Merge pull request #2228 from n8sh/hash-nogc

Fix Issue 19009 - core.internal.hash.hashOf default hash (absent `toHash`) should be `@nogc`
merged-on-behalf-of: Steven Schveighoffer <schveiguy@users.noreply.github.com>

Author: dlang-bot

src/core/internal/convert.d

@@ -10,13 +10,36 @@
 module core.internal.convert;
 import core.internal.traits : Unqual;
 
-@trusted pure nothrow
+/+
+A @nogc function can allocate memory during CTFE.
++/
+@nogc nothrow pure @trusted
+private ubyte[] ctfe_alloc()(size_t n)
+{
+    if (!__ctfe)
+    {
+        assert(0, "CTFE only");
+    }
+    else
+    {
+        static ubyte[] alloc(size_t x) nothrow pure
+        {
+            if (__ctfe) // Needed to prevent _d_newarray from appearing in compiled prorgam.
+                return new ubyte[x];
+            else
+                assert(0);
+        }
+        return (cast(ubyte[] function(size_t) @nogc nothrow pure) &alloc)(n);
+    }
+}
+
+@trusted pure nothrow @nogc
 const(ubyte)[] toUbyte(T)(ref T val) if(is(Unqual!T == float) || is(Unqual!T == double) || is(Unqual!T == real) ||
                                         is(Unqual!T == ifloat) || is(Unqual!T == idouble) || is(Unqual!T == ireal))
 {
     static const(ubyte)[] reverse_(const(ubyte)[] arr)
     {
-        ubyte[] buff = new ubyte[arr.length];
+        ubyte[] buff = ctfe_alloc(arr.length);
         foreach(k, v; arr)
         {
             buff[$-k-1] = v;
@@ -31,7 +54,7 @@ const(ubyte)[] toUbyte(T)(ref T val) if(is(Unqual!T == float) || is(Unqual!T ==
         uint exp = parsed.exponent;
         uint sign = parsed.sign;
 
-        ubyte[T.sizeof] buff;
+        ubyte[] buff = ctfe_alloc(T.sizeof);
         size_t off_bytes = 0;
         size_t off_bits  = 0;
 
@@ -60,7 +83,7 @@ const(ubyte)[] toUbyte(T)(ref T val) if(is(Unqual!T == float) || is(Unqual!T ==
 
         version(LittleEndian)
         {
-            return buff.dup;
+            return buff;
         }
         else
         {
@@ -73,13 +96,13 @@ const(ubyte)[] toUbyte(T)(ref T val) if(is(Unqual!T == float) || is(Unqual!T ==
     }
 }
 
-@safe pure nothrow
+@safe pure nothrow @nogc
 private Float parse(bool is_denormalized = false, T)(T x) if(is(Unqual!T == ifloat) || is(Unqual!T == idouble) || is(Unqual!T == ireal))
 {
     return parse(x.im);
 }
 
-@safe pure nothrow
+@safe pure nothrow @nogc
 private Float parse(bool is_denormalized = false, T:real)(T x_) if(floatFormat!T != FloatFormat.Real80)
 {
     Unqual!T x = x_;
@@ -116,7 +139,7 @@ private Float parse(bool is_denormalized = false, T:real)(T x_) if(floatFormat!T
     return Float(mant, exp, sign);
 }
 
-@safe pure nothrow
+@safe pure nothrow @nogc
 private Float parse(bool _ = false, T:real)(T x_) if(floatFormat!T == FloatFormat.Real80)
 {
     Unqual!T x = x_;
@@ -228,10 +251,10 @@ private template FloatTraits(T) if(floatFormat!T == FloatFormat.Quadruple) //Uns
 }
 
 
-@safe pure nothrow
+@safe pure nothrow @nogc
 private real binPow2(int pow)
 {
-    static real binPosPow2(int pow) @safe pure nothrow
+    static real binPosPow2(int pow) @safe pure nothrow @nogc
     {
         assert(pow > 0);
 
