[AST] Add mechanism to notify module loading to other clients

This patch adds an optional callback function member to the AST Context.
The callback gets invoked when a new module (or overlay module) gets
loaded.

This can be used for instance by other clients, such as lldb, to perform
actions when a module gets loaded, like showing progress to the end-user.

rdar://94165195

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>

Author: medismailben

include/swift/AST/ASTContext.h

@@ -223,11 +223,13 @@ class ASTContext final {
   ASTContext(const ASTContext&) = delete;
   void operator=(const ASTContext&) = delete;
 
-  ASTContext(LangOptions &langOpts, TypeCheckerOptions &typecheckOpts,
-             SILOptions &silOpts, SearchPathOptions &SearchPathOpts,
-             ClangImporterOptions &ClangImporterOpts,
-             symbolgraphgen::SymbolGraphOptions &SymbolGraphOpts,
-             SourceManager &SourceMgr, DiagnosticEngine &Diags);
+  ASTContext(
+      LangOptions &langOpts, TypeCheckerOptions &typecheckOpts,
+      SILOptions &silOpts, SearchPathOptions &SearchPathOpts,
+      ClangImporterOptions &ClangImporterOpts,
+      symbolgraphgen::SymbolGraphOptions &SymbolGraphOpts,
+      SourceManager &SourceMgr, DiagnosticEngine &Diags,
+      std::function<bool(llvm::StringRef, bool)> PreModuleImportCallback = {});
 
 public:
   // Members that should only be used by ASTContext.cpp.
@@ -238,11 +240,13 @@ class ASTContext final {
 
   void operator delete(void *Data) throw();
 
-  static ASTContext *get(LangOptions &langOpts, TypeCheckerOptions &typecheckOpts,
-                         SILOptions &silOpts, SearchPathOptions &SearchPathOpts,
-                         ClangImporterOptions &ClangImporterOpts,
-                         symbolgraphgen::SymbolGraphOptions &SymbolGraphOpts,
-                         SourceManager &SourceMgr, DiagnosticEngine &Diags);
+  static ASTContext *
+  get(LangOptions &langOpts, TypeCheckerOptions &typecheckOpts,
+      SILOptions &silOpts, SearchPathOptions &SearchPathOpts,
+      ClangImporterOptions &ClangImporterOpts,
+      symbolgraphgen::SymbolGraphOptions &SymbolGraphOpts,
+      SourceManager &SourceMgr, DiagnosticEngine &Diags,
+      std::function<bool(llvm::StringRef, bool)> PreModuleImportCallback = {});
   ~ASTContext();
 
   /// Optional table of counters to report, nullptr when not collecting.
@@ -374,6 +378,10 @@ class ASTContext final {
   llvm::BumpPtrAllocator &
   getAllocator(AllocationArena arena = AllocationArena::Permanent) const;
 
+  /// An optional generic callback function invoked prior to importing a module.
+  mutable std::function<bool(llvm::StringRef ModuleName, bool IsOverlay)>
+      PreModuleImportCallback;
+
 public:
   /// Allocate - Allocate memory from the ASTContext bump pointer.
   void *Allocate(unsigned long bytes, unsigned alignment,
@@ -1107,6 +1115,9 @@ class ASTContext final {
   /// If a module by this name has already been loaded, the existing module will
   /// be returned.
   ///
+  /// \param ModulePath The module's \c ImportPath which describes
+  /// the name of the module being loaded, possibly including submodules.
+
   /// \returns The requested module, or NULL if the module cannot be found.
   ModuleDecl *getModule(ImportPath::Module ModulePath);
 

lib/AST/ASTContext.cpp

@@ -42,8 +42,8 @@
 #include "swift/AST/PropertyWrappers.h"
 #include "swift/AST/ProtocolConformance.h"
 #include "swift/AST/RawComment.h"
-#include "swift/AST/SearchPathOptions.h"
 #include "swift/AST/SILLayout.h"
+#include "swift/AST/SearchPathOptions.h"
 #include "swift/AST/SemanticAttrs.h"
 #include "swift/AST/SourceFile.h"
 #include "swift/AST/SubstitutionMap.h"
@@ -65,6 +65,7 @@
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/FormatVariadic.h"
 #include <algorithm>
 #include <memory>
 
@@ -578,13 +579,14 @@ void ASTContext::operator delete(void *Data) throw() {
   AlignedFree(Data);
 }
 
