std-tool below may be a wrapper as Gabi suggested or the compiler itself.
For me it seems that a wrapper ot the compiler itself is implementation
defined, but a paper is required.


Ran.

On Mon, Dec 4, 2023, 19:43 Ran Regev <regev.ran_at_[hidden]> wrote:

>
>
> On Mon, Dec 4, 2023, 19:31 Tom Honermann via SG15 <sg15_at_[hidden]>
> wrote:
>
>> If this can be done without too much difficulty, great.
>>
>> However, would you expect this to work for both -stdlib=libc++ and
>> -stdlib=libstdc++? How about when Clang is used with Microsoft's
>> standard library (for which there is no corresponding -stdlib option)?
>>
>
> I think defaults should be used when no value is supplied. Like, -O0 is
> the default in all compilers unless otherwise specified.
>
> The same for default std lib and any other parameter.
>
> The target is to enable portable:
> # std-tool -o hello hello.cpp
>
> Even when hello.cpp has import std; directive inside it.
>
>
> Ran.
>
>> Tom.
>> On 12/4/23 1:00 AM, Chuanqi Xu via SG15 wrote:
>>
>> Hi Guys,
>>
>> This post is mainly about some random thoughts about teachability of
>> std modules. Also [P2412R0: Minimal module support for the standard
>> library] (
>> https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2412r0.pdf)
>> mentions that the std module is important for educations and beginners. If
>> there are more interests, I can try to summarize them into a paper.
>>
>> When I start to learn C++, I only need to copy a hello world example
>> and run:
>> ```
>> clang++ hello.cpp -o hello
>> ```
>>
>> However, with the current direction of std modules, the beginner need
>> to install the build systems and try to copy the build scripts that them
>> can hardly understand. Possibly some simpler form of
>> https://libcxx.llvm.org/Modules.html. But it still seems scaring to
>> beginners.
>>
>> And I am wondering if we can simplify the process. For example, the
>> beginners can compile a hello world example with std module:
>> ```
>> import std;
>> int main() { std::cout << "Hello modular world\n"; }
>> ```
>> with a single command line:
>> ```
>> clang++ -std=c++23 hello.cpp -o hello
>> ```
>>
>> The compiler may achieve that when:
>> - the std module is required but not provided.
>> - the path to std module's BMI is not specified. (implied that the
>> invocation doesn't from build systems)
>> - the final output is an executable.
>> - the std module's source exists in the installed path (being discussed
>> in https://github.com/llvm/llvm-project/issues/73089).
>>
>> then the compiler can try to compile the std module's source to BMI and
>> object file. Then we can import the BMI and link the object file. There are
>> some details. e.g., where should we put the BMI? Should we try to reuse the
>> BMIs? Can we extend the process to other modules? They are open questions
>> and my answers are:
>> - By default, they should be in `/tmp` and if `-save-temps` is specified,
>> they'll be in the same directory with the temporaries.
>> - The compiler shouldn't try to reuse the BMIs. That is the job of the
>> build systems.
>> - No, we can't. It is possible for std module since we'll try to
>> standardize the locations of std modules sources. So that the tools are
>> able to find the source of std modules. But it is not the case for other
>> generalized modules. Also I think this is the job of build systems too.
>>
>> The motivation is primarily for beginners and educations. How do you
>> feel about the idea?
>>
>> Thanks,
>> Chuanqi
>>
>>
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>