@@ -256,13 +279,13 @@ private real binPow2(int pow)
 
 
 //Need in CTFE, because CTFE float and double expressions computed more precisely that run-time expressions.
-@safe pure nothrow
+@safe pure nothrow @nogc
 private ulong shiftrRound(ulong x)
 {
     return (x >> 1) + (x & 1);
 }
 
-@safe pure nothrow
+@safe pure nothrow @nogc
 private uint binLog2(T)(T x)
 {
     assert(x > 0);
@@ -290,7 +313,7 @@ private uint binLog2(T)(T x)
     return max;
 }
 
-@safe pure nothrow
+@safe pure nothrow @nogc
 private ulong denormalizedMantissa(T)(T x) if(floatFormat!T == FloatFormat.Real80)
 {
     x *= 2.0L^^FloatTraits!T.MANTISSA;
@@ -299,7 +322,7 @@ private ulong denormalizedMantissa(T)(T x) if(floatFormat!T == FloatFormat.Real8
     return fl.mantissa >> pow;
 }
 
-@safe pure nothrow
+@safe pure nothrow @nogc
 private ulong denormalizedMantissa(T)(T x) if(floatFormat!T != FloatFormat.Real80)
 {
     x *= 2.0L^^FloatTraits!T.MANTISSA;
@@ -475,21 +498,23 @@ template floatFormat(T) if(is(T:real) || is(T:ireal))
 }
 
 //  all toUbyte functions must be evaluable at compile time
-@trusted pure nothrow
+@trusted pure nothrow @nogc
 const(ubyte)[] toUbyte(T)(T[] arr) if (T.sizeof == 1)
 {
     return cast(const(ubyte)[])arr;
 }
 
-@trusted pure nothrow
+@trusted pure nothrow @nogc
 const(ubyte)[] toUbyte(T)(T[] arr) if ((is(typeof(toUbyte(arr[0])) == const(ubyte)[])) && (T.sizeof > 1))
 {
     if (__ctfe)
     {
-        const(ubyte)[] ret;
+        ubyte[] ret = ctfe_alloc(T.sizeof * arr.length);
+        size_t offset = 0;
         foreach (cur; arr)
         {
-            ret ~= toUbyte(cur);
+            ret[offset .. offset + T.sizeof] = toUbyte(cur)[0 .. T.sizeof];
+            offset += T.sizeof;
         }
         return ret;
     }
@@ -499,14 +524,16 @@ const(ubyte)[] toUbyte(T)(T[] arr) if ((is(typeof(toUbyte(arr[0])) == const(ubyt
     }
 }
 
-@trusted pure nothrow
+@trusted pure nothrow @nogc
 const(ubyte)[] toUbyte(T)(ref T val) if (__traits(isIntegral, T) && !is(T == enum))
 {
     static if (T.sizeof == 1)
     {
         if (__ctfe)
         {
-            return cast(const(ubyte)[])[val];
+            ubyte[] result = ctfe_alloc(1);
+            result[0] = cast(ubyte) val;
+            return result;
         }
         else
         {
@@ -515,7 +542,7 @@ const(ubyte)[] toUbyte(T)(ref T val) if (__traits(isIntegral, T) && !is(T == enu
     }
     else if (__ctfe)
     {
-        ubyte[T.sizeof] tmp;
+        ubyte[] tmp = ctfe_alloc(T.sizeof);
         Unqual!T val_ = val;
         for (size_t i = 0; i < T.sizeof; ++i)
         {
@@ -525,30 +552,35 @@ const(ubyte)[] toUbyte(T)(ref T val) if (__traits(isIntegral, T) && !is(T == enu
             tmp[idx] = cast(ubyte)(val_&0xff);
             val_ >>= 8;
         }
-        return tmp[].dup;
+        return tmp;
     }
     else
     {
         return (cast(const(ubyte)*)(&val))[0 .. T.sizeof];
     }
 }
 
