Bug 9977 – Function local templates should be allowed

Currently DMD accepts declaring template aggregates and functions inside functions. void test1() { struct S1(T) { T value; } auto func1(T)(T value) { return value; } static assert(is(S1!int == struct)); assert(func1(10) == 10); } But raw template declaration is not allowed. void test2() { template S2(T) { struct S2 { T value; } } // line 10 template func2(T) { auto func2(T value) { return value; } } // line 11 static assert(is(S2!int == struct)); assert(func2(10) == 10); } Output: test.d(10): Error: template definitions aren't allowed inside functions test.d(11): Error: template definitions aren't allowed inside functions Today, I think this is not reasonable limitation.

(In reply to comment #0) > Today, I think this is not reasonable limitation. Yes, especially since this: auto func1(T)(T value) { return value; } really translates into this: template func1(T) { auto func1(T value) { return value; } } At least that's what I remember. Thanks for working on this.

Commits pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/707415dec87694c30a569dd1b67c496a9de7f648 fix Issue 9977 - Function local templates should be allowed https://github.com/D-Programming-Language/dmd/commit/006accc47fd0fb0a8299c258f66fdb0c505d9f16 Merge pull request #1919 from 9rnsr/fix9977 Issue 9977 - Function local templates should be allowed

In the changelog this should be underlined as a significant improvement of D. It's useful for unittests, to not pollute the module scope with template names that are used only inside the unittest.

(In reply to comment #4) > In the changelog this should be underlined as a significant improvement of D. > It's useful for unittests, to not pollute the module scope with template names > that are used only inside the unittest. Yes. I've added it to the pending pull request.