[modules] When diagnosing a missing module import, suggest adding a #include if

the current language doesn't have an import syntax and we can figure out a
suitable file to include.

llvm-svn: 267802

4 files changed, 31 insertions, 3 deletions

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 4e2a0349645..afa741077c3 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8262,6 +8262,10 @@ def err_module_private_local_class : Error<
 def err_module_unimported_use : Error<
   "%select{declaration|definition|default argument}0 of %1 must be imported "
   "from module '%2' before it is required">;
+def err_module_unimported_use_header : Error<
+  "missing '#include %3'; "
+  "%select{declaration|definition|default argument}0 of %1 must be imported "
+  "from module '%2' before it is required">;
 def err_module_unimported_use_multiple : Error<
   "%select{declaration|definition|default argument}0 of %1 must be imported "
   "from one of the following modules before it is required:%2">;
diff --git a/clang/include/clang/Lex/HeaderSearch.h b/clang/include/clang/Lex/HeaderSearch.h
index 6d592e19c06..458f07e5e44 100644
--- a/clang/include/clang/Lex/HeaderSearch.h
+++ b/clang/include/clang/Lex/HeaderSearch.h
@@ -634,13 +634,18 @@ public:
   /// \brief Retrieve a uniqued framework name.
   StringRef getUniqueFrameworkName(StringRef Framework);
   
+  /// \brief Suggest a path by which the specified file could be found, for
+  /// use in diagnostics to suggest a #include.
+  ///
+  /// \param IsSystem If non-null, filled in to indicate whether the suggested
+  ///        path is relative to a system header directory.
+  std::string suggestPathToFileForDiagnostics(const FileEntry *File,
+                                              bool *IsSystem = nullptr);
+
   void PrintStats();
   
   size_t getTotalMemory() const;
 
-  static std::string NormalizeDashIncludePath(StringRef File,
-                                              FileManager &FileMgr);
-
 private:
   /// \brief Describes what happened when we tried to load a module map file.
   enum LoadModuleMapResult {
diff --git a/clang/include/clang/Lex/ModuleMap.h b/clang/include/clang/Lex/ModuleMap.h
index d8d374b622b..b8cfb8faa8d 100644
--- a/clang/include/clang/Lex/ModuleMap.h
+++ b/clang/include/clang/Lex/ModuleMap.h
@@ -130,6 +130,12 @@ public:
       return getModule()->isAvailable();
     }
 
+    /// \brief Whether this header is accessible from the specified module.
+    bool isAccessibleFrom(Module *M) const {
+      return !(getRole() & PrivateHeader) ||
+             (M && M->getTopLevelModule() == getModule()->getTopLevelModule());
+    }
+
     // \brief Whether this known header is valid (i.e., it has an
     // associated module).
     explicit operator bool() const {
diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
index 817c09fcdbc..30cc37f6f88 100644
--- a/clang/include/clang/Lex/Preprocessor.h
+++ b/clang/include/clang/Lex/Preprocessor.h
@@ -1891,6 +1891,19 @@ public:
   /// directly or indirectly.
   Module *getModuleContainingLocation(SourceLocation Loc);
 
+  /// \brief We want to produce a diagnostic at location IncLoc concerning a
+  /// missing module import.
+  ///
+  /// \param IncLoc The location at which the missing import was detected.
+  /// \param MLoc A location within the desired module at which some desired
+  ///        effect occurred (eg, where a desired entity was declared).
+  ///
+  /// \return A file that can be #included to import a module containing MLoc.
+  ///         Null if no such file could be determined or if a #include is not
+  ///         appropriate.
+  const FileEntry *getModuleHeaderToIncludeForDiagnostics(SourceLocation IncLoc,
+                                                          SourceLocation MLoc);
+
 private:
   // Macro handling.
   void HandleDefineDirective(Token &Tok, bool ImmediatelyAfterTopLevelIfndef);