[clang][modules-driver] Add scanner to detect C++20 module presence #145220
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@llvm/pr-subscribers-clang-modules @llvm/pr-subscribers-clang Author: Naveen Seth Hanig (naveen-seth) ChangesThis PR is part of a series aimed at implementing native support for explicit module builds from the Clang driver. For now, it is enabled only with the -fmodules-driver flag and serves solely diagnostic purposes. In the future, the scanner will help the driver determine whether to implicitly perform an explicit module build and will be enabled for any (modules-driver compatible) compilation with 2 or more inputs. 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 Patch is 20.73 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/145220.diff 6 Files Affected:
diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index 29f6480ba935c..9ed50b6807d2a 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -577,6 +577,19 @@ 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_fmodules_driver_enabled : Remark<
+ "support for explicit module builds enabled (experimental)">,
+ InGroup<ModulesDriver>;
+def remark_found_cxx20_module_usage : Remark<
+ "found C++20 module usage in file '%0'">,
+ InGroup<ModulesDriver>;
+def remark_performing_explicit_module_build : Remark<
+ "performing explicit module build">,
+ InGroup<ModulesDriver>;
+def warn_modules_driver_unsupported_standard : Warning<
+ "'-fmodules-driver' is not supported before C++20">,
+ 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 beda73e675fc6..1baede2d0c324 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -625,6 +625,7 @@ 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 7ca848f11b561..9f9518942270a 100644
--- a/clang/include/clang/Driver/Driver.h
+++ b/clang/include/clang/Driver/Driver.h
@@ -505,6 +505,8 @@ 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
+ /// BuildExplicitModuleBuildActions. Otherwise, uses BuildDefaultActions.
///
/// \param C - The compilation that is being built.
/// \param Args - The input arguments.
@@ -790,6 +792,35 @@ 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;
+
+ /// BuildExplicitModuleBuildActions - 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 BuildExplicitModuleBuildActions(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>
+ ScanInputsForCXXModuleUsage(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 152df89118a6a..48d7d520bbfab 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3240,6 +3240,13 @@ def modules_reduced_bmi : Flag<["-"], "fmodules-reduced-bmi">,
HelpText<"Generate the reduced BMI">,
MarshallingInfoFlag<FrontendOpts<"GenReducedBMI">>;
+def fmodules_driver : Flag<["-"], "fmodules-driver">,
+ Group<f_Group>, Visibility<[ClangOption]>,
+ HelpText<"Enable support for explicit module builds from the driver (experimental)">;
+def fno_modules_driver : Flag<["-"], "fno-modules-driver">,
+ Group<f_Group>, Visibility<[ClangOption]>,
+ HelpText<"Disable support for explicit module builds from the driver (experimental)">;
+
def experimental_modules_reduced_bmi : Flag<["-"], "fexperimental-modules-reduced-bmi">,
Group<f_Group>, Visibility<[ClangOption, CC1Option]>, Alias<modules_reduced_bmi>;
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index eb60d907d2218..382db8a8ebd80 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -53,6 +53,7 @@
#include "ToolChains/WebAssembly.h"
#include "ToolChains/XCore.h"
#include "ToolChains/ZOS.h"
+#include "clang/Basic/CharInfo.h"
#include "clang/Basic/DiagnosticDriver.h"
#include "clang/Basic/TargetID.h"
#include "clang/Basic/Version.h"
@@ -4285,6 +4286,13 @@ 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) {
+ Diag(diag::warn_modules_driver_unsupported_standard);
+ Args.eraseArg(options::OPT_fmodules_driver);
+ }
+
Arg *FinalPhaseArg;
phases::ID FinalPhase = getFinalPhase(Args, &FinalPhaseArg);
@@ -4403,6 +4411,177 @@ void Driver::handleArguments(Compilation &C, DerivedArgList &Args,
}
}
+namespace {
+static void skipWhitespace(const char *&Ptr) {
+ while (isWhitespace(*Ptr))
+ ++Ptr;
+}
+
+// Returns the length of EOL, either 0 (no end-of-line), 1 (\n) or 2 (\r\n).
