr line[pos]), sp.cint, f) != nil
       if fgetsSuccess: break
       when not defined(nimscript):
         if errno == EINTR:
diff --git a/lib/system.nim b/lib/system.nim
index a8e5824b5..6e16b1189 100644
--- a/lib/system.nim
+++ b/lib/system.nim
@@ -1844,7 +1844,7 @@ proc debugEcho*(x: varargs[typed, `$`]) {.magic: "Echo", noSideEffect,
 when hostOS == "standalone" and defined(nogc):
   proc nimToCStringConv(s: NimString): cstring {.compilerproc, inline.} =
     if s == nil or s.len == 0: result = cstring""
-    else: result = cstring(addr s.data)
+    else: result = cast[cstring](addr s.data)
 
 proc getTypeInfo*[T](x: T): pointer {.magic: "GetTypeInfo", benign.}
   ## Get type information for `x`.
diff --git a/lib/system/dyncalls.nim b/lib/system/dyncalls.nim
index d5ebe3c19..de22f7cbb 100644
--- a/lib/system/dyncalls.nim
+++ b/lib/system/dyncalls.nim
@@ -161,7 +161,7 @@ elif defined(windows) or defined(dos):
         dec(m)
         k = k div 10
         if k == 0: break
-      result = getProcAddress(cast[THINSTANCE](lib), addr decorated)
+      result = getProcAddress(cast[THINSTANCE](lib), cast[cstring](addr decorated))
       if result != nil: return
     procAddrError(name)
 
diff --git a/lib/system/excpt.nim b/lib/system/excpt.nim
index c76be554f..86cfff9cd 100644
--- a/lib/system/excpt.nim
+++ b/lib/system/excpt.nim
@@ -397,9 +397,9 @@ proc reportUnhandledErrorAux(e: ref Exception) {.nodestroy, gcsafe.} =
     xadd(buf, e.name, e.name.len)
     add(buf, "]\n")
     if onUnhandledException != nil:
-      onUnhandledException($buf.addr)
+      onUnhandledException($cast[cstring](buf.addr))
     else:
-      showErrorMessage(buf.addr, L)
+      showErrorMessage(cast[cstring](buf.addr), L)
 
 proc reportUnhandledError(e: ref Exception) {.nodestroy, gcsafe.} =
   if unhandledExceptionHook != nil:
diff --git a/lib/system/repr.nim b/lib/system/repr.nim
index e049d18fa..e47220656 100644
--- a/lib/system/repr.nim
+++ b/lib/system/repr.nim
@@ -17,7 +17,7 @@ proc reprFloat(x: float): string {.compilerproc.} = return $x
 
 proc reprPointer(x: pointer): string {.compilerproc.} =
   result = newString(60)
-  let n = c_sprintf(addr result[0], "%p", x)
+  let n = c_sprintf(cast[cstring](addr result[0]), "%p", x)
   setLen(result, n)
 
 proc reprStrAux(result: var string, s: cstring; len: int) =
diff --git a/lib/system/strmantle.nim b/lib/system/strmantle.nim
index cb67185ab..3c6ac718b 100644
--- a/lib/system/strmantle.nim
+++ b/lib/system/strmantle.nim
@@ -232,7 +232,7 @@ proc nimParseBiggestFloat(s: openArray[char], number: var BiggestFloat,
   t[ti-2] = ('0'.ord + absExponent mod 10).char
   absExponent = absExponent div 10
   t[ti-3] = ('0'.ord + absExponent mod 10).char
-  number = c_strtod(addr t, nil)
+  number = c_strtod(cast[cstring](addr t), nil)
 
 when defined(nimHasInvariant):
   {.pop.} # staticBoundChecks
diff --git a/lib/system/strs_v2.nim b/lib/system/strs_v2.nim
index 74b9e7cd9..e5ab236d2 100644
--- a/lib/system/strs_v2.nim
+++ b/lib/system/strs_v2.nim
@@ -89,7 +89,7 @@ proc cstrToNimstr(str: cstring): NimStringV2 {.compilerRtl.} =
 
 proc nimToCStringConv(s: NimStringV2): cstring {.compilerproc, nonReloadable, inline.} =
   if s.len == 0: result = cstring""
-  else: result = cstring(unsafeAddr s.p.data)
+  else: result = cast[cstring](unsafeAddr s.p.data)
 
 proc appendString(dest: var NimStringV2; src: NimStringV2) {.compilerproc, inline.} =
   if src.len > 0:
diff --git a/lib/system/sysstr.nim b/lib/system/sysstr.nim
index 7655d9004..be32652d8 100644
--- a/lib/system/sysstr.nim
+++ b/lib/system/sysstr.nim
@@ -91,7 +91,7 @@ proc copyStr(s: NimString, start: int): NimString {.compilerproc.} =
 
 proc nimToCStringConv(s: NimString): cstring {.compilerproc, nonReloadable, inline.} =
   if s == nil or s.len == 0: result = cstring""
-  else: result = cstring(addr s.data)
+  else: result = cast[cstring](addr s.data)
 
 proc toNimStr(str: cstring, len: int): NimString {.compilerproc.} =
   result = rawNewStringNoInit(len)
diff --git a/lib/wrappers/openssl.nim b/lib/wrappers/openssl.nim
index edbbd9618..b3fe8a608 100644
--- a/lib/wrappers/openssl.nim
+++ b/lib/wrappers/openssl.nim
@@ -804,10 +804,10 @@ proc md5_File*(file: string): string {.raises: [IOError,Exception].} =
   while (let bytes = f.readChars(buf); bytes > 0):
     discard md5_Update(ctx, buf[0].addr, cast[csize_t](bytes))
 
-  discard md5_Final(buf[0].addr, ctx)
+  discard md5_Final(cast[cstring](buf[0].addr), ctx)
   f.close
 
-  result = hexStr(addr buf)
+  result = hexStr(cast[cstring](addr buf))
 
 proc md5_Str*(str: string): string =
   ## Generate MD5 hash for a string. Result is a 32 character
@@ -824,8 +824,8 @@ proc md5_Str*(str: string): string =
     discard md5_Update(ctx, input[i].addr, cast[csize_t](L))
     i += L
 
-  discard md5_Final(addr res, ctx)
-  result = hexStr(addr res)
+  discard md5_Final(cast[cstring](addr res), ctx)
+  result = hexStr(cast[cstring](addr res))
 
 when defined(nimHasStyleChecks):
   {.pop.}