Reland Reland [clang][modules-driver] Add scanner to detect C++20 module presence (#147630) #153497
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…ule presence (llvm#147630) 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 the reland (2d31fc8) for commit ded1426. The previous reland failed because the link dependency on clangLex was missing. Following the RFC linked below, the issue has now been addressed by properly linking against clangLex. https://discourse.llvm.org/t/rfc-driver-link-the-driver-against-clangdependencyscanning-clangast-clangfrontend-clangserialization-and-clanglex
llvmbot
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@llvm/pr-subscribers-clang-driver @llvm/pr-subscribers-clang Author: Naveen Seth Hanig (naveen-seth) ChangesThis patch is part of a series to support driver managed module builds for C++ named modules and Clang modules. For now, it is enabled only with the 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 RFC for driver managed module builds: 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: Patch is 20.41 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/153497.diff 9 Files Affected:
diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index 0f17f4aa761ea..6df8f9932f30f 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -581,6 +581,13 @@ def err_drv_reduced_module_output_overrided : Warning<
"please consider use '-fmodule-output=' to specify the output file for reduced BMI explicitly">,
InGroup<DiagGroup<"reduced-bmi-output-overrided">>;
+def remark_found_cxx20_module_usage : Remark<
+ "found C++20 module usage in file '%0'">,
+ InGroup<ModulesDriver>;
+def remark_performing_driver_managed_module_build : Remark<
+ "performing driver managed module build">,
+ InGroup<ModulesDriver>;
+
def warn_drv_delayed_template_parsing_after_cxx20 : Warning<
"-fdelayed-template-parsing is deprecated after C++20">,
InGroup<DiagGroup<"delayed-template-parsing-in-cxx20">>;
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index ccb18aa37447e..78726ecc869db 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -628,6 +628,7 @@ def ModuleConflict : DiagGroup<"module-conflict">;
def ModuleFileExtension : DiagGroup<"module-file-extension">;
def ModuleIncludeDirectiveTranslation : DiagGroup<"module-include-translation">;
def ModuleMap : DiagGroup<"module-map">;
+def ModulesDriver : DiagGroup<"modules-driver">;
def RoundTripCC1Args : DiagGroup<"round-trip-cc1-args">;
def NewlineEOF : DiagGroup<"newline-eof">;
def Nullability : DiagGroup<"nullability">;
diff --git a/clang/include/clang/Driver/Driver.h b/clang/include/clang/Driver/Driver.h
index 4d32552b7f85f..b9b187ada8add 100644
--- a/clang/include/clang/Driver/Driver.h
+++ b/clang/include/clang/Driver/Driver.h
@@ -512,6 +512,9 @@ class Driver {
/// BuildActions - Construct the list of actions to perform for the
/// given arguments, which are only done for a single architecture.
+ /// If the compilation is an explicit module build, delegates to
+ /// BuildDriverManagedModuleBuildActions. Otherwise, BuildDefaultActions is
+ /// used.
///
/// \param C - The compilation that is being built.
/// \param Args - The input arguments.
@@ -796,6 +799,35 @@ class Driver {
/// compilation based on which -f(no-)?lto(=.*)? option occurs last.
void setLTOMode(const llvm::opt::ArgList &Args);
+ /// BuildDefaultActions - Constructs the list of actions to perform
+ /// for the provided arguments, which are only done for a single architecture.
+ ///
+ /// \param C - The compilation that is being built.
+ /// \param Args - The input arguments.
+ /// \param Actions - The list to store the resulting actions onto.
+ void BuildDefaultActions(Compilation &C, llvm::opt::DerivedArgList &Args,
+ const InputList &Inputs, ActionList &Actions) const;
+
+ /// BuildDriverManagedModuleBuildActions - Performs a dependency
+ /// scan and constructs the list of actions to perform for dependency order
+ /// and the provided arguments. This is only done for a single a architecture.
+ ///
+ /// \param C - The compilation that is being built.
