D needs to be honest

[Jonathan Marler]

I filed this issue 
(https://issues.dlang.org/show_bug.cgi?id=18517) about 8 months 
ago.  It provides a couple test cases that show that import order 
changes the semantics of D programs and the order in which 
modules are passed to the compiler also changes semantics.  This 
behavior has existed long enough that it's probably time for D to 
remove and/or qualify some of its claims.  Statements like:

https://dlang.org/spec/module.html

> The order in which ImportDeclarations occur has no significance.

> The order in which modules are imported does not affect the 
> semantics.

The bugzilla issue above shows cases where these statements are 
demonstrated to be false, and I wouldn't characterize the issue 
as a bug, rather, a fundamental problem with the way D handles 
module imports.  The language definition as it exists does not 
allow import order to be invariant.  Note there are a number of 
ways to fix this issue (see PRs below) but note that they do 
require changes to the way D handles imports.

> The semantics of a module are not affected by what imports it.

The module name and or the namespace it exists in will change 
depending on how the module is imported.  It can change depending 
on if it was passed in on the command line, or loaded from an 
import by another module, and the path from which it was loaded 
can change depending on which module loaded it first.

Based on the response of my pull requests to fix these issues, 
its clear that these issues are low on the priority list. This is 
fine and maybe it's better that the maintainers focus on other 
things rather than this problem, however, I think it's been long 
enough that keeping these claims on the website and in the 
documentation is bordering on being deceptive and unethical.  
Everyone will have an opinion on where you draw the line, but in 
my opinion, it's time to come clean.

I've included my pull requests related to these issues.  Feel 
free to look into them if you want more information.

Relevant Pull Requests:

Fix module/import order invariance: 
https://github.com/dlang/dmd/pull/7900
Interpret imports the same regardless of other modules passed on 
the command line: https://github.com/dlang/dmd/pull/7878
Add broken import order invariance tests: 
https://github.com/dlang/dmd/pull/8165
Deprecate import/module name mismatch (ALL CASES): 
https://github.com/dlang/dmd/pull/7778