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Fix 23767 - ImportC: ternary with null constant has wrong pointer type #14980

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Merged
RazvanN7 merged 1 commit into from
Mar 13, 2023
Merged

Fix 23767 - ImportC: ternary with null constant has wrong pointer type #14980

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23 changes: 23 additions & 0 deletions compiler/src/dmd/expressionsem.d
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Original file line number Diff line number Diff line change
Expand Up @@ -12319,6 +12319,29 @@ private extern (C++) final class ExpressionSemanticVisitor : Visitor

Type t1 = exp.e1.type;
Type t2 = exp.e2.type;

// https://issues.dlang.org/show_bug.cgi?id=23767
// `cast(void*) 0` should be treated as `null` so the ternary expression
// gets the pointer type of the other branch
if (sc.flags & SCOPE.Cfile)
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@maxhaton maxhaton Mar 12, 2023

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Is there a way to change the way the types are merged rather than rewriting them? Not sure if you have the scope available but you could always just have a different function for finding the common types of C.

The C behaviour (in a sense) was almost what D used to do before I fixed it a while back.

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@dkorpel dkorpel Mar 12, 2023

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void* + T* merges to void* in general, both in C and D, only in C there is special treatment when the void* is the NULL constant

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@maxhaton maxhaton Mar 13, 2023

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Previously it went to T* until I fixed it (I think ldc 1.30 still has this bug)

Could potentially use TypeNull

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@dkorpel dkorpel Mar 13, 2023

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I am rewriting (void*)0 to use TypeNull

{
static void rewriteCNull(ref Expression e, ref Type t)
{
if (!t.isTypePointer())
return;
if (auto ie = e.optimize(WANTvalue).isIntegerExp())
{
if (ie.getInteger() == 0)
{
e = new NullExp(e.loc, Type.tnull);
t = Type.tnull;
}
}
}
rewriteCNull(exp.e1, t1);
rewriteCNull(exp.e2, t2);
}

if (t1.ty == Tnoreturn)
{
exp.type = t2;
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11 changes: 11 additions & 0 deletions compiler/test/compilable/ctests2.c
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Expand Up @@ -195,3 +195,14 @@ _Static_assert(sizeof(testTypeofB) == sizeof(short), "17");
void *c23752 = &*((void*)(0));

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

// https://issues.dlang.org/show_bug.cgi?id=23767
const int arr23767[4];
void f23767(void)
{
int x = *(0 ? (void*)0 : arr23767);
int y = *(1 ? arr23767 : (void*)(3-3));
int* p = (1 ? (void*)0 : (void*)0);
}

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