Remove error for asm statements in a nothrow function

[ibuclaw]

From discussion:
http://forum.dlang.org/post/m02c7p$226e$1@digitalmars.com

And this check is already impossible to hit because of:
https://github.com/D-Programming-Language/dmd/blob/master/src/func.c#L1778

There's already a test for this in: test/compilable/test11471.d - kinda, but druntime already depends on asm statements not causing this error in nothrow functions.

https://github.com/D-Programming-Language/druntime/blob/dbf3ff2a98208b21ee2d820df2c526af75ace863/src/core/thread.d#L2230

[yebblies]

Can't we add a way to mark asm blocks as nothrow or something? Having them automatically ignored seems kind of dodgy.

[ibuclaw]

Can't we add a way to mark asm blocks as nothrow or something? Having them automatically ignored seems kind of dodgy.

The question isn't ignoring them. It's about whether or not saying that asm throws is a valid statement in the first place.

[ibuclaw]

The /real/ dodgyness is this: https://issues.dlang.org/show_bug.cgi?id=12979

[yebblies]

The question isn't ignoring them. It's about whether or not saying that asm throws is a valid statement in the first place.

If we can't verify it doesn't throw, how can we allow it in nothrow functions?

The /real/ dodgyness is this: https://issues.dlang.org/show_bug.cgi?id=12979

Yes.

[WalterBright]

Asm code can call other functions, which may throw.

[ibuclaw]

Asm code can call other functions, which may throw

I would have thought that you'd be able to work out if this could potentially happen, such as when you've taken the address of a function in an asm statement (asmSemantic ?) and the function is not marked as nothrow.

[WalterBright]

This kinda depends on how far you want the compiler go to analyze the asm instructions and figure out what it is doing. I find this to be fraught with hazards, as part of the point of clever asm code is to be clever.

Perhaps a better solution is to annotate the asm statement, as in:

asm nothrow { ... }

[WalterBright]

I'm going to close this as merely removing the error message doesn't fix the underlying issue - asm code can throw.

[MartinNowak]

I've posted a fix for Issue 12979 that implements asm nothrow {} (#4033).

https://github.com/D-Programming-Language/dmd/blob/master/src/func.c#L1778

BTW, please use permalinks when referencing line numbers. You can do so by pressing y on the file view (more).