deprecate unsafeAddr; extend addr

changelog.md

@@ -17,6 +17,9 @@
 - `std/sharedstrings` module is removed.
 - Constants `colors.colPaleVioletRed` and `colors.colMediumPurple` changed to match the CSS color standard.
 
+- `addr` is now available for all addressable locations, `unsafeAddr` is deprecated and
+become an alias for `addr`.
+
 ## Standard library additions and changes
 
 - `macros.parseExpr` and `macros.parseStmt` now accept an optional

compiler/isolation_check.nim

@@ -71,7 +71,7 @@ proc isValueOnlyType(t: PType): bool =
 
 proc canAlias*(arg, ret: PType): bool =
   if isValueOnlyType(arg):
-    # can alias only with unsafeAddr(arg.x) and we don't care if it is not safe
+    # can alias only with addr(arg.x) and we don't care if it is not safe
     result = false
   else:
     var marker = initIntSet()

compiler/semmagic.nim

@@ -14,13 +14,8 @@ proc semAddrArg(c: PContext; n: PNode; isUnsafeAddr = false): PNode =
   let x = semExprWithType(c, n)
   if x.kind == nkSym:
     x.sym.flags.incl(sfAddrTaken)
-  if isAssignable(c, x, isUnsafeAddr) notin {arLValue, arLocalLValue}:
-    # Do not suggest the use of unsafeAddr if this expression already is a
-    # unsafeAddr
-    if isUnsafeAddr:
-      localError(c.config, n.info, errExprHasNoAddress)
-    else:
-      localError(c.config, n.info, errExprHasNoAddress & "; maybe use 'unsafeAddr'")
+  if isAssignable(c, x, true) notin {arLValue, arLocalLValue}:
+    localError(c.config, n.info, errExprHasNoAddress)
   result = x
 
 proc semTypeOf(c: PContext; n: PNode): PNode =

doc/manual.rst

@@ -3502,8 +3502,9 @@ location is `T`, the `addr` operator result is of the type `ptr T`. An
 address is always an untraced reference. Taking the address of an object that
 resides on the stack is **unsafe**, as the pointer may live longer than the
 object on the stack and can thus reference a non-existing object. One can get
-the address of variables, but one can't use it on variables declared through
-`let` statements:
+the address of variables. For easier interoperability with other compiled languages
+such as C, retrieving the address of a `let` variable, a parameter,
+or a `for` loop variable can be accomplished too:
 
 .. code-block:: nim
 
@@ -3515,24 +3516,18 @@ the address of variables, but one can't use it on variables declared through
   # --> ref 0x7fff6b71b670 --> 0x10bb81050"Hello"
   echo cast[ptr string](t3)[]
   # --> Hello
-  # The following line doesn't compile:
+  # The following line also works
   echo repr(addr(t1))
-  # Error: expression has no address
-
 
 The unsafeAddr operator
 -----------------------
 
-For easier interoperability with other compiled languages such as C, retrieving
-the address of a `let` variable, a parameter, or a `for` loop variable can
-be accomplished by using the `unsafeAddr` operation:
+The unsafeAddr operator is an alias for the addr operator and is deprecated:
 
 .. code-block:: nim
-
   let myArray = [1, 2, 3]
   foreignProcThatTakesAnAddr(unsafeAddr myArray)
 
-
 Procedures
 ==========
 

doc/manual_experimental.rst

@@ -592,7 +592,7 @@ has `source` as the owner. A path expression `e` is defined recursively:
 - Object field access `e.field` is a path expression.
 - `system.toOpenArray(e, ...)` is a path expression.
 - Pointer dereference `e[]` is a path expression.
-- An address `addr e`, `unsafeAddr e` is a path expression.
+- An address `addr e` is a path expression.
 - A type conversion `T(e)` is a path expression.
 - A cast expression `cast[T](e)` is a path expression.
 - `f(e, ...)` is a path expression if `f`'s return type is a view type.

lib/system.nim

@@ -192,6 +192,13 @@ else:
 
 proc `addr`*[T](x: var T): ptr T {.magic: "Addr", noSideEffect.} =
   ## Builtin `addr` operator for taking the address of a memory location.
+  ## This works even for `let` variables or parameters
+  ## for better interop with C.
+  ##
+  ## .. note:: When you use it to write a wrapper for a C library, you should
+  ## always check that the original library does never write to data behind the
+  ## pointer that is returned from this procedure.
+  ##
   ## Cannot be overloaded.
   ##
   ## See also:
@@ -205,13 +212,13 @@ proc `addr`*[T](x: var T): ptr T {.magic: "Addr", noSideEffect.} =
   ##  echo p[]    # b
   discard
 
-proc unsafeAddr*[T](x: T): ptr T {.magic: "Addr", noSideEffect.} =
+proc unsafeAddr*[T](x: T): ptr T {.magic: "Addr", noSideEffect,
+  deprecated: "'unsafeAddr' is a deprecated alias for 'addr'".} =
   ## Builtin `addr` operator for taking the address of a memory
   ## location. This works even for `let` variables or parameters
-  ## for better interop with C and so it is considered even more
-  ## unsafe than the ordinary `addr <#addr,T>`_.
+  ## for better interop with C.
   ##
-  ## **Note**: When you use it to write a wrapper for a C library, you should
+  ## .. note:: When you use it to write a wrapper for a C library, you should
   ## always check that the original library does never write to data behind the
   ## pointer that is returned from this procedure.
   ##