[Issue 14387] Disallow string literals as assert conditions

Apr 02, 2015

Don

Apr 05, 2015

Vladimir Panteleev

Dec 04, 2022

Dec 17, 2022

Nov 20, 2023

Nov 24, 2023

Dec 29, 2023

Jan 26, 2024

April 02, 2015

[Issue 14387] Disallow string literals as assert conditions

Posted by Don

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Don

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https://issues.dlang.org/show_bug.cgi?id=14387

--- Comment #1 from Don <clugdbug@yahoo.com.au> ---
The spec says:

"As a debugging tool, the compiler may insert checks to verify that the condition indeed holds by evaluating AssignExpression at runtime. If it evaluates to a non-null class reference, the class invariant is run. Otherwise, if it evaluates to a non-null pointer to a struct, the struct invariant is run. Otherwise, if the result is false, an AssertError is thrown. If the result is true, then no exception is thrown. In this way, if a bug in the code causes the assertion to fail, execution is aborted, prompting the programmer to fix the problem. "

This does not mention the case where the expression evaluates to a string literal.

At the very least this is a bug in the spec. It seems that, if the expression evaluates neither to a class reference, nor to a pointer to a struct, then the expression is implictly converted to bool. But the spec doesn't say that.

IMHO it's also pretty weird that string literals are implicitly convertable to bool. Note that they weren't convertable in D1:  assert("abc"); and if("abc") both generated compile-time errors. I don't think that was an intentional change, but I could be wrong.

--

https://issues.dlang.org/show_bug.cgi?id=14387 Vladimir Panteleev <thecybershadow@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |thecybershadow@gmail.com --- Comment #2 from Vladimir Panteleev <thecybershadow@gmail.com> --- (In reply to Don from comment #1) > IMHO it's also pretty weird that string literals are implicitly convertable to bool. Note that they weren't convertable in D1: assert("abc"); and if("abc") both generated compile-time errors. I don't think that was an intentional change, but I could be wrong. For non-static assert, D1 and D2 pre 2.023 say: test.d(4): Error: expression "test" of type invariant(char[4u]) does not have a boolean value >From 2.023 changelog: "the type of a string literal is now invariant(char)[] rather than invariant(char)[length_of_string]. It is still implicitly convertible to the latter. This is intended to reduce template instantiation bloat." This is a case of dynamic arrays implicitly converting to bool whether they're null or non-null. So, this will automatically be "fixed" when implicit array-to-bool conversion is deprecated ( https://github.com/D-Programming-Language/dmd/pull/2885 ). --

https://issues.dlang.org/show_bug.cgi?id=14387 Nick Treleaven <nick@geany.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |nick@geany.org --- Comment #3 from Nick Treleaven <nick@geany.org> --- > this will automatically be "fixed" when implicit array-to-bool conversion is deprecated ( https://github.com/D-Programming-Language/dmd/pull/2885 ). Sadly that was reverted and Issue 4733 was marked as WONTFIX. --

https://issues.dlang.org/show_bug.cgi?id=14387 Iain Buclaw <ibuclaw@gdcproject.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Priority|P1 |P4 --

https://issues.dlang.org/show_bug.cgi?id=14387 Dlang Bot <dlang-bot@dlang.rocks> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |pull --- Comment #4 from Dlang Bot <dlang-bot@dlang.rocks> --- @ntrel created dlang/dmd pull request #15837 "Deprecate boolean evaluation of array/string literals" fixing this issue: - Deprecate boolean evaluation of array/string literals Fix Issue 14387 - Disallow string literals as assert conditions. https://github.com/dlang/dmd/pull/15837 --

https://issues.dlang.org/show_bug.cgi?id=14387 --- Comment #5 from Dlang Bot <dlang-bot@dlang.rocks> --- @ntrel created dlang/dmd pull request #15860 "Deprecate string literals as (static) assert conditions" fixing this issue: - Deprecate string literals as assert conditions Fix Issue 14387 - Disallow string literals as assert conditions https://github.com/dlang/dmd/pull/15860 --

https://issues.dlang.org/show_bug.cgi?id=14387 Dlang Bot <dlang-bot@dlang.rocks> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution|--- |FIXED --- Comment #6 from Dlang Bot <dlang-bot@dlang.rocks> --- dlang/dmd pull request #15860 "Deprecate string literals as (static) assert conditions" was merged into master: - 55d0483a5d5ceef59327cde7cb12124d98547459 by Nick Treleaven: Deprecate string literals as assert conditions Fix Issue 14387 - Disallow string literals as assert conditions https://github.com/dlang/dmd/pull/15860 --

https://issues.dlang.org/show_bug.cgi?id=14387 Nick Treleaven <nick@geany.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |temtaime@gmail.com --- Comment #7 from Nick Treleaven <nick@geany.org> --- *** Issue 11080 has been marked as a duplicate of this issue. *** --

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