From 9c932d39fd256dbaed1f89197de35ac2e5810562 Mon Sep 17 00:00:00 2001
From: dkorpel <dkorpel@gmail.com>
Date: Sat, 29 May 2021 14:18:15 +0200
Subject: [PATCH] add return scope to realloc

---
 std/internal/cstring.d | 60 +++++++++++++++++++++++-------------------
 std/internal/memory.d  |  4 +--
 std/uni/package.d      |  2 +-
 3 files changed, 36 insertions(+), 30 deletions(-)

diff --git a/std/internal/cstring.d b/std/internal/cstring.d
index 718305bd2c7..a61ee81cc45 100644
--- a/std/internal/cstring.d
+++ b/std/internal/cstring.d
@@ -145,7 +145,10 @@ if (isSomeChar!To && (isInputRange!From || isSomeString!From) &&
         {
             if (i + 1 == p.length)
             {
-                heapBuffer = trustedRealloc(p, strLength, heapBuffer is null);
+                if (heapBuffer is null)
+                    heapBuffer = trustedReallocStack(p, strLength);
+                else
+                    heapBuffer = trustedRealloc(heapBuffer);
                 p = heapBuffer;
             }
             p[i++] = c;
@@ -269,38 +272,41 @@ private:
     static TempCStringBuffer trustedVoidInit() { TempCStringBuffer res = void; return res; }
 }
 
-private To[] trustedRealloc(To)(scope To[] buf, size_t strLength, bool bufIsOnStack)
+private To[] trustedRealloc(To)(return scope To[] buf)
     @trusted @nogc pure nothrow
 {
     pragma(inline, false);  // because it's rarely called
+    import std.internal.memory : enforceRealloc;
 
-    import std.internal.memory : enforceMalloc, enforceRealloc;
-
-    size_t newlen = buf.length * 3 / 2;
-
-    if (bufIsOnStack)
-    {
-        if (newlen <= strLength)
-            newlen = strLength + 1; // +1 for terminating 0
-        auto ptr = cast(To*) enforceMalloc(newlen * To.sizeof);
-        ptr[0 .. buf.length] = buf[];
-        return ptr[0 .. newlen];
-    }
-    else
+    const size_t newlen = buf.length * 3 / 2;
+    if (buf.length >= size_t.max / (2 * To.sizeof))
     {
-        if (buf.length >= size_t.max / (2 * To.sizeof))
+        version (D_Exceptions)
         {
-            version (D_Exceptions)
-            {
-                import core.exception : onOutOfMemoryError;
-                onOutOfMemoryError();
-            }
-            else
-            {
-                assert(0, "Memory allocation failed");
-            }
+            import core.exception : onOutOfMemoryError;
+            onOutOfMemoryError();
+        }
+        else
+        {
+            assert(0, "Memory allocation failed");
         }
-        auto ptr = cast(To*) enforceRealloc(buf.ptr, newlen * To.sizeof);
-        return ptr[0 .. newlen];
     }
+    auto ptr = cast(To*) enforceRealloc(buf.ptr, newlen * To.sizeof);
+    return ptr[0 .. newlen];
+
+}
+
+private To[] trustedReallocStack(To)(scope To[] buf, size_t strLength)
+    @trusted @nogc pure nothrow
+{
+    pragma(inline, false);  // because it's rarely called
+
+    import std.internal.memory : enforceMalloc;
+
+    size_t newlen = buf.length * 3 / 2;
+    if (newlen <= strLength)
+        newlen = strLength + 1; // +1 for terminating 0
+    auto ptr = cast(To*) enforceMalloc(newlen * To.sizeof);
+    ptr[0 .. buf.length] = buf[];
+    return ptr[0 .. newlen];
 }
diff --git a/std/internal/memory.d b/std/internal/memory.d
index a8b677d4b3b..991cd685b73 100644
--- a/std/internal/memory.d
+++ b/std/internal/memory.d
@@ -42,7 +42,7 @@ void* enforceCalloc()(size_t nmemb, size_t size) @nogc nothrow pure @safe
 }
 
 // ditto
-void* enforceRealloc()(void* ptr, size_t size) @nogc nothrow pure @system
+void* enforceRealloc()(return scope void* ptr, size_t size) @nogc nothrow pure @system
 {
     auto result = fakePureRealloc(ptr, size);
     if (!result) mixin(allocationFailed);
@@ -54,5 +54,5 @@ extern (C) @nogc nothrow pure private
 {
     pragma(mangle, "malloc") void* fakePureMalloc(size_t) @safe;
     pragma(mangle, "calloc") void* fakePureCalloc(size_t nmemb, size_t size) @safe;
-    pragma(mangle, "realloc") void* fakePureRealloc(void* ptr, size_t size) @system;
+    pragma(mangle, "realloc") void* fakePureRealloc(return scope void* ptr, size_t size) @system;
 }
diff --git a/std/uni/package.d b/std/uni/package.d
index b52ba78d7c7..318bcb32a6f 100644
--- a/std/uni/package.d
+++ b/std/uni/package.d
@@ -1819,7 +1819,7 @@ alias sharSwitchLowerBound = sharMethod!switchUniformLowerBound;
         return ptr[0 .. size];
     }
 
-    static T[] realloc(T)(scope T[] arr, size_t size) @trusted
+    static T[] realloc(T)(return scope T[] arr, size_t size) @trusted
     {
         import std.internal.memory : enforceRealloc;
         if (!size)