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Issue 3630 - bad error location in "has no effect in expression" error
Summary: bad error location in "has no effect in expression" error
Status: RESOLVED FIXED
Alias: None
Product: D
Classification: Unclassified
Component: dmd (show other issues)
Version: D2
Hardware: All All
: P2 major
Assignee: yebblies
URL:
Keywords: diagnostic, pull
: 6233 (view as issue list)
Depends on:
Blocks:
 
Reported: 2009-12-17 16:09 UTC by Vladimir Panteleev
Modified: 2015-06-09 05:11 UTC (History)
5 users (show)

See Also:


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Description Vladimir Panteleev 2009-12-17 16:09:57 UTC
Consider:

=== Module a.d ===
enum { A, B, C }

=== Module b.d ===
import a;

// ... thousands of lines of code ...
void foo()
{
    A;
}
// ... thousands of lines of code ...
==================

The error message outputted by the compiler will look like this:
a.d(1): Error: long has no effect in expression (0)

This is more serious considering that starting with 1.049, DMD forbids return expressions without side effects inside void functions. In my particular case, this was with the pretty-large DFL library, which required quite a bit of "divide-et-impera" to find the offending code.

By quickly looking at the compiler code, it looks like this happens because the expression statement is using the expression directly from the enumeration. The fix would involve instantiating an enum-reference expression each time an enumeration member is mentioned, or something like that.
Comment 1 yebblies 2011-06-12 23:19:46 UTC
*** Issue 3746 has been marked as a duplicate of this issue. ***
Comment 2 yebblies 2011-08-04 19:46:50 UTC
*** Issue 6233 has been marked as a duplicate of this issue. ***
Comment 4 github-bugzilla 2012-02-20 18:24:49 UTC
Commit pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/021f361bf01f91e76ccf2bc90483bce857149b54
Merge pull request #750 from yebblies/issue3630

Issue 3630 - bad error location in "has no effect in expression" error
Comment 5 github-bugzilla 2012-02-20 19:09:59 UTC
Commit pushed to dmd-1.x at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/f3ab2da302e894498bd4cfc71cacda844c4f8120
fix Issue 3630 - bad error location in has no effect in expression error
Comment 6 bearophile_hugs 2012-02-20 19:45:51 UTC
I am seeing this, I don't know why:


dmc -c -Iroot;\dm\include  -o  -cpp  func
            e = p->type->defaultInitLiteral();
                                            ^
func.c(2488) : Error: 1 actual arguments expected for function, had 0
--- errorlevel 1
Comment 7 yebblies 2012-02-20 19:55:47 UTC
(In reply to comment #6)
> I am seeing this, I don't know why:
> 
> 
> dmc -c -Iroot;\dm\include  -o  -cpp  func
>             e = p->type->defaultInitLiteral();
>                                             ^
> func.c(2488) : Error: 1 actual arguments expected for function, had 0
> --- errorlevel 1

Because Walter merged pull 41 which added that code.  I'm glad I took away the default parameter, we just avoided a new missing line number bug.