-@trusted pure nothrow
+@trusted pure nothrow @nogc
 const(ubyte)[] toUbyte(T)(ref T val) if (is(Unqual!T == cfloat) || is(Unqual!T == cdouble) ||is(Unqual!T == creal))
 {
     if (__ctfe)
     {
         auto re = val.re;
         auto im = val.im;
-        return (re.toUbyte() ~ im.toUbyte());
+        auto a = re.toUbyte();
+        auto b = im.toUbyte();
+        ubyte[] result = ctfe_alloc(a.length + b.length);
+        result[0 .. a.length] = a[0 .. a.length];
+        result[a.length .. $] = b[0 .. b.length];
+        return result;
     }
     else
     {
         return (cast(const(ubyte)*)&val)[0 .. T.sizeof];
     }
 }
 
-@trusted pure nothrow
+@trusted pure nothrow @nogc
 const(ubyte)[] toUbyte(T)(ref T val) if (is(T == enum) && is(typeof(toUbyte(cast(V)val)) == const(ubyte)[]))
 {
     if (__ctfe)
@@ -605,12 +637,12 @@ private bool isNonReferenceStruct(T)() if (is(T == struct) || is(T == union))
     return true;
 }
 
-@trusted pure nothrow
+@trusted pure nothrow @nogc
 const(ubyte)[] toUbyte(T)(ref T val) if (is(T == struct) || is(T == union))
 {
     if (__ctfe)
     {
-        ubyte[T.sizeof] bytes;
+        ubyte[] bytes = ctfe_alloc(T.sizeof);
         foreach (key, cur; val.tupleof)
         {
             alias CUR_TYPE = typeof(cur);
@@ -629,7 +661,7 @@ const(ubyte)[] toUbyte(T)(ref T val) if (is(T == struct) || is(T == union))
                 assert(0, "Unable to compute byte representation of "~typeof(CUR_TYPE).stringof~" field at compile time");
             }
         }
-        return bytes[].dup;
+        return bytes;
     }
     else
     {

src/core/internal/hash.d

@@ -72,14 +72,14 @@ if (!is(T == enum) && !is(T : typeof(null)) && is(T S: S[]) && !__traits(isStati
     const _ = hashOf("abc");
 }
 
-nothrow pure @system unittest
+@nogc nothrow pure @system unittest
 {
     void*[] val;
     const _ = hashOf(val); // Check a PR doesn't break this.
 }
 
 //arithmetic type hash
-@trusted nothrow pure
+@trusted @nogc nothrow pure
 size_t hashOf(T)(auto ref T val, size_t seed = 0) if (!is(T == enum) && __traits(isArithmetic, T))
 {
     static if(__traits(isFloating, val))
@@ -94,14 +94,14 @@ size_t hashOf(T)(auto ref T val, size_t seed = 0) if (!is(T == enum) && __traits
 }
 
 //typeof(null) hash. CTFE supported
-@trusted nothrow pure
+@trusted @nogc nothrow pure
 size_t hashOf(T)(auto ref T val, size_t seed = 0) if (!is(T == enum) && is(T : typeof(null)))
 {
     return hashOf(cast(void*)null, seed);
 }
 
 //Pointers hash. CTFE unsupported if not null
-@trusted nothrow pure
+@trusted @nogc nothrow pure
 size_t hashOf(T)(auto ref T val, size_t seed = 0)
 if (!is(T == enum) && is(T V : V*) && !is(T : typeof(null))
     && !is(T == struct) && !is(T == class) && !is(T == union))
@@ -155,7 +155,7 @@ nothrow pure @safe unittest // issue 18925
 }
 
 //delegate hash. CTFE unsupported
-@trusted nothrow pure
+@trusted @nogc nothrow pure
 size_t hashOf(T)(auto ref T val, size_t seed = 0) if (!is(T == enum) && is(T == delegate))
 {
     assert(!__ctfe, "unable to compute hash of "~T.stringof);