This patch is part of a series to support driver managed module builds
for C++ named modules and Clang modules.
This introduces a scanner that detects C++ named module usage early in
the driver with only negligible overhead.
For now, it is enabled only with the `-fmodules-driver` flag and serves
solely diagnostic purposes. In the future, the scanner will be enabled
for any (modules-driver compatible) compilation with two or more inputs,
and will help the driver determine whether to implicitly enable the
modules driver.
Since the scanner adds very little overhead, we are also exploring
enabling it for compilations with only a single input. This approach
could allow us to detect `import std` usage in a single-file
compilation, which would then activate the modules driver. For
performance measurements on this, see
https://github.com/naveen-seth/llvm-dev-cxx-modules-check-benchmark.
RFC for driver managed module builds:
https://discourse.llvm.org/t/rfc-modules-support-simple-c-20-modules-use-from-the-clang-driver-without-a-build-system
This patch relands the reland (2d31fc8) for commit ded1426. The earlier
reland failed due to a missing link dependency on `clangLex`. This
reland fixes the issue by adding the link dependency after discussing it
in the following RFC:
https://discourse.llvm.org/t/rfc-driver-link-the-driver-against-clangdependencyscanning-clangast-clangfrontend-clangserialization-and-clanglex
This patch is part of a series to natively support C++20 module usage
from the Clang driver (without requiring an external build system). This
introduces a new scanner that detects C++20 module usage in source files
without using the preprocessor or lexer.
For now, it is enabled only with the `-fmodules-driver` flag and serves
solely diagnostic purposes. In the future, the scanner will be enabled
for any (modules-driver compatible) compilation with two or more inputs,
and will help the driver determine whether to implicitly enable the
modules driver.
Since the scanner adds very little overhead, we are also exploring
enabling it for compilations with only a single input. This approach
could allow us to detect `import std` usage in a single-file
compilation, which would then activate the modules driver. For
performance measurements on this, see
https://github.com/naveen-seth/llvm-dev-cxx-modules-check-benchmark.
RFC:
https://discourse.llvm.org/t/rfc-modules-support-simple-c-20-modules-use-from-the-clang-driver-without-a-build-system
This patch relands commit ded1426. The CI failure is resolved by
removing the compatibility warning for using the `-fmodules-driver` flag
with pre-C++20 standards, which also better aligns its behavior with
other features/flags supported only in newer standards.
Reverts llvm/llvm-project#145220
This breaks CI when building the documentation
```
Included from /home/runner/work/llvm-project/llvm-project/clang/docs/../include/clang/Basic/Diagnostic.td:74:
/home/runner/work/llvm-project/llvm-project/clang/docs/../include/clang/Basic/DiagnosticGroups.td:628:5: error: Diagnostic group contains both remark and non-remark diagnostics
def ModulesDriver : DiagGroup<"modules-driver">;
^
```
https://github.com/llvm/llvm-project/actions/runs/16116118496/job/45470268367
This PR is part of a series to natively support C++20 module usage from
the Clang driver (without requiring an external build system).
This introduces a new scanner that detects C++20 module usage in source
files without using the preprocessor or lexer.
For now, it is enabled only with the `-fmodules-driver` flag and serves
solely diagnostic purposes. In the future, the scanner will be enabled
for any (modules-driver compatible) compilation with two or more inputs,
and will help the driver determine whether to implicitly enable the
modules driver.
Since the scanner adds very little overhead, we are also exploring
enabling it for compilations with only a single input. This approach
could allow us to detect `import std` usage in a single-file
compilation, which would then activate the modules driver.
For performance measurements on this, see
https://github.com/naveen-seth/llvm-dev-cxx-modules-check-benchmark.
RFC:
https://discourse.llvm.org/t/rfc-modules-support-simple-c-20-modules-use-from-the-clang-driver-without-a-build-system