+static unsigned isEOL(const char *Ptr) {
+ if (*Ptr == '\0')
+ return 0;
+ if (*(Ptr + 1) != '\0' && isVerticalWhitespace(Ptr[0]) &&
+ isVerticalWhitespace(Ptr[1]) && Ptr[0] != Ptr[1])
+ return 2;
+ return !!isVerticalWhitespace(Ptr[0]);
+}
+
+static void skipLine(const char *&Ptr) {
+ for (;;) {
+ char LastNonWhitespace = ' ';
+ while (!isVerticalWhitespace(*Ptr) && *Ptr != '\0') {
+ if (!isHorizontalWhitespace(*Ptr))
+ LastNonWhitespace = *Ptr;
+ ++Ptr;
+ }
+
+ const unsigned Len = isEOL(Ptr);
+ if (!Len)
+ return;
+
+ Ptr += Len;
+ if (LastNonWhitespace != '\\')
+ break;
+ }
+}
+
+// Returns the length of a line splice sequence (including trailing
+// whitespace), or 0 if no line splice is found.
+static unsigned isLineSplice(const char *Start) {
+ if (*Start != '\\')
+ return 0;
+
+ const char *Ptr = Start + 1;
+ while (isHorizontalWhitespace(*Ptr))
+ ++Ptr;
+
+ if (unsigned Len = isEOL(Ptr))
+ return Ptr - Start + Len;
+ return 0;
+}
+
+static bool trySkipLineSplice(const char *&Ptr) {
+ if (unsigned Len = isLineSplice(Ptr); Len) {
+ Ptr += Len;
+ return true;
+ }
+ return false;
+}
+
+static bool trySkipDirective(const char *&Ptr) {
+ if (*Ptr != '#')
+ return false;
+
+ ++Ptr;
+ skipLine(Ptr);
+ return true;
+}
+
+static bool trySkipLineComment(const char *&Ptr) {
+ if (Ptr[0] != '/' || Ptr[1] != '/')
+ return false;
+
+ Ptr += 2;
+ skipLine(Ptr);
+ return true;
+}
+
+static bool trySkipBlockComment(const char *&Ptr) {
+ if (Ptr[0] != '/' || Ptr[1] != '*')
+ return false;
+
+ Ptr += 2;
+ while (*Ptr != '\0') {
+ if (Ptr[0] == '*' && Ptr[1] == '/') {
+ Ptr += 2; // '*/'
+ return true;
+ }
+ ++Ptr;
+ }
+ return true;
+}
+
+static bool trySkipComment(const char *&Ptr) {
+ return trySkipLineComment(Ptr) || trySkipBlockComment(Ptr);
+}
+
+// Skipps over comments and (non-module) directives
+static void skipToRelevantCXXModuleText(const char *&Ptr) {
+ while (*Ptr != '\0') {
+ skipWhitespace(Ptr);
+ if (trySkipComment(Ptr) || trySkipDirective(Ptr) || trySkipLineSplice(Ptr))
+ continue;
+ break; // Found relevant text!
+ }
+}
+
+static bool scanBufferForCXXModuleUsage(const llvm::MemoryBuffer &Buffer) {
+ const char *Ptr = Buffer.getBufferStart();
+ skipToRelevantCXXModuleText(Ptr);
+
+ // Check if buffer has enough bytes left to check for the module-related
+ // declaration fragment we want to check without making potentially
+ // memory-mapped buffer load unnecessary pages.