+ /// \param Args - The input arguments.
+ /// \param Actions - The list to store the resulting actions onto.
+ void BuildDriverManagedModuleBuildActions(Compilation &C,
+ llvm::opt::DerivedArgList &Args,
+ const InputList &Inputs,
+ ActionList &Actions) const;
+
+ /// Scans the leading lines of the C++ source inputs to detect C++20 module
+ /// usage.
+ ///
+ /// \returns True if module usage is detected, false otherwise, or an error on
+ /// read failure.
+ llvm::ErrorOr<bool>
+ ScanInputsForCXX20ModulesUsage(const InputList &Inputs) const;
+
/// Retrieves a ToolChain for a particular \p Target triple.
///
/// Will cache ToolChains for the life of the driver object, and create them
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index ee4df6727e7f0..0e9e0971680e2 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3296,6 +3296,13 @@ defm modules_reduced_bmi : BoolOption<"f", "modules-reduced-bmi",
PosFlag<SetTrue, [], [ClangOption, CC1Option],
"Generate the reduced BMI">>;
+def fmodules_driver : Flag<["-"], "fmodules-driver">,
+ Group<f_Group>, Visibility<[ClangOption]>,
+ HelpText<"Enable support for driver managed module builds (experimental)">;
+def fno_modules_driver : Flag<["-"], "fno-modules-driver">,
+ Group<f_Group>, Visibility<[ClangOption]>,
+ HelpText<"Disable support for driver managed module builds (experimental)">;
+
def experimental_modules_reduced_bmi : Flag<["-"], "fexperimental-modules-reduced-bmi">,
Group<f_Group>, Visibility<[ClangOption, CC1Option]>, Alias<fmodules_reduced_bmi>;
diff --git a/clang/include/clang/Lex/DependencyDirectivesScanner.h b/clang/include/clang/Lex/DependencyDirectivesScanner.h
index f9fec3998ca53..c0b742d652a03 100644
--- a/clang/include/clang/Lex/DependencyDirectivesScanner.h
+++ b/clang/include/clang/Lex/DependencyDirectivesScanner.h
@@ -135,6 +135,13 @@ void printDependencyDirectivesAsSource(
ArrayRef<dependency_directives_scan::Directive> Directives,
llvm::raw_ostream &OS);
+/// Scan an input source buffer for C++20 named module usage.
+///
+/// \param Source The input source buffer.
+///
+/// \returns true if any C++20 named modules related directive was found.
+bool scanInputForCXX20ModulesUsage(StringRef Source);
+
/// Functor that returns the dependency directives for a given file.
class DependencyDirectivesGetter {
public:
diff --git a/clang/lib/Driver/CMakeLists.txt b/clang/lib/Driver/CMakeLists.txt
index 45782cbd9d16d..7c4f70b966c48 100644
--- a/clang/lib/Driver/CMakeLists.txt
+++ b/clang/lib/Driver/CMakeLists.txt
@@ -98,5 +98,6 @@ add_clang_library(clangDriver
LINK_LIBS
clangBasic
+ clangLex
${system_libs}
)
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 8c0bba938a09b..d682ffc832c83 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -66,6 +66,7 @@
#include "clang/Driver/Tool.h"
#include "clang/Driver/ToolChain.h"
#include "clang/Driver/Types.h"
+#include "clang/Lex/DependencyDirectivesScanner.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallSet.h"
@@ -4188,6 +4189,11 @@ void Driver::handleArguments(Compilation &C, DerivedArgList &Args,
YcArg = nullptr;
}
+ if (Args.hasArgNoClaim(options::OPT_fmodules_driver))
+ // TODO: Check against all incompatible -fmodules-driver arguments
+ if (!ModulesModeCXX20 && !Args.hasArgNoClaim(options::OPT_fmodules))
+ Args.eraseArg(options::OPT_fmodules_driver);
+
Arg *FinalPhaseArg;
phases::ID FinalPhase = getFinalPhase(Args, &FinalPhaseArg);
