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Jan 20, 2022
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[interop] add an option to emit C++ header interface for a module #40923

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2 changes: 2 additions & 0 deletions include/swift/AST/DiagnosticsFrontend.def
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Expand Up @@ -119,6 +119,8 @@ ERROR(error_mode_cannot_emit_reference_dependencies,none,
"this mode does not support emitting reference dependency files", ())
ERROR(error_mode_cannot_emit_header,none,
"this mode does not support emitting Objective-C headers", ())
ERROR(error_mode_cannot_emit_cxx_header,none,
"this mode does not support emitting C++ headers", ())
ERROR(error_mode_cannot_emit_loaded_module_trace,none,
"this mode does not support emitting the loaded module trace", ())
ERROR(error_mode_cannot_emit_module,none,
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27 changes: 21 additions & 6 deletions include/swift/Basic/SupplementaryOutputPaths.h
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Expand Up @@ -31,6 +31,17 @@ struct SupplementaryOutputPaths {
/// \sa swift::printAsObjC
std::string ObjCHeaderOutputPath;

/// The path to which we should emit a C++ header for the module.
///
/// Currently only makes sense when the compiler has whole module knowledge.
/// The modes for which it makes sense include both WMO and the "merge
/// modules" job that happens after the normal compilation jobs. That's where
/// the header is emitted in single-file mode, since it needs whole-module
/// information.
///
/// \sa swift::printAsCxx
std::string CxxHeaderOutputPath;

/// The path to which we should emit a serialized module.
/// It is valid whenever there are any inputs.
///
Expand Down Expand Up @@ -160,7 +171,9 @@ struct SupplementaryOutputPaths {
/// Apply a given function for each existing (non-empty string) supplementary output
void forEachSetOutput(llvm::function_ref<void(const std::string&)> fn) const {
if (!ObjCHeaderOutputPath.empty())
fn(ObjCHeaderOutputPath);
fn(ObjCHeaderOutputPath);
if (!CxxHeaderOutputPath.empty())
fn(CxxHeaderOutputPath);
if (!ModuleOutputPath.empty())
fn(ModuleOutputPath);
if (!ModuleSourceInfoOutputPath.empty())
Expand Down Expand Up @@ -196,14 +209,16 @@ struct SupplementaryOutputPaths {
}

bool empty() const {
return ObjCHeaderOutputPath.empty() && ModuleOutputPath.empty() &&
ModuleDocOutputPath.empty() && DependenciesFilePath.empty() &&
return ObjCHeaderOutputPath.empty() && CxxHeaderOutputPath.empty() &&
ModuleOutputPath.empty() && ModuleDocOutputPath.empty() &&
DependenciesFilePath.empty() &&
ReferenceDependenciesFilePath.empty() &&
SerializedDiagnosticsPath.empty() && LoadedModuleTracePath.empty() &&
TBDPath.empty() && ModuleInterfaceOutputPath.empty() &&
ModuleSourceInfoOutputPath.empty() && ABIDescriptorOutputPath.empty() &&
ModuleSemanticInfoOutputPath.empty() &&
YAMLOptRecordPath.empty() && BitstreamOptRecordPath.empty();
ModuleSourceInfoOutputPath.empty() &&
ABIDescriptorOutputPath.empty() &&
ModuleSemanticInfoOutputPath.empty() && YAMLOptRecordPath.empty() &&
BitstreamOptRecordPath.empty();
}
};
} // namespace swift
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1 change: 1 addition & 0 deletions include/swift/Frontend/Frontend.h
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Expand Up @@ -388,6 +388,7 @@ class CompilerInvocation {
std::string getOutputFilenameForAtMostOnePrimary() const;
std::string getMainInputFilenameForDebugInfoForAtMostOnePrimary() const;
std::string getObjCHeaderOutputPathForAtMostOnePrimary() const;
std::string getCxxHeaderOutputPathForAtMostOnePrimary() const;
std::string getModuleOutputPathForAtMostOnePrimary() const;
std::string
getReferenceDependenciesFilePathForPrimary(StringRef filename) const;
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1 change: 1 addition & 0 deletions include/swift/Frontend/FrontendInputsAndOutputs.h
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Expand Up @@ -250,6 +250,7 @@ class FrontendInputsAndOutputs {
bool hasDependenciesPath() const;
bool hasReferenceDependenciesPath() const;
bool hasObjCHeaderOutputPath() const;
bool hasCxxHeaderOutputPath() const;
bool hasLoadedModuleTracePath() const;
bool hasModuleOutputPath() const;
bool hasModuleDocOutputPath() const;
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2 changes: 1 addition & 1 deletion include/swift/Frontend/FrontendOptions.h
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Expand Up @@ -450,7 +450,7 @@ class FrontendOptions {
private:
static bool canActionEmitDependencies(ActionType);
static bool canActionEmitReferenceDependencies(ActionType);
static bool canActionEmitObjCHeader(ActionType);
static bool canActionEmitClangHeader(ActionType);
static bool canActionEmitLoadedModuleTrace(ActionType);
static bool canActionEmitModule(ActionType);
static bool canActionEmitModuleDoc(ActionType);
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8 changes: 8 additions & 0 deletions include/swift/Option/Options.td
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Expand Up @@ -532,6 +532,14 @@ def emit_objc_header_path : Separate<["-"], "emit-objc-header-path">,
SupplementaryOutput]>,
MetaVarName<"<path>">, HelpText<"Emit an Objective-C header file to <path>">;

