Add -fno-implicit-modules.

If this flag is set, we error out when a module build is required. This is
useful in environments where all required modules are passed via -fmodule-file.

llvm-svn: 230006

clang/docs/Modules.rst

@@ -210,6 +210,12 @@ Command-line parameters
 ``-fno-modules-implicit-maps``
   Suppresses the implicit search for files called ``module.modulemap`` and similar. Instead, module files need to be explicitly specified via ``-fmodule-map-file`` or transitively used.
 
+``-fno-implicit-modules``
+  All modules used by the build must be specified with ``-fmodule-file``.
+
+``-fmodule-file=<file>``
+  Load the given precompiled module file.
+
 Module Semantics
 ================
 

clang/include/clang/Basic/DiagnosticCommonKinds.td

@@ -81,6 +81,9 @@ def err_deleted_non_function : Error<
   "only functions can have deleted definitions">;
 def err_module_not_found : Error<"module '%0' not found">, DefaultFatal;
 def err_module_not_built : Error<"could not build module '%0'">, DefaultFatal;
+def err_module_build_disabled: Error<
+  "module '%0' is needed but has not been provided, and implicit use of module "
+  "files is disabled">, DefaultFatal;
 def err_module_lock_failure : Error<
   "could not acquire lock file for module '%0'">, DefaultFatal;
 def err_module_lock_timeout : Error<

clang/include/clang/Basic/LangOptions.def

@@ -128,6 +128,7 @@ LANGOPT(ModulesSearchAll  , 1, 1, "search even non-imported modules to find unre
 COMPATIBLE_LANGOPT(ModulesStrictDeclUse, 1, 0, "require declaration of module uses and all headers to be in modules")
 LANGOPT(ModulesErrorRecovery, 1, 1, "automatically import modules as needed when performing error recovery")
 BENIGN_LANGOPT(ModulesImplicitMaps, 1, 1, "use files called module.modulemap implicitly as module maps")
+BENIGN_LANGOPT(ImplicitModules, 1, 1, "build modules that are not specified via -fmodule-file")
 COMPATIBLE_LANGOPT(Optimize          , 1, 0, "__OPTIMIZE__ predefined macro")
 COMPATIBLE_LANGOPT(OptimizeSize      , 1, 0, "__OPTIMIZE_SIZE__ predefined macro")
 LANGOPT(Static            , 1, 0, "__STATIC__ predefined macro (as opposed to __DYNAMIC__)")

clang/include/clang/Driver/Options.td

@@ -705,6 +705,9 @@ def fmodules_implicit_maps :
 def fno_modules_implicit_maps :
   Flag <["-"], "fno-modules-implicit-maps">,
   Group<f_Group>, Flags<[DriverOption, CC1Option]>;
+def fno_implicit_modules :
+  Flag <["-"], "fno-implicit-modules">,
+  Group<f_Group>, Flags<[DriverOption, CC1Option]>;
 def fretain_comments_from_system_headers : Flag<["-"], "fretain-comments-from-system-headers">, Group<f_Group>, Flags<[CC1Option]>;
 
 def fmudflapth : Flag<["-"], "fmudflapth">, Group<f_Group>;
@@ -765,6 +768,8 @@ def fno_modules_decluse : Flag <["-"], "fno-modules-decluse">, Group<f_Group>,
   Flags<[DriverOption]>;
 def fno_modules_strict_decluse : Flag <["-"], "fno-strict-modules-decluse">, Group<f_Group>,
   Flags<[DriverOption]>;
+def fimplicit_modules : Flag <["-"], "fimplicit-modules">, Group<f_Group>,
+  Flags<[DriverOption]>;
 def fno_ms_extensions : Flag<["-"], "fno-ms-extensions">, Group<f_Group>;
 def fno_ms_compatibility : Flag<["-"], "fno-ms-compatibility">, Group<f_Group>;
 def fno_delayed_template_parsing : Flag<["-"], "fno-delayed-template-parsing">, Group<f_Group>;

clang/lib/Driver/Tools.cpp

@@ -3925,6 +3925,12 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back("-fmodules-strict-decluse");
   }
 
