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- implemented handling for virtual function.

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Syntax-wise I chose to make it as strict as possible to reduce the chance of errors: Virtual base functions must be declared with the 'virtual' keyword, and overrides in child classes with the 'override' keyword. This way any mismatch in parameters that otherwise would cause silent failure will outright produce a compile error.
This commit is contained in:
Christoph Oelckers 2016-11-11 20:05:07 +01:00
commit 72e77a6c65
15 changed files with 222 additions and 47 deletions
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72
src/scripting/zscript/zcc_compile.cpp
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@ -1258,7 +1258,7 @@ bool ZCCCompiler::CompileFields(PStruct *type, TArray<ZCC_VarDeclarator *> &Fiel
PType *fieldtype = DetermineType(type, field, field->Names->Name, field->Type, true, true);
// For structs only allow 'deprecated', for classes exclude function qualifiers.
int notallowed = forstruct? ~ZCC_Deprecated : ZCC_Latent | ZCC_Final | ZCC_Action | ZCC_Static | ZCC_FuncConst | ZCC_Abstract;
int notallowed = forstruct? ~ZCC_Deprecated : ZCC_Latent | ZCC_Final | ZCC_Action | ZCC_Static | ZCC_FuncConst | ZCC_Abstract | ZCC_Virtual | ZCC_Override;
if (field->Flags & notallowed)
{
@ -1894,6 +1894,7 @@ void ZCCCompiler::InitDefaults()
if (!c->Type()->IsDescendantOf(RUNTIME_CLASS(AActor)))
{
if (c->Defaults.Size()) Error(c->cls, "%s: Non-actor classes may not have defaults", c->Type()->TypeName.GetChars());
if (c->Type()->ParentClass) c->Type()->ParentClass->DeriveData(c->Type());
}
else
{
@ -1989,6 +1990,16 @@ void ZCCCompiler::InitFunctions()
for (auto c : Classes)
{
// cannot be done earlier because it requires the parent class to be processed by this code, too.
if (c->Type()->ParentClass != nullptr)
{
if (c->Type()->ParentClass->Virtuals.Size() == 0)
{
// This a VMClass which didn't get processed here.
c->Type()->ParentClass->Virtuals = c->Type()->ParentClass->ParentClass->Virtuals;
}
c->Type()->Virtuals = c->Type()->ParentClass->Virtuals;
}
for (auto f : c->Functions)
{
rets.Clear();
@ -2030,13 +2041,32 @@ void ZCCCompiler::InitFunctions()
if (f->Flags & ZCC_Private) varflags |= VARF_Private;
if (f->Flags & ZCC_Protected) varflags |= VARF_Protected;
if (f->Flags & ZCC_Deprecated) varflags |= VARF_Deprecated;
if (f->Flags & ZCC_Virtual) varflags |= VARF_Virtual;
if (f->Flags & ZCC_Override) varflags |= VARF_Override;
if (f->Flags & ZCC_Action) varflags |= VARF_Action|VARF_Final, implicitargs = 3; // Action implies Final.
if (f->Flags & ZCC_Static) varflags = (varflags & ~VARF_Method) | VARF_Final, implicitargs = 0; // Static implies Final.
if ((f->Flags & (ZCC_Action | ZCC_Static)) == (ZCC_Action | ZCC_Static))
if (varflags & VARF_Override) varflags &= ~VARF_Virtual; // allow 'virtual override'.
// Only one of these flags may be used.
static int exclude[] = { ZCC_Virtual, ZCC_Override, ZCC_Action, ZCC_Static };
static const char * print[] = { "virtual", "override", "action", "static" };
int fc = 0;
FString build;
for (int i = 0; i < 4; i++)
{
Error(f, "%s: Action and Static on the same function is not allowed.", FName(f->Name).GetChars());
if (f->Flags & exclude[i])
{
fc++;
if (build.Len() > 0) build += ", ";
build += print[i];
}
}
if (fc > 1)
{
Error(f, "Invalid combination of qualifiers %s on function %s.", FName(f->Name).GetChars(), build.GetChars() );
varflags |= VARF_Method;
}
if (varflags & VARF_Override) varflags |= VARF_Virtual; // Now that the flags are checked, make all override functions virtual as well.
if (f->Flags & ZCC_Native)
{
@ -2193,7 +2223,41 @@ void ZCCCompiler::InitFunctions()
{
sym->Variants[0].Implementation->DefaultArgs = std::move(argdefaults);
}
// todo: Check inheritance.
if (varflags & VARF_Virtual)
{
if (varflags & VARF_Final)
{
sym->Variants[0].Implementation->Final = true;
}
int vindex = c->Type()->FindVirtualIndex(sym->SymbolName, sym->Variants[0].Proto);
// specifying 'override' is necessary to prevent one of the biggest problem spots with virtual inheritance: Mismatching argument types.
if (varflags & VARF_Override)
{
if (vindex == -1)
{
Error(p, "Attempt to override non-existent virtual function %s", FName(f->Name).GetChars());
}
else
{
auto oldfunc = c->Type()->Virtuals[vindex];
if (oldfunc->Final)
{
Error(p, "Attempt to override final function %s", FName(f->Name).GetChars());
}
c->Type()->Virtuals[vindex] = sym->Variants[0].Implementation;
sym->Variants[0].Implementation->VirtualIndex = vindex;
}
}
else
{
if (vindex != -1)
{
Error(p, "Function %s attempts to override parent function without 'override' qualifier", FName(f->Name).GetChars());
}
sym->Variants[0].Implementation->VirtualIndex = c->Type()->Virtuals.Push(sym->Variants[0].Implementation);
}
}
}
}
}