Fix for bugzilla 2718

std/stream.d

@@ -298,8 +298,8 @@ interface OutputStream {
    * and should only be used in conjunction with read.
    * Throw WriteException on error.
    */
-  void write(char[] s);
-  void write(const(wchar)[] s); /// ditto
+    void write(const(char)[] s);
+    void write(const(wchar)[] s); /// ditto
 
   /***
    * Write a line of text,
@@ -337,8 +337,8 @@ interface OutputStream {
    * Print a formatted string into the stream using printf-style syntax,
    * returning the number of bytes written.
    */
-  size_t vprintf(char[] format, va_list args);
-  size_t printf(char[] format, ...);    /// ditto
+  size_t vprintf(const(char)[] format, va_list args);
+  size_t printf(const(char)[] format, ...);    /// ditto
 
   /***
    * Print a formatted string into the stream using writef-style syntax.
@@ -1077,7 +1077,7 @@ class Stream : InputStream, OutputStream {
   void write(dchar x) { writeExact(&x, x.sizeof); }
 
   // writes a string, together with its length
-  void write(char[] s) {
+  void write(const(char)[] s) {
     write(s.length);
     writeString(s);
   }
@@ -1122,7 +1122,7 @@ class Stream : InputStream, OutputStream {
 
   // writes data to stream using vprintf() syntax,
   // returns number of bytes written
-  size_t vprintf(char[] format, va_list args) {
+  size_t vprintf(const(char)[] format, va_list args) {
     // shamelessly stolen from OutBuffer,
     // by Walter's permission
     char[1024] buffer;
@@ -1155,7 +1155,7 @@ class Stream : InputStream, OutputStream {
 
   // writes data to stream using printf() syntax,
   // returns number of bytes written
-  size_t printf(char[] format, ...) {
+  size_t printf(const(char)[] format, ...) {
     va_list ap;
     ap = cast(va_list) &format;
     ap += format.sizeof;

std/string.d

@@ -215,7 +215,7 @@ unittest
  * $(D s[]) must not contain embedded 0's.
  */
 
-const(char)* toStringz(const(char)[] s)
+immutable(char)* toStringz(const(char)[] s)
 in
 {
     // The assert below contradicts the unittests!
@@ -255,22 +255,29 @@ body
     copy = new char[s.length + 1];
     copy[0..s.length] = s;
     copy[s.length] = 0;
-    return copy.ptr;
-}
-
-// /// Ditto
-// const(char)* toStringz(immutable(char)[] s)
-// {
-//     /* Peek past end of s[], if it's 0, no conversion necessary.
-//      * Note that the compiler will put a 0 past the end of static
-//      * strings, and the storage allocator will put a 0 past the end
-//      * of newly allocated char[]'s.
-//      */
-//     immutable p = &s[0] + s.length;
-//     if (*p == 0)
-//         return s.ptr;
-//     return toStringz(cast(const char[]) s);
-// }
+
+    return assumeUnique(copy).ptr;
+}
+
+/// Ditto
+immutable(char)* toStringz(string s)
+{
+    if (!s) return null;
+    /* Peek past end of s[], if it's 0, no conversion necessary.
+     * Note that the compiler will put a 0 past the end of static
+     * strings, and the storage allocator will put a 0 past the end
+     * of newly allocated char[]'s.
+     */
+    immutable p = s.ptr + s.length;
+    // Is p dereferenceable? A simple test: if the p points to an
+    // address multiple of 4, then conservatively assume the pointer
+    // might be pointing to a new block of memory, which might be
+    // unreadable. Otherwise, it's definitely pointing to valid
+    // memory.
+    if ((cast(size_t) p & 3) && *p == 0)
+        return s.ptr;
+    return toStringz(cast(const char[]) s);
+}
 
 unittest
 {

std/utf.d

@@ -919,6 +919,14 @@ string toUTF8(string s)
 
 /** ditto */
 
+string toUTF8(in char[] s)
+{
+    validate(s);
+    return s.idup;
+}
+
+/** ditto */
+
 string toUTF8(const(wchar)[] s)
 {
     char[] r;