def emit_cxx_header : Flag<["-"], "emit-cxx-header">,
Flags<[FrontendOption, NoInteractiveOption, SupplementaryOutput]>,
HelpText<"Emit a C++ header file">;
def emit_cxx_header_path : Separate<["-"], "emit-cxx-header-path">,
Flags<[FrontendOption, NoInteractiveOption, ArgumentIsPath,
SupplementaryOutput]>,
MetaVarName<"<path>">, HelpText<"Emit a C++ header file to <path>">;

def static : Flag<["-"], "static">,
Flags<[FrontendOption, ModuleInterfaceOption, NoInteractiveOption]>,
HelpText<"Make this module statically linkable and make the output of -emit-library a static library.">;
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5 changes: 5 additions & 0 deletions include/swift/PrintAsObjC/PrintAsObjC.h
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Expand Up @@ -26,6 +26,11 @@ namespace swift {
///
/// Returns true on error.
bool printAsObjC(raw_ostream &out, ModuleDecl *M, StringRef bridgingHeader);

/// Print the C++-compatible declarations in a module as a Clang header.
///
/// Returns true on error.
bool printAsCXX(raw_ostream &os, ModuleDecl *M);
}

#endif
7 changes: 6 additions & 1 deletion lib/Frontend/ArgsToFrontendOptionsConverter.cpp
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Expand Up @@ -623,11 +623,16 @@ bool ArgsToFrontendOptionsConverter::checkUnusedSupplementaryOutputPaths()
diag::error_mode_cannot_emit_reference_dependencies);
return true;
}
if (!FrontendOptions::canActionEmitObjCHeader(Opts.RequestedAction) &&
if (!FrontendOptions::canActionEmitClangHeader(Opts.RequestedAction) &&
Opts.InputsAndOutputs.hasObjCHeaderOutputPath()) {
Diags.diagnose(SourceLoc(), diag::error_mode_cannot_emit_header);
return true;
}
if (!FrontendOptions::canActionEmitClangHeader(Opts.RequestedAction) &&
Opts.InputsAndOutputs.hasCxxHeaderOutputPath()) {
Diags.diagnose(SourceLoc(), diag::error_mode_cannot_emit_cxx_header);
return true;
}
if (!FrontendOptions::canActionEmitLoadedModuleTrace(Opts.RequestedAction) &&
Opts.InputsAndOutputs.hasLoadedModuleTracePath()) {
Diags.diagnose(SourceLoc(),
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35 changes: 22 additions & 13 deletions lib/Frontend/ArgsToFrontendOutputsConverter.cpp
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Expand Up @@ -310,6 +310,8 @@ SupplementaryOutputPathsComputer::getSupplementaryOutputPathsFromArguments()

