Keep track of modules that have failed to build. If we encounter an

import of that module elsewhere, don't try to build the module again:
it won't work, and the experience is quite dreadful. We track this
information somewhat globally, shared among all of the related
CompilerInvocations used to build modules on-the-fly, so that a
particular Clang instance will only try to build a given module once.

Fixes <rdar://problem/12552849>.




git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@168961 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 61 insertions, 14 deletions

diff --git a/include/clang/Frontend/ASTUnit.h b/include/clang/Frontend/ASTUnit.h
index 5e409bd7ed..ac9a0461b8 100644
--- a/include/clang/Frontend/ASTUnit.h
+++ b/include/clang/Frontend/ASTUnit.h
@@ -830,11 +830,12 @@ public:
   /// \returns True if an error occurred, false otherwise.
   bool serialize(raw_ostream &OS);
   
-  virtual Module *loadModule(SourceLocation ImportLoc, ModuleIdPath Path,
-                             Module::NameVisibilityKind Visibility,
-                             bool IsInclusionDirective) {
+  virtual ModuleLoadResult loadModule(SourceLocation ImportLoc,
+                                      ModuleIdPath Path,
+                                      Module::NameVisibilityKind Visibility,
+                                      bool IsInclusionDirective) {
     // ASTUnit doesn't know how to load modules (not that this matters).
-    return 0;
+    return ModuleLoadResult();
   }
 };
 
diff --git a/include/clang/Frontend/CompilerInstance.h b/include/clang/Frontend/CompilerInstance.h
index 2f3dc3f808..2861511dd1 100644
--- a/include/clang/Frontend/CompilerInstance.h
+++ b/include/clang/Frontend/CompilerInstance.h
@@ -94,7 +94,7 @@ class CompilerInstance : public ModuleLoader {
 
   /// \brief The semantic analysis object.
   OwningPtr<Sema> TheSema;
-  
+
   /// \brief The frontend timer
   OwningPtr<llvm::Timer> FrontendTimer;
 
@@ -111,7 +111,7 @@ class CompilerInstance : public ModuleLoader {
   
   /// \brief The result of the last module import.
   ///
-  Module *LastModuleImportResult;
+  ModuleLoadResult LastModuleImportResult;
   
   /// \brief Holds information about the output file.
   ///
@@ -645,9 +645,10 @@ public:
 
   /// }
   
-  virtual Module *loadModule(SourceLocation ImportLoc, ModuleIdPath Path,
-                             Module::NameVisibilityKind Visibility,
-                             bool IsInclusionDirective);
+  virtual ModuleLoadResult loadModule(SourceLocation ImportLoc,
+                                      ModuleIdPath Path,
+                                      Module::NameVisibilityKind Visibility,
+                                      bool IsInclusionDirective);
 };
 
 } // end namespace clang
diff --git a/include/clang/Lex/ModuleLoader.h b/include/clang/Lex/ModuleLoader.h
index 36d03c0aa2..3a5f41d510 100644
--- a/include/clang/Lex/ModuleLoader.h
+++ b/include/clang/Lex/ModuleLoader.h
@@ -17,16 +17,37 @@
 #include "clang/Basic/Module.h"
 #include "clang/Basic/SourceLocation.h"
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/PointerIntPair.h"
 
 namespace clang {
 
 class IdentifierInfo;
-  
+class Module;
+
 /// \brief A sequence of identifier/location pairs used to describe a particular
 /// module or submodule, e.g., std.vector.
 typedef llvm::ArrayRef<std::pair<IdentifierInfo*, SourceLocation> > 
   ModuleIdPath;
-  
+
+/// \brief Describes the result of attempting to load a module.
+class ModuleLoadResult {
+  llvm::PointerIntPair<Module *, 1, bool> Storage;
+
+public:
+  ModuleLoadResult() : Storage() { }
+
+  ModuleLoadResult(Module *module, bool missingExpected)
+    : Storage(module, missingExpected) { }
+
+  operator Module *() const { return Storage.getPointer(); }
+
+  /// \brief Determines whether the module, which failed to load, was
+  /// actually a submodule that we expected to see (based on implying the
+  /// submodule from header structure), but didn't materialize in the actual
+  /// module.
+  bool isMissingExpected() const { return Storage.getInt(); }
+};
+
 /// \brief Abstract interface for a module loader.
 ///
 /// This abstract interface describes a module loader, which is responsible
@@ -55,9 +76,10 @@ public:
   ///
   /// \returns If successful, returns the loaded module. Otherwise, returns 
   /// NULL to indicate that the module could not be loaded.
-  virtual Module *loadModule(SourceLocation ImportLoc, ModuleIdPath Path,
-                             Module::NameVisibilityKind Visibility,
-                             bool IsInclusionDirective) = 0;
+  virtual ModuleLoadResult loadModule(SourceLocation ImportLoc,
+                                      ModuleIdPath Path,
+                                      Module::NameVisibilityKind Visibility,
+                                      bool IsInclusionDirective) = 0;
 };
   
 }
diff --git a/include/clang/Lex/PreprocessorOptions.h b/include/clang/Lex/PreprocessorOptions.h
index e5fe373793..857161ddc0 100644
--- a/include/clang/Lex/PreprocessorOptions.h
+++ b/include/clang/Lex/PreprocessorOptions.h
@@ -13,6 +13,7 @@
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/StringSet.h"
 #include <cassert>
 #include <string>
 #include <utility>
@@ -126,7 +127,29 @@ public:
   /// to do so (e.g., if on-demand module construction moves out-of-process),
   /// we can add a cc1-level option to do so.
   SmallVector<std::string, 2> ModuleBuildPath;
+
+  /// \brief Records the set of modules
+  class FailedModulesSet : public llvm::RefCountedBase<FailedModulesSet> {
+    llvm::StringSet<> Failed;
+
+  public:
+    bool hasAlreadyFailed(StringRef module) {
+      return Failed.count(module) > 0;
+    }
+
+    void addFailed(StringRef module) {
+      Failed.insert(module);
+    }
+  };
   
+  /// \brief The set of modules that failed to build.
+  ///
+  /// This pointer will be shared among all of the compiler instances created
+  /// to (re)build modules, so that once a module fails to build anywhere,
+  /// other instances will see that the module has failed and won't try to
+  /// build it again.
+  llvm::IntrusiveRefCntPtr<FailedModulesSet> FailedModules;
+
   typedef std::vector<std::pair<std::string, std::string> >::iterator
     remapped_file_iterator;
   typedef std::vector<std::pair<std::string, std::string> >::const_iterator