@@ -4314,6 +4320,33 @@ void Driver::handleArguments(Compilation &C, DerivedArgList &Args,
}
}
+static bool hasCXXModuleInputType(const Driver::InputList &Inputs) {
+ const auto IsTypeCXXModule = [](const auto &Input) -> bool {
+ const auto TypeID = Input.first;
+ return (TypeID == types::TY_CXXModule);
+ };
+ return llvm::any_of(Inputs, IsTypeCXXModule);
+}
+
+llvm::ErrorOr<bool>
+Driver::ScanInputsForCXX20ModulesUsage(const InputList &Inputs) const {
+ const auto CXXInputs = llvm::make_filter_range(
+ Inputs, [](const auto &Input) { return types::isCXX(Input.first); });
+ for (const auto &Input : CXXInputs) {
+ StringRef Filename = Input.second->getSpelling();
+ auto ErrOrBuffer = VFS->getBufferForFile(Filename);
+ if (!ErrOrBuffer)
+ return ErrOrBuffer.getError();
+ const auto Buffer = std::move(*ErrOrBuffer);
+
+ if (scanInputForCXX20ModulesUsage(Buffer->getBuffer())) {
+ Diags.Report(diag::remark_found_cxx20_module_usage) << Filename;
+ return true;
+ }
+ }
+ return false;
+}
+
void Driver::BuildActions(Compilation &C, DerivedArgList &Args,
const InputList &Inputs, ActionList &Actions) const {
llvm::PrettyStackTraceString CrashInfo("Building compilation actions");
@@ -4325,6 +4358,33 @@ void Driver::BuildActions(Compilation &C, DerivedArgList &Args,
handleArguments(C, Args, Inputs, Actions);
+ if (Args.hasFlag(options::OPT_fmodules_driver,
+ options::OPT_fno_modules_driver, false)) {
+ // TODO: Move the logic for implicitly enabling explicit-module-builds out
+ // of -fmodules-driver once it is no longer experimental.
+ // Currently, this serves diagnostic purposes only.
+ bool UsesCXXModules = hasCXXModuleInputType(Inputs);
+ if (!UsesCXXModules) {
+ const auto ErrOrScanResult = ScanInputsForCXX20ModulesUsage(Inputs);
+ if (!ErrOrScanResult) {
+ Diags.Report(diag::err_cannot_open_file)
+ << ErrOrScanResult.getError().message();
+ return;
+ }
+ UsesCXXModules = *ErrOrScanResult;
+ }
+ if (UsesCXXModules || Args.hasArg(options::OPT_fmodules))
+ BuildDriverManagedModuleBuildActions(C, Args, Inputs, Actions);
+ return;
+ }
+
+ BuildDefaultActions(C, Args, Inputs, Actions);
+}
+
+void Driver::BuildDefaultActions(Compilation &C, DerivedArgList &Args,
+ const InputList &Inputs,
+ ActionList &Actions) const {
+
bool UseNewOffloadingDriver =
C.isOffloadingHostKind(Action::OFK_OpenMP) ||
C.isOffloadingHostKind(Action::OFK_SYCL) ||
@@ -4608,6 +4668,13 @@ void Driver::BuildActions(Compilation &C, DerivedArgList &Args,
Args.ClaimAllArgs(options::OPT_cl_ignored_Group);
}
+void Driver::BuildDriverManagedModuleBuildActions(
+ Compilation &C, llvm::opt::DerivedArgList &Args, const InputList &Inputs,
+ ActionList &Actions) const {
+ Diags.Report(diag::remark_performing_driver_managed_module_build);
+ return;
+}
+
/// Returns the canonical name for the offloading architecture when using a HIP
/// or CUDA architecture.
static StringRef getCanonicalArchString(Compilation &C,
diff --git a/clang/lib/Lex/DependencyDirectivesScanner.cpp b/clang/lib/Lex/DependencyDirectivesScanner.cpp
index 9ccff5e3342d5..eee57c786442a 100644
--- a/clang/lib/Lex/DependencyDirectivesScanner.cpp
+++ b/clang/lib/Lex/DependencyDirectivesScanner.cpp
@@ -83,6 +83,8 @@ struct Scanner {
/// \returns True on error.
bool scan(SmallVectorImpl<Directive> &Directives);
+ friend bool clang::scanInputForCXX20ModulesUsage(StringRef Source);
+
private:
/// Lexes next token and advances \p First and the \p Lexer.