auto objCHeaderOutput = getSupplementaryFilenamesFromArguments(
options::OPT_emit_objc_header_path);
auto cxxHeaderOutput =
getSupplementaryFilenamesFromArguments(options::OPT_emit_cxx_header_path);
auto moduleOutput =
getSupplementaryFilenamesFromArguments(options::OPT_emit_module_path);
auto moduleDocOutput =
Expand Down Expand Up @@ -339,8 +341,8 @@ SupplementaryOutputPathsComputer::getSupplementaryOutputPathsFromArguments()
options::OPT_emit_module_semantic_info_path);
auto optRecordOutput = getSupplementaryFilenamesFromArguments(
options::OPT_save_optimization_record_path);
if (!objCHeaderOutput || !moduleOutput || !moduleDocOutput ||
!dependenciesFile || !referenceDependenciesFile ||
if (!objCHeaderOutput || !cxxHeaderOutput || !moduleOutput ||
!moduleDocOutput || !dependenciesFile || !referenceDependenciesFile ||
!serializedDiagnostics || !fixItsOutput || !loadedModuleTrace || !TBD ||
!moduleInterfaceOutput || !privateModuleInterfaceOutput ||
!moduleSourceInfoOutput || !moduleSummaryOutput || !abiDescriptorOutput ||
Expand All @@ -354,6 +356,7 @@ SupplementaryOutputPathsComputer::getSupplementaryOutputPathsFromArguments()
for (unsigned i = 0; i < N; ++i) {
SupplementaryOutputPaths sop;
sop.ObjCHeaderOutputPath = (*objCHeaderOutput)[i];
sop.CxxHeaderOutputPath = (*cxxHeaderOutput)[i];
sop.ModuleOutputPath = (*moduleOutput)[i];
sop.ModuleDocOutputPath = (*moduleDocOutput)[i];
sop.DependenciesFilePath = (*dependenciesFile)[i];
Expand Down Expand Up @@ -439,6 +442,11 @@ SupplementaryOutputPathsComputer::computeOutputPathsForOneInput(
file_types::TY_ObjCHeader, "",
defaultSupplementaryOutputPathExcludingExtension);

auto cxxHeaderOutputPath = determineSupplementaryOutputFilename(
OPT_emit_cxx_header, pathsFromArguments.CxxHeaderOutputPath,
file_types::TY_ObjCHeader, "",
defaultSupplementaryOutputPathExcludingExtension);

auto loadedModuleTracePath = determineSupplementaryOutputFilename(
OPT_emit_loaded_module_trace, pathsFromArguments.LoadedModuleTracePath,
file_types::TY_ModuleTrace, "",
Expand Down Expand Up @@ -493,6 +501,7 @@ SupplementaryOutputPathsComputer::computeOutputPathsForOneInput(

SupplementaryOutputPaths sop;
sop.ObjCHeaderOutputPath = objcHeaderOutputPath;
sop.CxxHeaderOutputPath = cxxHeaderOutputPath;
sop.ModuleOutputPath = moduleOutputPath;
sop.ModuleDocOutputPath = moduleDocOutputPath;
sop.DependenciesFilePath = dependenciesFilePath;
Expand Down Expand Up @@ -578,6 +587,7 @@ createFromTypeToPathMap(const TypeToPathMap *map) {
return paths;
const std::pair<file_types::ID, std::string &> typesAndStrings[] = {
{file_types::TY_ObjCHeader, paths.ObjCHeaderOutputPath},
{file_types::TY_ObjCHeader, paths.CxxHeaderOutputPath},
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This is a problem, because we have two different outputs associated with the same entry in the output file map, so we'll end up writing both the ObjC and C++ header to the same place. I've fixed the issue via #41015, but I think we should reconsider having separate ObjC vs. C++ generated headers. It's a mess for the build system, and what would we do about Objective-C++? Instead, I think we should generate a single header that uses #ifdefs to appropriately compile as C/ObjC/C++/ObjC++.

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Hi Doug, thanks for fixing this, and sorry about the breakage. I'm not sure if we would like to generate a single header, instead we actually would prefer to generate multiple C++ headers as they will be target-specific, one per target, and then have the build system create a unified C++ header one from them. Do you think that would be a reasonable idea, and should we even support path map in that case? Also, I don't believe we want to emit Objective-C++ headers, as that would be ambiguous - we would either want to emit Objective-C or C++, and then the programmer can import their preferred interface into Objective-C++ as desired.

