Bug 21807 – Non-immutable data can be converted to immutable using function call in ctor

class Foo { this() { // char[12] pp; str = pp; // error str = bb(); // no error ??? } string str; } char[12] bb() { char[12] res; return res; } Also why it doesn't produce Error: escaping reference to stack allocated value returned by bb() ???

Or at least Deprecation: slice of static array temporary returned by X assigned to longer lived variable Y

If `bb` and the constructor are marked as @safe, DMD produces the following error: --- Error: reference to stack allocated value returned by bb() assigned to non-scope this.str --- Separately from this, compiling with `-preview=dip1000` causes DMD to produce the following error: --- Error: cannot implicitly convert expression bb() of type char[12] to string ---

Up to 2.062 : Failure with output: onlineapp.d(6): Error: cannot implicitly convert expression (bb()) of type char[12LU] to string Since 2.063 : Success and no output

Introduced by https://github.com/dlang/dmd/pull/1519

char[] a(const int[] arr) pure @safe; void b(const int[] arr) @safe { char[] c=a(arr); string d=a(arr); } For this code dip1000 rejects the conversion to string too. How is it related to dip1000?

(In reply to anonymous4 from comment #5) > char[] a(const int[] arr) pure @safe; > void b(const int[] arr) @safe > { > char[] c=a(arr); > string d=a(arr); > } > > For this code dip1000 rejects the conversion to string too. How is it > related to dip1000? It's not related to dip1000. Passing `-preview=dip1000` causes a different code path to be taken in the compiler, which ends up avoiding this bug by coincidence.

dlang/dmd pull request #12398 "Issue 21807 - Missing deprecation when slicing static array temporary..." was merged into stable: - 5110b4e6dc9849001b273bd443a2b67ac490dd1b by MoonlightSentinel: Issue 21807 - Missing deprecation when slicing static array temporary... ...in class methods. The checks for such slices relied on `va` while actually just caring about the current type. This was broken by [1] which clears `va` for class members to detect escapes of delegates. This also applied to the checks for struct temporaries/literals. [1] https://github.com/dlang/dmd/pull/8008 https://github.com/dlang/dmd/pull/12398

@MoonlightSentinel updated dlang/dmd pull request #12402 "Fix 21229 - Accept construction of union member as initialization" mentioning this issue: - Issue 21807 - Missing deprecation when slicing static array temporary... ...in class methods. The checks for such slices relied on `va` while actually just caring about the current type. This was broken by [1] which clears `va` for class members to detect escapes of delegates. This also applied to the checks for struct temporaries/literals. [1] https://github.com/dlang/dmd/pull/8008 https://github.com/dlang/dmd/pull/12402

@MoonlightSentinel created dlang/dmd pull request #12408 "Merge stable into master" mentioning this issue: - Issue 21807 - Missing deprecation when slicing static array temporary... ...in class methods. The checks for such slices relied on `va` while actually just caring about the current type. This was broken by [1] which clears `va` for class members to detect escapes of delegates. This also applied to the checks for struct temporaries/literals. [1] https://github.com/dlang/dmd/pull/8008 https://github.com/dlang/dmd/pull/12408

dlang/dmd pull request #12408 "Merge stable into master" was merged into master: - aea9ec8b1ce67f340a7a95564d3b2e8ae2de8d15 by MoonlightSentinel: Issue 21807 - Missing deprecation when slicing static array temporary... ...in class methods. The checks for such slices relied on `va` while actually just caring about the current type. This was broken by [1] which clears `va` for class members to detect escapes of delegates. This also applied to the checks for struct temporaries/literals. [1] https://github.com/dlang/dmd/pull/8008 https://github.com/dlang/dmd/pull/12408

@RazvanN7 created dlang/dmd pull request #13206 "Fix Issue 21807 - Issue 21807 - Non-immutable data can be converted to immutable using function call in ctor" fixing this issue: - Fix Issue 21807 - Issue 21807 - Non-immutable data can be converted to immutable using function call in ctor https://github.com/dlang/dmd/pull/13206

With current master, and @safe applied, the following deprecation is printed with or without -preview=dip1000: test.d(8): Deprecation: slice of static array temporary returned by `bb()` assigned to longer lived variable `this.str` This message is correct. Note that since the char[12] is a temporary value, there are no other references to it, so it can safely be converted to immutable. Closing as the compiler is working as expected.