+  // -fno-implicit-modules turns off implicitly compiling modules on demand.
+  if (!Args.hasFlag(options::OPT_fimplicit_modules,
+                    options::OPT_fno_implicit_modules)) {
+    CmdArgs.push_back("-fno-implicit-modules");
+  }
+
   // -fmodule-name specifies the module that is currently being built (or
   // used for header checking by -fmodule-maps).
   Args.AddLastArg(CmdArgs, options::OPT_fmodule_name);

clang/lib/Frontend/CompilerInstance.cpp

@@ -1378,6 +1378,12 @@ CompilerInstance::loadModule(SourceLocation ImportLoc,
 
     auto Override = ModuleFileOverrides.find(ModuleName);
     bool Explicit = Override != ModuleFileOverrides.end();
+    if (!Explicit && !getLangOpts().ImplicitModules) {
+      getDiagnostics().Report(ModuleNameLoc, diag::err_module_build_disabled)
+          << ModuleName;
+      ModuleBuildFailed = true;
+      return ModuleLoadResult();
+    }
 
     std::string ModuleFileName =
         Explicit ? Override->second

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1513,6 +1513,7 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
   Opts.ModulesErrorRecovery = !Args.hasArg(OPT_fno_modules_error_recovery);
   Opts.ModulesImplicitMaps = Args.hasFlag(OPT_fmodules_implicit_maps,
                                           OPT_fno_modules_implicit_maps, true);
+  Opts.ImplicitModules = !Args.hasArg(OPT_fno_implicit_modules);
   Opts.CharIsSigned = Opts.OpenCL || !Args.hasArg(OPT_fno_signed_char);
   Opts.WChar = Opts.CPlusPlus && !Args.hasArg(OPT_fno_wchar);
   Opts.ShortWChar = Args.hasFlag(OPT_fshort_wchar, OPT_fno_short_wchar, false);

clang/test/Modules/Inputs/no-implicit-builds/b.h

@@ -0,0 +1,6 @@
+#ifndef B_H
+#define B_H
+
+int b;
+
+#endif

clang/test/Modules/Inputs/no-implicit-builds/b.modulemap

@@ -0,0 +1,3 @@
+module "b" {
+  header "b.h"
+}

clang/test/Modules/no-implicit-builds.cpp

@@ -0,0 +1,33 @@
+// RUN: rm -rf %t
+
+// Produce an error if a module is needed, but not found.
+// RUN: %clang_cc1 -x c++ -std=c++11 -fmodules -fmodules-cache-path=%t \
+// RUN:     -fmodule-map-file=%S/Inputs/no-implicit-builds/b.modulemap \
+// RUN:     -fno-implicit-modules %s -verify
+
+// Compile the module and put it into the cache.
+// RUN: %clang_cc1 -x c++ -std=c++11 -fmodules -fmodules-cache-path=%t \
+// RUN:     -fmodule-map-file=%S/Inputs/no-implicit-builds/b.modulemap \
+// RUN:     %s -Rmodule-build 2>&1 | FileCheck --check-prefix=CHECK-CACHE-BUILD %s
+// CHECK-CACHE-BUILD: {{building module 'b'}}
+
+// Produce an error if a module is found in the cache but implicit modules is off.
+// Note that the command line must match the command line for the first check, otherwise
+// this check might not find the module in the cache and trivially succeed.
+// RUN: %clang_cc1 -x c++ -std=c++11 -fmodules -fmodules-cache-path=%t \
+// RUN:     -fmodule-map-file=%S/Inputs/no-implicit-builds/b.modulemap \
+// RUN:     %s -Rmodule-build -fno-implicit-modules -verify
+
+// Verify that we can still pass the module via -fmodule-file when implicit modules
+// are switched off:
+// - First, explicitly compile the module:
+// RUN: %clang_cc1 -x c++ -std=c++11 -fmodules -fmodule-name=b -o %t/b.pcm \
+// RUN:     -emit-module %S/Inputs/no-implicit-builds/b.modulemap \
+// RUN:     -fno-implicit-modules
+//
+// - Next, verify that we can load it:
+// RUN: %clang_cc1 -x c++ -std=c++11 -fmodules -fmodule-file=%t/b.pcm \
+// RUN:     -fmodule-map-file=%S/Inputs/no-implicit-builds/b.modulemap \
+// RUN:     -fno-implicit-modules %s
+
+#include "Inputs/no-implicit-builds/b.h"  // expected-error {{is needed but has not been provided}}