-ASTContext *ASTContext::get(LangOptions &langOpts,
-                            TypeCheckerOptions &typecheckOpts, SILOptions &silOpts,
-                            SearchPathOptions &SearchPathOpts,
-                            ClangImporterOptions &ClangImporterOpts,
-                            symbolgraphgen::SymbolGraphOptions &SymbolGraphOpts,
-                            SourceManager &SourceMgr, DiagnosticEngine &Diags) {
-  // If more than two data structures are concatenated, then the aggregate
+ASTContext *ASTContext::get(
+    LangOptions &langOpts, TypeCheckerOptions &typecheckOpts,
+    SILOptions &silOpts, SearchPathOptions &SearchPathOpts,
+    ClangImporterOptions &ClangImporterOpts,
+    symbolgraphgen::SymbolGraphOptions &SymbolGraphOpts,
+    SourceManager &SourceMgr, DiagnosticEngine &Diags,
+    std::function<bool(llvm::StringRef, bool)> PreModuleImportCallback) {
+  // If more than two data structures are concatentated, then the aggregate
   // size math needs to become more complicated due to per-struct alignment
   // constraints.
   auto align = std::max(alignof(ASTContext), alignof(Implementation));
@@ -594,19 +596,22 @@ ASTContext *ASTContext::get(LangOptions &langOpts,
   impl = reinterpret_cast<void *>(
       llvm::alignAddr(impl, llvm::Align(alignof(Implementation))));
   new (impl) Implementation();
-  return new (mem)
-      ASTContext(langOpts, typecheckOpts, silOpts, SearchPathOpts,
-                 ClangImporterOpts, SymbolGraphOpts, SourceMgr, Diags);
-}
-
-ASTContext::ASTContext(LangOptions &langOpts, TypeCheckerOptions &typecheckOpts,
-                       SILOptions &silOpts, SearchPathOptions &SearchPathOpts,
-                       ClangImporterOptions &ClangImporterOpts,
-                       symbolgraphgen::SymbolGraphOptions &SymbolGraphOpts,
-                       SourceManager &SourceMgr, DiagnosticEngine &Diags)
+  return new (mem) ASTContext(langOpts, typecheckOpts, silOpts, SearchPathOpts,
+                              ClangImporterOpts, SymbolGraphOpts, SourceMgr,
+                              Diags, PreModuleImportCallback);
+}
+
+ASTContext::ASTContext(
+    LangOptions &langOpts, TypeCheckerOptions &typecheckOpts,
+    SILOptions &silOpts, SearchPathOptions &SearchPathOpts,
+    ClangImporterOptions &ClangImporterOpts,
+    symbolgraphgen::SymbolGraphOptions &SymbolGraphOpts,
+    SourceManager &SourceMgr, DiagnosticEngine &Diags,
+    std::function<bool(llvm::StringRef, bool)> PreModuleImportCallback)
     : LangOpts(langOpts), TypeCheckerOpts(typecheckOpts), SILOpts(silOpts),
       SearchPathOpts(SearchPathOpts), ClangImporterOpts(ClangImporterOpts),
       SymbolGraphOpts(SymbolGraphOpts), SourceMgr(SourceMgr), Diags(Diags),
+      PreModuleImportCallback(PreModuleImportCallback),
       evaluator(Diags, langOpts), TheBuiltinModule(createBuiltinModule(*this)),
       StdlibModuleName(getIdentifier(STDLIB_NAME)),
       SwiftShimsModuleName(getIdentifier(SWIFT_SHIMS_NAME)),
@@ -622,18 +627,18 @@ ASTContext::ASTContext(LangOptions &langOpts, TypeCheckerOptions &typecheckOpts,
     The##SHORT_ID##Type(new (*this, AllocationArena::Permanent) \
                           ID##Type(*this)),
 #include "swift/AST/TypeNodes.def"
-    TheIEEE32Type(new (*this, AllocationArena::Permanent)
-                    BuiltinFloatType(BuiltinFloatType::IEEE32,*this)),
-    TheIEEE64Type(new (*this, AllocationArena::Permanent)
-                    BuiltinFloatType(BuiltinFloatType::IEEE64,*this)),
-    TheIEEE16Type(new (*this, AllocationArena::Permanent)
-                    BuiltinFloatType(BuiltinFloatType::IEEE16,*this)),
-    TheIEEE80Type(new (*this, AllocationArena::Permanent)
-                    BuiltinFloatType(BuiltinFloatType::IEEE80,*this)),
-    TheIEEE128Type(new (*this, AllocationArena::Permanent)
-                    BuiltinFloatType(BuiltinFloatType::IEEE128, *this)),
-    ThePPC128Type(new (*this, AllocationArena::Permanent)
-                    BuiltinFloatType(BuiltinFloatType::PPC128, *this)) {
+      TheIEEE32Type(new (*this, AllocationArena::Permanent)
+                        BuiltinFloatType(BuiltinFloatType::IEEE32, *this)),
+      TheIEEE64Type(new (*this, AllocationArena::Permanent)
+                        BuiltinFloatType(BuiltinFloatType::IEEE64, *this)),
+      TheIEEE16Type(new (*this, AllocationArena::Permanent)
+                        BuiltinFloatType(BuiltinFloatType::IEEE16, *this)),
+      TheIEEE80Type(new (*this, AllocationArena::Permanent)
+                        BuiltinFloatType(BuiltinFloatType::IEEE80, *this)),
+      TheIEEE128Type(new (*this, AllocationArena::Permanent)
+                         BuiltinFloatType(BuiltinFloatType::IEEE128, *this)),
+      ThePPC128Type(new (*this, AllocationArena::Permanent)
+                        BuiltinFloatType(BuiltinFloatType::PPC128, *this)) {
 
   // Initialize all of the known identifiers.
 #define IDENTIFIER_WITH_NAME(Name, IdStr) Id_##Name = getIdentifier(IdStr);
@@ -2211,6 +2216,8 @@ ASTContext::getModule(ImportPath::Module ModulePath) {
     return M;
 
   auto moduleID = ModulePath[0];
+  if (PreModuleImportCallback)
+    PreModuleImportCallback(moduleID.Item.str(), false /*=IsOverlay*/);
   for (auto &importer : getImpl().ModuleLoaders) {
     if (ModuleDecl *M = importer->loadModule(moduleID.Loc, ModulePath)) {
       if (LangOpts.EnableModuleLoadingRemarks) {
@@ -2235,12 +2242,17 @@ ModuleDecl *ASTContext::getOverlayModule(const FileUnit *FU) {
       return Existing;
   }
 
+  if (PreModuleImportCallback) {
+    SmallString<16> path;
+    ModPath.getString(path);
+    if (!path.empty())
+      PreModuleImportCallback(path.str(), /*IsOverlay=*/true);
+  }
   for (auto &importer : getImpl().ModuleLoaders) {
     if (importer.get() == getClangModuleLoader())
       continue;
-    if (ModuleDecl *M = importer->loadModule(SourceLoc(), ModPath)) {
+    if (ModuleDecl *M = importer->loadModule(SourceLoc(), ModPath))
       return M;
-    }
   }
 
   return nullptr;