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Skip over return parameters for return destination #12601

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23 changes: 15 additions & 8 deletions src/dmd/escape.d
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Original file line number Diff line number Diff line change
Expand Up @@ -597,10 +597,10 @@ bool checkAssignEscape(Scope* sc, Expression e, bool gag)
(va.storage_class & (STC.ref_ | STC.out_) || va.type.toBasetype().ty == Tclass);
if (log && vaIsRef) printf("va is ref `%s`\n", va.toChars());

/* Determine if va is the first parameter, through which other 'return' parameters
/* Determine if va is the first non-return parameter, through which other 'return' parameters
* can be assigned.
*/
bool isFirstRef()
bool isReturnDest()
{
if (!vaIsRef)
return false;
Expand All @@ -613,13 +613,20 @@ bool checkAssignEscape(Scope* sc, Expression e, bool gag)
return false;
if (va == fd.vthis)
return true;
if (fd.parameters && fd.parameters.dim && (*fd.parameters)[0] == va)
return true;
if (fd.parameters)
{
foreach (i, v; *fd.parameters) {
if (v == va)
return true;
if (!(v.storage_class & STC.return_))
return false;
}
}
}
return false;
}
const bool vaIsFirstRef = isFirstRef();
if (log && vaIsFirstRef) printf("va is first ref `%s`\n", va.toChars());
const bool vaIsReturnDest = isReturnDest();
if (log && vaIsReturnDest) printf("va is first ref `%s`\n", va.toChars());

bool result = false;
foreach (VarDeclaration v; er.byvalue)
Expand All @@ -643,7 +650,7 @@ bool checkAssignEscape(Scope* sc, Expression e, bool gag)
continue;
}

if (vaIsFirstRef &&
if (vaIsReturnDest &&
(v.isScope() || (v.storage_class & STC.maybescope)) &&
!(v.storage_class & STC.return_) &&
v.isParameter() &&
Expand All @@ -659,7 +666,7 @@ bool checkAssignEscape(Scope* sc, Expression e, bool gag)

if (v.isScope())
{
if (vaIsFirstRef && v.isParameter() && v.storage_class & STC.return_)
if (vaIsReturnDest && v.isParameter() && v.storage_class & STC.return_)
{
if (va.isScope())
continue;
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13 changes: 12 additions & 1 deletion test/fail_compilation/test19097.d
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Original file line number Diff line number Diff line change
@@ -1,7 +1,8 @@
/* REQUIRED_ARGS: -dip1000
* TEST_OUTPUT:
---
fail_compilation/test19097.d(35): Error: scope variable `s` may not be returned
fail_compilation/test19097.d(25): Error: scope variable `p` assigned to `r` with longer lifetime
fail_compilation/test19097.d(46): Error: scope variable `s` may not be returned
---
*/

Expand All @@ -14,6 +15,16 @@ void betty(ref scope int* r, return scope int* p)
r = p;
}

void tabby(return scope int* p, ref scope int* r)
{
r = p;
}

void kitty(return scope int* p, int intermediate, ref scope int* r)
{
r = p;
}

void freddy(out scope int* r, return scope int* p)
{
r = p;
Expand Down