{file_types::TY_SwiftModuleFile, paths.ModuleOutputPath},
{file_types::TY_SwiftModuleDocFile, paths.ModuleDocOutputPath},
{file_types::TY_SwiftSourceInfoFile, paths.ModuleSourceInfoOutputPath},
Expand Down Expand Up @@ -606,17 +616,16 @@ createFromTypeToPathMap(const TypeToPathMap *map) {
Optional<std::vector<SupplementaryOutputPaths>>
SupplementaryOutputPathsComputer::readSupplementaryOutputFileMap() const {
if (Arg *A = Args.getLastArg(
options::OPT_emit_objc_header_path,
options::OPT_emit_module_path,
options::OPT_emit_module_doc_path,
options::OPT_emit_dependencies_path,
options::OPT_emit_reference_dependencies_path,
options::OPT_serialize_diagnostics_path,
options::OPT_emit_loaded_module_trace_path,
options::OPT_emit_module_interface_path,
options::OPT_emit_private_module_interface_path,
options::OPT_emit_module_source_info_path,
options::OPT_emit_tbd_path)) {
options::OPT_emit_objc_header_path, options::OPT_emit_cxx_header_path,
options::OPT_emit_module_path, options::OPT_emit_module_doc_path,
options::OPT_emit_dependencies_path,
options::OPT_emit_reference_dependencies_path,
options::OPT_serialize_diagnostics_path,
options::OPT_emit_loaded_module_trace_path,
options::OPT_emit_module_interface_path,
options::OPT_emit_private_module_interface_path,
options::OPT_emit_module_source_info_path,
options::OPT_emit_tbd_path)) {
Diags.diagnose(SourceLoc(),
diag::error_cannot_have_supplementary_outputs,
A->getSpelling(), "-supplementary-output-file-map");
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5 changes: 5 additions & 0 deletions lib/Frontend/Frontend.cpp
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Expand Up @@ -96,6 +96,11 @@ CompilerInvocation::getObjCHeaderOutputPathForAtMostOnePrimary() const {
return getPrimarySpecificPathsForAtMostOnePrimary()
.SupplementaryOutputs.ObjCHeaderOutputPath;
}
std::string
CompilerInvocation::getCxxHeaderOutputPathForAtMostOnePrimary() const {
return getPrimarySpecificPathsForAtMostOnePrimary()
.SupplementaryOutputs.CxxHeaderOutputPath;
}
std::string CompilerInvocation::getModuleOutputPathForAtMostOnePrimary() const {
return getPrimarySpecificPathsForAtMostOnePrimary()
.SupplementaryOutputs.ModuleOutputPath;
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6 changes: 6 additions & 0 deletions lib/Frontend/FrontendInputsAndOutputs.cpp
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Expand Up @@ -467,6 +467,12 @@ bool FrontendInputsAndOutputs::hasObjCHeaderOutputPath() const {
return outs.ObjCHeaderOutputPath;
});
}
bool FrontendInputsAndOutputs::hasCxxHeaderOutputPath() const {
return hasSupplementaryOutputPath(
[](const SupplementaryOutputPaths &outs) -> const std::string & {
return outs.CxxHeaderOutputPath;
});
}
bool FrontendInputsAndOutputs::hasLoadedModuleTracePath() const {
return hasSupplementaryOutputPath(
[](const SupplementaryOutputPaths &outs) -> const std::string & {
Expand Down
13 changes: 6 additions & 7 deletions lib/Frontend/FrontendOptions.cpp
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Expand Up @@ -231,12 +231,11 @@ void FrontendOptions::forAllOutputPaths(
}
const SupplementaryOutputPaths &outs =
input.getPrimarySpecificPaths().SupplementaryOutputs;
const std::string *outputs[] = {&outs.ModuleOutputPath,
&outs.ModuleDocOutputPath,
&outs.ModuleInterfaceOutputPath,
&outs.PrivateModuleInterfaceOutputPath,
&outs.ObjCHeaderOutputPath,
&outs.ModuleSourceInfoOutputPath};
const std::string *outputs[] = {
&outs.ModuleOutputPath, &outs.ModuleDocOutputPath,
&outs.ModuleInterfaceOutputPath, &outs.PrivateModuleInterfaceOutputPath,
&outs.ObjCHeaderOutputPath, &outs.CxxHeaderOutputPath,
&outs.ModuleSourceInfoOutputPath};
for (const std::string *next : outputs) {
if (!next->empty())
fn(*next);
Expand Down Expand Up @@ -449,7 +448,7 @@ bool FrontendOptions::canActionEmitModuleSummary(ActionType action) {
llvm_unreachable("unhandled action");
}

bool FrontendOptions::canActionEmitObjCHeader(ActionType action) {
bool FrontendOptions::canActionEmitClangHeader(ActionType action) {
switch (action) {
case ActionType::NoneAction:
case ActionType::Parse:
Expand Down
22 changes: 22 additions & 0 deletions lib/FrontendTool/FrontendTool.cpp
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Expand Up @@ -186,6 +186,22 @@ static bool printAsObjCIfNeeded(StringRef outputPath, ModuleDecl *M,
});
}

/// Prints the C++ "generated header" interface for \p M to \p
/// outputPath.
///
/// ...unless \p outputPath is empty, in which case it does nothing.
///
/// \returns true if there were any errors
///
/// \see swift::printAsCxx
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Nit: that function is spelled swift::printAsCXX with capital XX :)

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Good catch, I'll fix it up in the next patch.