+ constexpr int MinKeywordLength = 6;
+ const char *Begin = Ptr;
+ for (int i = 0; i < MinKeywordLength; ++i) {
+ if (*Ptr == '\0')
+ return false;
+ ++Ptr;
+ }
+ StringRef Text(Begin, MinKeywordLength);
+
+ const bool IsGlobalModule = Text.starts_with("module");
+ if (!IsGlobalModule && !Text.starts_with("import") &&
+ !Text.starts_with("export"))
+ return false;
+
+ // Ensure the keyword has a proper ending and isn't part of a identifier
+ // or namespace. For this we might have to skip comments and line
+ // continuations.
+ while (*Ptr != '\0') {
+ if (isWhitespace(*Ptr) || (IsGlobalModule && *Ptr == ';'))
+ return true;
+ if (trySkipBlockComment(Ptr) || trySkipLineSplice(Ptr))
+ continue;
+ return false;
+ }
+
+ return false;
+}
+
+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);
+}
+
+} // anonymous namespace
+
+llvm::ErrorOr<bool>
+Driver::ScanInputsForCXXModuleUsage(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 (scanBufferForCXXModuleUsage(*Buffer)) {
+ 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");
@@ -4414,6 +4593,34 @@ 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)) {
+ Diags.Report(diag::remark_fmodules_driver_enabled);
+ // 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 = ScanInputsForCXXModuleUsage(Inputs);
+ if (!ErrOrScanResult) {
+ Diags.Report(diag::err_cannot_open_file)
+ << ErrOrScanResult.getError().message();
+ return;
+ }
+ UsesCXXModules = *ErrOrScanResult;
+ }
+ if (UsesCXXModules)
+ BuildExplicitModuleBuildActions(C, Args, Inputs, Actions);
+ return;
+ }
+
+ Driver::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) ||
@@ -4693,6 +4900,14 @@ void Driver::BuildActions(Compilation &C, DerivedArgList &Args,
Args.ClaimAllArgs(options::OPT_cl_ignored_Group);
}
+void Driver::BuildExplicitModuleBuildActions(Compilation &C,
+ llvm::opt::DerivedArgList &Args,
+ const InputList &Inputs,
+ ActionList &Actions) const {
+ Diags.Report(diag::remark_performing_explicit_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/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..9e0fc832003dd
--- /dev/null
+++ b/clang/test/Driver/modules-driver-cxx20-module-usage-scanner.cpp
@@ -0,0 +1,171 @@
+// 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 | 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 | 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 | 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 | 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 | 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 | 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 | 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 | 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 | 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>
+export module 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 | FileCheck %s --check-prefix=CHECK10
+// CHECK10: remark: found C++20 module usage in file '{{.*}}' [-Rmodules-driver]
+#define MACRO(a, \
+ b) \
+ call((a), \
+ (b)
+module;
+
+//--- 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 | 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 | 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 | FileCheck %s --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 | FileCheck %s --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 | 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 | 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 -ccc-print-phases \
+// RUN: %t/no-module-usage1.cpp %t/empty.cpp 2>&1 | FileCheck %s --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 -ccc-print-phases \
+// RUN: %t/no-module-usage2.cpp %t/empty.cpp 2>&1 | FileCheck %s --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 -ccc-print-phases \
+// RUN: %t/no-module-usage3.cpp %t/empty.cpp 2>&1 | FileCheck %s --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 -ccc-print-phases \
+// RUN: %t/no-module-usage-namespace-import.cpp %t/empty.cpp 2>&1 | FileCheck %s --check-prefix=CHECK20
+// CHECK20-NOT: remark: found C++20...
[truncated]
|
This PR is part of a series aimed at implementing native support for explicit module builds from the Clang driver. 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 help the driver determine whether to implicitly perform an explicit module build and will be enabled for any (modules-driver compatible) compilation with 2 or more inputs. 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, 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
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This PR is part of a series aimed at implementing native support for explicit module builds from the Clang driver.
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 help the driver determine whether to implicitly perform an explicit module build and will be enabled for any (modules-driver compatible) compilation with 2 or more inputs.
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, seehttps://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