[[nodiscard]] dependency_directives_scan::Token &
@@ -1075,3 +1077,51 @@ void clang::printDependencyDirectivesAsSource(
}
}
}
+
+static void skipUntilMaybeCXX20ModuleDirective(const char *&First,
+ const char *const End) {
+ assert(First <= End);
+ while (First != End) {
+ if (*First == '#') {
+ ++First;
+ skipToNewlineRaw(First, End);
+ }
+ skipWhitespace(First, End);
+ if (const auto Len = isEOL(First, End)) {
+ First += Len;
+ continue;
+ }
+ break;
+ }
+}
+
+bool clang::scanInputForCXX20ModulesUsage(StringRef Source) {
+ const char *First = Source.begin();
+ const char *const End = Source.end();
+ skipUntilMaybeCXX20ModuleDirective(First, End);
+ if (First == End)
+ return false;
+
+ // Check if the next token can even be a module directive before creating a
+ // full lexer.
+ if (!(*First == 'i' || *First == 'e' || *First == 'm'))
+ return false;
+
+ llvm::SmallVector<dependency_directives_scan::Token> Tokens;
+ Scanner S(StringRef(First, End - First), Tokens, nullptr, SourceLocation());
+ S.TheLexer.setParsingPreprocessorDirective(true);
+ if (S.lexModule(First, End))
+ return false;
+ auto IsCXXNamedModuleDirective = [](const DirectiveWithTokens &D) {
+ switch (D.Kind) {
+ case dependency_directives_scan::cxx_module_decl:
+ case dependency_directives_scan::cxx_import_decl:
+ case dependency_directives_scan::cxx_export_module_decl:
+ case dependency_directives_scan::cxx_export_import_decl:
+ return true;
+ default:
+ return false;
+ }
+ };
+ return llvm::any_of(S.DirsWithToks, IsCXXNamedModuleDirective);
+}
diff --git a/clang/test/Driver/modules-driver-cxx20-module-usage-scanner.cpp b/clang/test/Driver/modules-driver-cxx20-module-usage-scanner.cpp
new file mode 100644
index 0000000000000..a434587a78759
--- /dev/null
+++ b/clang/test/Driver/modules-driver-cxx20-module-usage-scanner.cpp
@@ -0,0 +1,192 @@
+// The driver never checks to implicitly enable the explicit module build
+// support unless at least two input files are provided.
+// To trigger the C++20 module usage check, we always pass a second dummy file
+// as input.
+// TODO: Remove -fmodules everywhere once implicitly enabled explicit module
+// builds are supported.
