<rdar://problem/10796651> Introduce configuration macros into module maps.

Configuration macros are macros that are intended to alter how a
module works, such that we need to build different module variants
for different values of these macros. A module can declare its
configuration macros, in which case we will complain if the definition
of a configation macro on the command line (or lack thereof) differs
from the current preprocessor state at the point where the module is
imported. This should eliminate some surprises when enabling modules,
because "#define CONFIG_MACRO ..." followed by "#include
<module/header.h>" would silently ignore the CONFIG_MACRO setting. At
least it will no longer be silent about it.

Configuration macros are eventually intended to help reduce the number
of module variants that need to be built. When the list of
configuration macros for a module is exhaustive, we only need to
consider the settings for those macros when building/finding the
module, which can help isolate modules for various project-specific -D
flags that should never affect how modules are build (but currently do).



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177466 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 30 insertions, 5 deletions

diff --git a/include/clang/Basic/DiagnosticFrontendKinds.td b/include/clang/Basic/DiagnosticFrontendKinds.td
index 230a6d3dcc..111622e0fe 100644
--- a/include/clang/Basic/DiagnosticFrontendKinds.td
+++ b/include/clang/Basic/DiagnosticFrontendKinds.td
@@ -137,5 +137,11 @@ def warn_missing_submodule : Warning<"missing submodule '%0'">,
 def err_module_map_temp_file : Error<
   "unable to write temporary module map file '%0'">, DefaultFatal;
 def err_module_unavailable : Error<"module '%0' requires feature '%1'">;
-
+def warn_module_config_macro_undef : Warning<
+  "%select{definition|#undef}0 of configuration macro '%1' has no effect on "
+  "the import of '%2'; pass '%select{-D%1=...|-U%1}0' on the command line "
+  "to configure the module">,
+  InGroup<ConfigMacros>;
+def note_module_def_undef_here : Note<
+  "macro was %select{defined|#undef'd}0 here">;
 }
diff --git a/include/clang/Basic/DiagnosticGroups.td b/include/clang/Basic/DiagnosticGroups.td
index 0f127bf2e2..9af83b10a7 100644
--- a/include/clang/Basic/DiagnosticGroups.td
+++ b/include/clang/Basic/DiagnosticGroups.td
@@ -47,6 +47,7 @@ def CastAlign : DiagGroup<"cast-align">;
 def : DiagGroup<"cast-qual">;
 def : DiagGroup<"char-align">;
 def Comment : DiagGroup<"comment">;
+def ConfigMacros : DiagGroup<"config-macros">;
 def : DiagGroup<"ctor-dtor-privacy">;
 def GNUDesignator : DiagGroup<"gnu-designator">;
 
diff --git a/include/clang/Basic/DiagnosticLexKinds.td b/include/clang/Basic/DiagnosticLexKinds.td
index 7f66a87d61..80c52492f4 100644
--- a/include/clang/Basic/DiagnosticLexKinds.td
+++ b/include/clang/Basic/DiagnosticLexKinds.td
@@ -532,6 +532,10 @@ def err_mmap_export_module_id : Error<
   "expected an exported module name or '*'">;
 def err_mmap_expected_library_name : Error<
   "expected %select{library|framework}0 name as a string">;
+def err_mmap_config_macro_submodule : Error<
+  "configuration macros are only allowed on top-level modules">;
+def err_mmap_expected_config_macro : Error<
+  "expected configuration macro name after ','">;
 def err_mmap_missing_module_unqualified : Error<
   "no module named '%0' visible from '%1'">;
 def err_mmap_missing_module_qualified : Error<
diff --git a/include/clang/Basic/Module.h b/include/clang/Basic/Module.h
index 5f081e0f56..2add58019f 100644
--- a/include/clang/Basic/Module.h
+++ b/include/clang/Basic/Module.h
@@ -119,7 +119,14 @@ public:
   /// \brief Whether, when inferring submodules, the inferr submodules should
   /// export all modules they import (e.g., the equivalent of "export *").
   unsigned InferExportWildcard : 1;
-  
+
+  /// \brief Whether the set of configuration macros is exhaustive.
+  ///
+  /// When the set of configuration macros is exhaustive, meaning
+  /// that no identifier not in this list should affect how the module is
+  /// built.
+  unsigned ConfigMacrosExhaustive : 1;
+
   /// \brief Describes the visibility of the various names within a
   /// particular module.
   enum NameVisibilityKind {
@@ -190,6 +197,10 @@ public:
   /// an entity from this module is used.
   llvm::SmallVector<LinkLibrary, 2> LinkLibraries;
 
+  /// \brief The set of "configuration macros", which are macros that
+  /// (intentionally) change how this module is built.
+  std::vector<std::string> ConfigMacros;
+
   /// \brief Construct a top-level module.
   explicit Module(StringRef Name, SourceLocation DefinitionLoc,
                   bool IsFramework)
@@ -197,7 +208,8 @@ public:
       IsAvailable(true), IsFromModuleFile(false), IsFramework(IsFramework), 
       IsExplicit(false), IsSystem(false),
       InferSubmodules(false), InferExplicitSubmodules(false),
-      InferExportWildcard(false), NameVisibility(Hidden) { }
+      InferExportWildcard(false), ConfigMacrosExhaustive(false),
+      NameVisibility(Hidden) { }
   
   /// \brief Construct a new module or submodule.
   Module(StringRef Name, SourceLocation DefinitionLoc, Module *Parent, 
@@ -328,7 +340,7 @@ public:
   ///
   /// \returns The submodule if found, or NULL otherwise.
   Module *findSubmodule(StringRef Name) const;
-  
+
   typedef std::vector<Module *>::iterator submodule_iterator;
   typedef std::vector<Module *>::const_iterator submodule_const_iterator;
   
diff --git a/include/clang/Serialization/ASTBitCodes.h b/include/clang/Serialization/ASTBitCodes.h
index 93c5c073d5..2669d8e6d7 100644
--- a/include/clang/Serialization/ASTBitCodes.h
+++ b/include/clang/Serialization/ASTBitCodes.h
@@ -609,7 +609,9 @@ namespace clang {
       /// from this submodule.
       SUBMODULE_EXCLUDED_HEADER = 9,
       /// \brief Specifies a library or framework to link against.
-      SUBMODULE_LINK_LIBRARY = 10
+      SUBMODULE_LINK_LIBRARY = 10,
+      /// \brief Specifies a configuration macro for this module.
+      SUBMODULE_CONFIG_MACRO = 11
     };
 
     /// \brief Record types used within a comments block.