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#40934

static bool printAsCxxIfNeeded(StringRef outputPath, ModuleDecl *M) {
if (outputPath.empty())
return false;
return withOutputFile(
M->getDiags(), outputPath,
[&](raw_ostream &os) -> bool { return printAsCXX(os, M); });
}

/// Prints the stable module interface for \p M to \p outputPath.
///
/// ...unless \p outputPath is empty, in which case it does nothing.
Expand Down Expand Up @@ -826,6 +842,12 @@ static bool emitAnyWholeModulePostTypeCheckSupplementaryOutputs(
Invocation.getObjCHeaderOutputPathForAtMostOnePrimary(),
Instance.getMainModule(), BridgingHeaderPathForPrint);
}
if ((!Context.hadError() || opts.AllowModuleWithCompilerErrors) &&
opts.InputsAndOutputs.hasCxxHeaderOutputPath()) {
hadAnyError |= printAsCxxIfNeeded(
Invocation.getCxxHeaderOutputPathForAtMostOnePrimary(),
Instance.getMainModule());
}

// Only want the header if there's been any errors, ie. there's not much
// point outputting a swiftinterface for an invalid module
Expand Down
18 changes: 16 additions & 2 deletions lib/PrintAsObjC/PrintAsObjC.cpp
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Expand Up @@ -389,6 +389,10 @@ static void writeEpilogue(raw_ostream &os) {
"#endif\n";
}

static std::string computeMacroGuard(const ModuleDecl *M) {
return (llvm::Twine(M->getNameStr().upper()) + "_SWIFT_H").str();
}

bool swift::printAsObjC(raw_ostream &os, ModuleDecl *M,
StringRef bridgingHeader) {
llvm::PrettyStackTraceString trace("While generating Objective-C header");
Expand All @@ -397,12 +401,22 @@ bool swift::printAsObjC(raw_ostream &os, ModuleDecl *M,
std::string moduleContentsBuf;
llvm::raw_string_ostream moduleContents{moduleContentsBuf};
printModuleContentsAsObjC(moduleContents, imports, *M);
std::string macroGuard = (llvm::Twine(M->getNameStr().upper()) + "_SWIFT_H").str();
writePrologue(os, M->getASTContext(), macroGuard);
writePrologue(os, M->getASTContext(), computeMacroGuard(M));
writeImports(os, imports, *M, bridgingHeader);
writePostImportPrologue(os, *M);
os << moduleContents.str();
writeEpilogue(os);

return false;
}

bool swift::printAsCXX(raw_ostream &os, ModuleDecl *M) {
llvm::PrettyStackTraceString trace("While generating C++ header");

writePrologue(os, M->getASTContext(), computeMacroGuard(M));
writePostImportPrologue(os, *M);
// TODO (Alex): emit module contents.
writeEpilogue(os);

return false;
}
7 changes: 7 additions & 0 deletions test/Frontend/supplementary-output-support.swift
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Expand Up @@ -24,6 +24,13 @@
// RUN: not %target-swift-frontend -resolve-imports -emit-objc-header %s 2>&1 | %FileCheck -check-prefix=RESOLVE_IMPORTS_NO_OBJC_HEADER %s
// RESOLVE_IMPORTS_NO_OBJC_HEADER: error: this mode does not support emitting Objective-C headers{{$}}

// RUN: not %target-swift-frontend -parse -emit-cxx-header %s 2>&1 | %FileCheck -check-prefix=PARSE_NO_CXX_HEADER %s
// PARSE_NO_CXX_HEADER: error: this mode does not support emitting C++ headers{{$}}
// RUN: not %target-swift-frontend -dump-ast -emit-cxx-header %s 2>&1 | %FileCheck -check-prefix=DUMP_NO_CXX_HEADER %s
// DUMP_NO_CXX_HEADER: error: this mode does not support emitting C++ headers{{$}}
// RUN: not %target-swift-frontend -resolve-imports -emit-cxx-header %s 2>&1 | %FileCheck -check-prefix=RESOLVE_IMPORTS_NO_CXX_HEADER %s
// RESOLVE_IMPORTS_NO_CXX_HEADER: error: this mode does not support emitting C++ headers{{$}}

// RUN: not %target-swift-frontend -parse -emit-module-interface-path %t %s 2>&1 | %FileCheck -check-prefix=PARSE_NO_INTERFACE %s
// PARSE_NO_INTERFACE: error: this mode does not support emitting module interface files{{$}}
// RUN: not %target-swift-frontend -emit-silgen -emit-module-interface-path %t %s 2>&1 | %FileCheck -check-prefix=SILGEN_NO_INTERFACE %s
Expand Down
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