+
+// RUN: split-file %s %t
+//--- empty.cpp
+// Nothing here
+
+//--- only-global.cpp
+// RUN: %clang -std=c++20 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/only-global.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK1
+// CHECK1: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+module;
+
+//--- only-import.cpp
+// RUN: %clang -std=c++20 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/only-import.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK2
+// CHECK2: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+import A;
+
+//--- only-export.cpp
+// RUN: %clang -std=c++20 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/only-export.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK3
+// CHECK3: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+export module A;
+
+//--- leading-line-comment.cpp
+// RUN: %clang -std=c++20 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/leading-line-comment.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK4
+// CHECK4: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+// My line comment
+import A;
+
+//--- leading-block-comment1.cpp
+// RUN: %clang -std=c++20 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/leading-block-comment1.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK5
+// CHECK5: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+/*My block comment */
+import A;
+
+//--- leading-block-comment2.cpp
+// RUN: %clang -std=c++20 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/leading-block-comment2.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK6
+// CHECK6: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+/*My line comment */ import A;
+
+//--- inline-block-comment1.cpp
+// RUN: %clang -std=c++20 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/leading-block-comment1.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK7
+// CHECK7: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+export/*a comment*/module/*another comment*/A;
+
+//--- inline-block-comment2.cpp
+// RUN: %clang -std=c++20 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/leading-block-comment2.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK8
+// CHECK8: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+module/*a comment*/;
+
+//--- leading-directives.cpp
+// RUN: %clang -std=c++23 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/leading-directives.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK9
+// CHECK9: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+#define A
+#undef A
+#if A
+#ifdef A
+#elifdef A
+#elifndef A
+#endif
+#ifndef A
+#elif A
+#else
+#endif
+#endif
+#pragma once;
+#include <iostream>
+import m;
+
+//--- multiline-directive.cpp
+// RUN: %clang -std=c++23 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/multiline-directive.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK10
+// CHECK10: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+#define MACRO(a, \
+ b) \
+ call((a), \
+ (b)
+import a;
+
+//--- leading-line-splice.cpp
+// RUN: %clang -std=c++23 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/leading-line-splice.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK11
+// CHECK11: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+\
+module;
+
+//--- leading-line-splice-trailing-whitespace.cpp
+// RUN: %clang -std=c++23 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/leading-line-splice-trailing-whitespace.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK12
+// CHECK12: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+// v This backslash has trailing whitespace.
+ \
+export module A;
+
+//--- comment-line-splice.cpp
+// RUN: %clang -std=c++23 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/comment-line-splice.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --allow-empty --check-prefix=CHECK13
+// CHECK13-NOT: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+// My comment continues next-line!\
+import A;
+
+//--- comment-line-splice-trailing-whitespace.cpp
+// RUN: %clang -std=c++23 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/comment-line-splice-trailing-whitespace.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --allow-empty --check-prefix=CHECK14
+// CHECK14-NOT: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+// My comment continues next-line! This backslash has trailing whitespace. -> \
+module;
+
+//--- line-splice-in-directive1.cpp
+// RUN: %clang -std=c++23 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/line-splice-in-directive1.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK15
+// CHECK15: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+
+module\
+;
+
+//--- line-splice-in-directive2.cpp
+// RUN: %clang -std=c++23 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/line-splice-in-directive2.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK16
+// CHECK16: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+
+export\
+ module\
+ A;
+
+//--- no-module-usage1.cpp
+// RUN: %clang -std=c++23 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/no-module-usage1.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --allow-empty --check-prefix=CHECK17
+// CHECK17-NOT: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+auto main() -> int {}
+
+//--- no-module-usage2.cpp
+// RUN: %clang -std=c++23 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/no-module-usage2.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --allow-empty --check-prefix=CHECK18
+// CHECK18-NOT: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+moduleStruct{};
+
+//--- no-module-usage3.cpp
+// RUN: %clang -std=c++23 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/no-module-usage3.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --allow-empty --check-prefix=CHECK19
+// CHECK19-NOT: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+export_struct{};
+
+//--- no-module-usage-namespace-import.cpp
+// RUN: %clang -std=c++23 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/no-module-usage-namespace-import.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --allow-empty --check-prefix=CHECK20
+// CHECK20-NOT: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+import::inner xi = {};
+
+//--- no-module-usage-namespace-module.cpp
+// RUN: %clang -std=c++23 -ccc-print-phases -fmodules-driver -Rmodules-driver \
+// RUN: %t/no-module-usage-namespace-module.cpp %t/empty.cpp 2>&1 \
+// RUN: | FileCheck %s --allow-empty --check-pre...
[truncated]
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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-driverflag 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 stdusage in a single-file compilation, which would then activate the modules driver. For performance measurements on this, seehttps://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