[Issue 19666] Compiler executes illegal instruction casting array to struct pointer

March 03, 2019

Posted by Basile-z

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Basile-z

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https://issues.dlang.org/show_bug.cgi?id=19666

Basile-z <b2.temp@gmx.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |CTFE
                 CC|                            |b2.temp@gmx.com

--- Comment #1 from Basile-z <b2.temp@gmx.com> ---
This is actually an assertion failure during CTFE:

---
ERROR: This is a compiler bug.
Please report it via https://issues.dlang.org/enter_bug.cgi
with, preferably, a reduced, reproducible example and the information below.
DustMite (https://github.com/CyberShadow/DustMite/wiki) can help with the
reduction.
---
DMD v2.085.0-81-g4a73e58c1-dirty
predefs   DigitalMars Posix linux ELFv1 CRuntime_Glibc CppRuntime_Gcc
LittleEndian D_Version2 all D_SIMD D_InlineAsm_X86_64 X86_64 D_LP64 D_PIC
assert D_ModuleInfo D_Exceptions D_TypeInfo D_HardFloat
binary    dmd/generated/linux/debug/64/dmd
version   v2.085.0-81-g4a73e58c1-dirty
config    dmd.conf
DFLAGS    -I./../../../../../druntime/import -I./../../../../../phobos
-L-L./../../../../../phobos/generated/linux/debug/64 -L--export-dynamic -fPIC
---
core.exception.AssertError@dmd/ctfeexpr.d(1685): Assertion failure
----------------
??:? _d_assertp [0x7bc0a8]
dmd/ctfeexpr.d:1685 void dmd.ctfeexpr.assignInPlace(dmd.expression.Expression,
dmd.expression.Expression) [0x56f0b8]
dmd/dinterpret.d:4035 _ZN11Interpreter14assignToLvalueEP6BinExpP10ExpressionS3_
[0x58fd57]
dmd/dinterpret.d:3916 void
dmd.dinterpret.Interpreter.interpretAssignCommon(dmd.expression.BinExp,
dmd.expression.UnionExp function(ref const(dmd.globals.Loc), dmd.mtype.Type,
dmd.expression.Expression, dmd.expression.Expression)*, int) [0x58f6ce]
dmd/dinterpret.d:4495 _ZN11Interpreter5visitEP9AssignExp [0x5917f4]
dmd/expression.d:5718 _ZN9AssignExp6acceptEP7Visitor [0x5ee96d]
dmd/dinterpret.d:6491 dmd.expression.Expression
dmd.dinterpret.interpret(dmd.expression.UnionExp*, dmd.expression.Expression,
dmd.dinterpret.InterState*, dmd.dinterpret.CtfeGoal) [0x597767]
dmd/dinterpret.d:1096 _ZN11Interpreter5visitEP12ExpStatement [0x587610]
dmd/statement.d:738 _ZN12ExpStatement6acceptEP7Visitor [0x68e051]
dmd/dinterpret.d:6523 dmd.expression.Expression
dmd.dinterpret.interpret(dmd.expression.UnionExp*, dmd.statement.Statement,
dmd.dinterpret.InterState*) [0x597846]
dmd/dinterpret.d:1114 _ZN11Interpreter5visitEP17CompoundStatement [0x5876d5]
dmd/statement.d:935 _ZN17CompoundStatement6acceptEP7Visitor [0x68e8b1]
dmd/dinterpret.d:6523 dmd.expression.Expression
dmd.dinterpret.interpret(dmd.expression.UnionExp*, dmd.statement.Statement,
dmd.dinterpret.InterState*) [0x597846]
dmd/dinterpret.d:1114 _ZN11Interpreter5visitEP17CompoundStatement [0x5876d5]
dmd/statement.d:935 _ZN17CompoundStatement6acceptEP7Visitor [0x68e8b1]
dmd/dinterpret.d:6523 dmd.expression.Expression
dmd.dinterpret.interpret(dmd.expression.UnionExp*, dmd.statement.Statement,
dmd.dinterpret.InterState*) [0x597846]
