RTInfo generation can fail for structs defined in imported modules

[dlangBugzillaToGithub]

Rainer Schuetze (@rainers) reported this on 2013-06-22T01:34:11Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=10442

CC List

• Mike Franklin

Description

The current default implementation for template RTInfo always sets the value 0x12345678, so this should work:

////////////////
module s;

struct S
{
	int x;
	void* p;
}

///////////////
module test;

import s;

struct T
{
	int x;
	void* p;
}

void main()
{
	assert(typeid(T).rtInfo == cast(void*)0x12345678); // ok
	assert(typeid(S).rtInfo == cast(void*)0x12345678); // fails
}

////////////////
but the second assertion triggers if compiled with

dmd test.d

If you add s.d to the command line, it does not fail.

[dlangBugzillaToGithub]

r.sagitario commented on 2013-06-22T01:39:46Z

This is not restricted to the typeid expression, but also happens for other operations like array appending. I suspect it happens if it is only the backend that is requesting the type info, and then, AggregateDeclaration::semantic3 is never run.

[dlangBugzillaToGithub]

r.sagitario commented on 2013-11-30T02:01:09Z

https://github.com/D-Programming-Language/dmd/pull/2480

[dlangBugzillaToGithub]

k.hara.pg commented on 2014-09-07T12:22:53Z

(In reply to Rainer Schuetze from comment #0)
> The current default implementation for template RTInfo always sets the value
> 0x12345678, so this should work:
> 
> ////////////////
> module s;
> 
> struct S
> {
> 	int x;
> 	void* p;
> }
> 
> ///////////////
> module test;
> 
> import s;
> 
> struct T
> {
> 	int x;
> 	void* p;
> }
> 
> void main()
> {
> 	assert(typeid(T).rtInfo == cast(void*)0x12345678); // ok
> 	assert(typeid(S).rtInfo == cast(void*)0x12345678); // fails
> }
> 
> ////////////////
> but the second assertion triggers if compiled with
> 
> dmd test.d

I think the typeid(S) object should not be generated when s.d is not directly compiled. IOW, `dmd test.d` should cause link failure.

I implemented the behavior in:
https://github.com/D-Programming-Language/dmd/pull/3958

[dlangBugzillaToGithub]

r.sagitario commented on 2017-12-24T09:11:11Z

still happens in dmd 2.077

[dlangBugzillaToGithub]

slavo5150 commented on 2018-01-30T02:34:14Z

The following example results in an assertion failure:

struct T
{
    int x;
    void* p;
}

void main()
{
    assert(typeid(T).rtInfo == cast(void*)0x12345678); // Fail
}


However, the following passes:

struct T
{
    int x;
    void* p;
}

void main()
{
    assert(typeid(T).rtInfo is null);
}

This is consistent with what I see in the runtime:  https://github.com/dlang/druntime/blob/544946df1c68727d84cdee11502b244bde0bc22e/src/object.d#L3419

So, I don't understand what the problem is and what the result should be.

[dlangBugzillaToGithub]

r.sagitario commented on 2018-01-30T07:49:31Z

The definition of RTInfo(T) in object.d has changed since 2013 from 0x12345678 to null.

The test in https://github.com/dlang/dmd/pull/2480 verifies that https://github.com/dlang/dmd/blob/master/src/dmd/todt.d#L1394 doesn't use the fallback if no RTInfo has been evaluated (which writes 1 if the struct contains pointers).

[dlangBugzillaToGithub]

dlang-bot commented on 2020-09-09T07:10:56Z

@rainers updated dlang/dmd pull request #2480 "fix issues #10442: no or incomplete RTInfo" fixing this issue:

- fix issue 10442: predict type info references in glue layer

- add test case for issue 10442

https://github.com/dlang/dmd/pull/2480