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🍒[clang][Modules] Respect -fno-cxx-modules as a driver flag (#150349) #11069

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Merged
merged 1 commit into from
Jul 31, 2025
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🍒[clang][Modules] Respect -fno-cxx-modules as a driver flag (#150349) #11069

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11 changes: 7 additions & 4 deletions clang/lib/Driver/ToolChains/Clang.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3946,17 +3946,17 @@ static bool RenderModulesOptions(Compilation &C, const Driver &D,
const ArgList &Args, const InputInfo &Input,
const InputInfo &Output, bool HaveStd20,
ArgStringList &CmdArgs) {
bool IsCXX = types::isCXX(Input.getType());
bool HaveStdCXXModules = IsCXX && HaveStd20;
const bool IsCXX = types::isCXX(Input.getType());
const bool HaveStdCXXModules = IsCXX && HaveStd20;
bool HaveModules = HaveStdCXXModules;

// -fmodules enables the use of precompiled modules (off by default).
// Users can pass -fno-cxx-modules to turn off modules support for
// C++/Objective-C++ programs.
const bool AllowedInCXX = Args.hasFlag(options::OPT_fcxx_modules,
options::OPT_fno_cxx_modules, true);
bool HaveClangModules = false;
if (Args.hasFlag(options::OPT_fmodules, options::OPT_fno_modules, false)) {
bool AllowedInCXX = Args.hasFlag(options::OPT_fcxx_modules,
options::OPT_fno_cxx_modules, true);
if (AllowedInCXX || !IsCXX) {
CmdArgs.push_back("-fmodules");
HaveClangModules = true;
Expand All @@ -3965,6 +3965,9 @@ static bool RenderModulesOptions(Compilation &C, const Driver &D,

HaveModules |= HaveClangModules;

if (HaveModules && !AllowedInCXX)
CmdArgs.push_back("-fno-cxx-modules");

// -fmodule-maps enables implicit reading of module map files. By default,
// this is enabled if we are using Clang's flavor of precompiled modules.
if (Args.hasFlag(options::OPT_fimplicit_module_maps,
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3 changes: 3 additions & 0 deletions clang/test/Driver/modules.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,9 @@
// RUN: %clang -fmodules -fno-cxx-modules -### %s 2>&1 | FileCheck -check-prefix=CHECK-NO-MODULES %s
// CHECK-NO-MODULES-NOT: -fmodules

// RUN: %clang -std=c++20 -fno-cxx-modules -### %s 2>&1 | FileCheck -check-prefix=CHECK-NO-CPP-20-MODULES %s
// CHECK-NO-CPP-20-MODULES: -fno-cxx-modules

// RUN: %clang -fmodules -### %s 2>&1 | FileCheck -check-prefix=CHECK-HAS-MODULES %s
// RUN: %clang -fmodules -fno-cxx-modules -fcxx-modules -### %s 2>&1 | FileCheck -check-prefix=CHECK-HAS-MODULES %s
// CHECK-HAS-MODULES: -fmodules
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