dmd/dinterpret.d:966 dmd.expression.Expression
dmd.dinterpret.interpretFunction(dmd.expression.UnionExp*,
dmd.func.FuncDeclaration, dmd.dinterpret.InterState*,
dmd.root.array.Array!(dmd.expression.Expression).Array*,
dmd.expression.Expression) [0x58721d]
dmd/dinterpret.d:5035 _ZN11Interpreter5visitEP7CallExp [0x592cac]
dmd/expression.d:4892 _ZN7CallExp6acceptEP7Visitor [0x5ecfe5]
dmd/dinterpret.d:6491 dmd.expression.Expression
dmd.dinterpret.interpret(dmd.expression.UnionExp*, dmd.expression.Expression,
dmd.dinterpret.InterState*, dmd.dinterpret.CtfeGoal) [0x597767]
dmd/dinterpret.d:6501 dmd.expression.Expression
dmd.dinterpret.interpret(dmd.expression.Expression, dmd.dinterpret.InterState*,
dmd.dinterpret.CtfeGoal) [0x5977c1]
dmd/dinterpret.d:87 dmd.expression.Expression
dmd.dinterpret.ctfeInterpret(dmd.expression.Expression) [0x585001]
dmd/expression.d:1548 _ZN10Expression13ctfeInterpretEv [0x5e4f34]
dmd/initsem.d:393 dmd.init.Initializer
dmd.initsem.initializerSemantic(dmd.init.Initializer, dmd.dscope.Scope*,
dmd.mtype.Type, dmd.init.NeedInterpret).visitExp(dmd.init.ExpInitializer)
[0x631552]
dmd/initsem.d:523
_Z19initializerSemanticP11InitializerP5ScopeP4Type13NeedInterpret [0x62fee2]
dmd/dsymbolsem.d:1274 _ZN22DsymbolSemanticVisitor5visitEP14VarDeclaration
[0x5bb8f3]
dmd/declaration.d:1640 _ZN14VarDeclaration6acceptEP7Visitor [0x5810c1]
dmd/dsymbolsem.d:365 _Z15dsymbolSemanticP7DsymbolP5Scope [0x5b8b84]
dmd/dsymbolsem.d:1979 void
dmd.dsymbolsem.DsymbolSemanticVisitor.visit(dmd.dmodule.Module).__lambda2!(dmd.dsymbol.Dsymbol).__lambda2(dmd.dsymbol.Dsymbol)
[0x5bdf97]
dmd/dsymbol.d:97 void
dmd.dsymbol.foreachDsymbol(dmd.root.array.Array!(dmd.dsymbol.Dsymbol).Array*,
void delegate(dmd.dsymbol.Dsymbol)) [0x5b2f8f]
dmd/dsymbolsem.d:1976 _ZN22DsymbolSemanticVisitor5visitEP6Module [0x5bdf23]
dmd/dmodule.d:1290 _ZN6Module6acceptEP7Visitor [0x5a10ed]
dmd/dsymbolsem.d:365 _Z15dsymbolSemanticP7DsymbolP5Scope [0x5b8b84]
dmd/mars.d:560 int dmd.mars.tryMain(ulong, const(char)**, ref
dmd.globals.Param) [0x65628e]
dmd/mars.d:859 _Dmain [0x657838]

--

https://issues.dlang.org/show_bug.cgi?id=19666

Basile-z <b2.temp@gmx.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |b2.temp@gmx.com
            Summary|Compiler executes illegal   |Implicit cast from static
                   |instruction casting array   |array to its .ptr not
                   |to struct pointer           |properly rejected during
                   |                            |CTFE

--- Comment #3 from Basile-z <b2.temp@gmx.com> ---
my last comment is wrong, the problem is that implicit conv from static array to its .ptr is not implemented correctly in the CTFE engine.

The expected error happens when doing the cast explicitly:

```d
struct StoreAny {
    ubyte[16] store;
    this(T)(T value) {
        *(cast(T*) store.ptr) = value;
    }
}

struct SomeStruct {}
enum StoreAny someEnum = StoreAny(SomeStruct());
```

> a.d:4:20: Error: reinterpreting cast from `ubyte*` to `SomeStruct*` is not supported in CTFE

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