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DIP29: make dup functions pure #3364

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74 changes: 47 additions & 27 deletions src/cast.c
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Original file line number Diff line number Diff line change
Expand Up @@ -768,33 +768,6 @@ MATCH implicitConvTo(Expression *e, Type *t)
return;
}

/* The result of arr.dup and arr.idup can be unique essentially.
* So deal with this case specially.
*/
if (!e->f && e->e1->op == TOKvar && ((VarExp *)e->e1)->var->ident == Id::adDup &&
t->toBasetype()->ty == Tarray)
{
assert(e->type->toBasetype()->ty == Tarray);
assert(e->arguments->dim == 2);
Expression *eorg = (*e->arguments)[1];
Type *tn = t->nextOf();
if (e->type->nextOf()->implicitConvTo(tn) < MATCHconst)
{
/* If the operand is an unique array literal, then allow conversion.
*/
if (eorg->op != TOKarrayliteral)
return;
Expressions *elements = ((ArrayLiteralExp *)eorg)->elements;
for (size_t i = 0; i < elements->dim; i++)
{
if (!(*elements)[i]->implicitConvTo(tn))
return;
}
}
result = e->type->immutableOf()->implicitConvTo(t);
return;
}

/* Conversion is 'const' conversion if:
* 1. function is pure (weakly pure is ok)
* 2. implicit conversion only fails because of mod bits
Expand All @@ -814,6 +787,51 @@ MATCH implicitConvTo(Expression *e, Type *t)
if (e->type->immutableOf()->implicitConvTo(t->immutableOf()) == MATCHnomatch)
return;

/* adDup() is called to implement arr.dup or arr.idup
* We know that it makes a copy of an array. So it is not necessary
* to check first level, only second level, to see if convertible, because
* we know the first level of the return value will be unique.
*/
bool isdup = false;
if (!e->f && e->e1->op == TOKvar && ((VarExp *)e->e1)->var->ident == Id::adDup &&
t->toBasetype()->ty == Tarray)
{
assert(e->type->toBasetype()->ty == Tarray);
assert(e->arguments->dim == 2);
isdup = true; // so we only check eorg later

Expression *eorg = (*e->arguments)[1];
Type *tnb = t->nextOf()->toBasetype();

Type *typen = e->type->nextOf();

/* If the operand is an array literal, then we can look at the
* array literal elements to do second level conversion check.
*/
if (eorg->op == TOKarrayliteral)
{
Expressions *elements = ((ArrayLiteralExp *)eorg)->elements;
for (size_t i = 0; i < elements->dim; i++)
{
if ((*elements)[i]->implicitConvTo(tnb) == MATCHnomatch)
return;
}
result = MATCHconst;
return;
}

if (typen->implicitConvTo(tnb) >= MATCHconst)
{
result = MATCHconst;
return;
}

/* Treat as regular pure function, i.e. if arguments are unique we can
* allow the conversion. But only check second arg, since we know that
* first arg won't be part of the return value.
*/
}

/* Get mod bits of what we're converting to
*/
Type *tb = t->toBasetype();
Expand Down Expand Up @@ -855,6 +873,8 @@ MATCH implicitConvTo(Expression *e, Type *t)
}
continue;
}
if (isdup)
i = 1; // for adDup, only check eorg for uniqueness
Expression *earg = (*e->arguments)[i];
Type *targ = earg->type->toBasetype();
#if LOG
Expand Down
4 changes: 2 additions & 2 deletions src/declaration.h
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Expand Up @@ -674,8 +674,8 @@ class FuncDeclaration : public Declaration
Statement *mergeFensure(Statement *, Identifier *oid);
Parameters *getParameters(int *pvarargs);

static FuncDeclaration *genCfunc(Parameters *args, Type *treturn, const char *name);
static FuncDeclaration *genCfunc(Parameters *args, Type *treturn, Identifier *id);
static FuncDeclaration *genCfunc(Parameters *args, Type *treturn, const char *name, StorageClass stc = 0);
static FuncDeclaration *genCfunc(Parameters *args, Type *treturn, Identifier *id, StorageClass stc = 0);

Symbol *toThunkSymbol(int offset); // thunk version
void toObjFile(int multiobj); // compile to .obj file
Expand Down
10 changes: 6 additions & 4 deletions src/func.c
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Expand Up @@ -3684,12 +3684,14 @@ bool FuncDeclaration::addPostInvariant()
* Generate a FuncDeclaration for a runtime library function.
*/

FuncDeclaration *FuncDeclaration::genCfunc(Parameters *args, Type *treturn, const char *name)
FuncDeclaration *FuncDeclaration::genCfunc(Parameters *args, Type *treturn, const char *name,
StorageClass stc)
{
return genCfunc(args, treturn, Lexer::idPool(name));
return genCfunc(args, treturn, Lexer::idPool(name), stc);
}

FuncDeclaration *FuncDeclaration::genCfunc(Parameters *args, Type *treturn, Identifier *id)
FuncDeclaration *FuncDeclaration::genCfunc(Parameters *args, Type *treturn, Identifier *id,
StorageClass stc)
{
FuncDeclaration *fd;
TypeFunction *tf;
Expand All @@ -3711,7 +3713,7 @@ FuncDeclaration *FuncDeclaration::genCfunc(Parameters *args, Type *treturn, Iden
}
else
{
tf = new TypeFunction(args, treturn, 0, LINKc);
tf = new TypeFunction(args, treturn, 0, LINKc, stc);
fd = new FuncDeclaration(Loc(), Loc(), id, STCstatic, tf);
fd->protection = PROTpublic;
fd->linkage = LINKc;
Expand Down
3 changes: 2 additions & 1 deletion src/mtype.c
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Expand Up @@ -3802,7 +3802,8 @@ Expression *TypeArray::dotExp(Scope *sc, Expression *e, Identifier *ident, int f
Parameters* args = new Parameters;
args->push(new Parameter(STCin, Type::dtypeinfo->type, NULL, NULL));
args->push(new Parameter(STCin, Type::tvoid->arrayOf(), NULL, NULL));
adDup_fd = FuncDeclaration::genCfunc(args, Type::tvoid->arrayOf(), Id::adDup);
adDup_fd = FuncDeclaration::genCfunc(args, Type::tvoid->arrayOf(), Id::adDup,
STCpure | STCtrusted);
}
fd = adDup_fd;
} else {
Expand Down
21 changes: 21 additions & 0 deletions test/runnable/implicit.d
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Expand Up @@ -161,6 +161,26 @@ void testDIP29_4()

/***********************************/

int[] test6(int[] a) pure @safe nothrow
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@MartinNowak MartinNowak Mar 14, 2014

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nothrow seems to fail here

{
return a.dup;
}

/***********************************/

int*[] pureFoo() pure { return null; }


void testDIP29_5() pure
{
{ char[] s; immutable x = s.dup; }
{ immutable x = (cast(int*[])null).dup; }
{ immutable x = pureFoo(); }
{ immutable x = pureFoo().dup; }
}

/***********************************/

void main()
{
test1();
Expand All @@ -172,6 +192,7 @@ void main()
testDIP29_2();
testDIP29_3();
testDIP29_4();
testDIP29_5();

writefln("Success");
}