Swift: append clang module names in trap keys

We have found out there can be separate declarations (`VarDecl` or
`AccessorDecl`) which are effectively the same (with equal mangled name)
but come from different clang modules. This is the case for example
for glibc constants like `L_SET` that appear in both `SwiftGlibc` and
`CDispatch`.

In this patch, we simply avoid full deduplication in that case by
appending the module name to the trap key for non-swift modules.

A more solid solution should be found in the future.

Author: redsun82

swift/extractor/visitors/DeclVisitor.cpp

@@ -295,19 +295,30 @@ std::string DeclVisitor::mangledName(const swift::ValueDecl& decl) {
   // ASTMangler::mangleAnyDecl crashes when called on `ModuleDecl`
   // TODO find a more unique string working also when different modules are compiled with the same
   // name
+  std::ostringstream ret;
   if (decl.getKind() == swift::DeclKind::Module) {
-    return static_cast<const swift::ModuleDecl&>(decl).getRealName().str().str();
+    ret << static_cast<const swift::ModuleDecl&>(decl).getRealName().str().str();
+  } else if (decl.getKind() == swift::DeclKind::TypeAlias) {
+    // In cases like this (when coming from PCM)
+    //  typealias CFXMLTree = CFTree
+    //  typealias CFXMLTreeRef = CFXMLTree
+    // mangleAnyDecl mangles both CFXMLTree and CFXMLTreeRef into 'So12CFXMLTreeRefa'
+    // which is not correct and causes inconsistencies. mangleEntity makes these two distinct
+    // prefix adds a couple of special symbols, we don't necessary need them
+    ret << mangler.mangleEntity(&decl);
+  } else {
+    // prefix adds a couple of special symbols, we don't necessary need them
+    ret << mangler.mangleAnyDecl(&decl, /* prefix = */ false);
   }
-  // In cases like this (when coming from PCM)
-  //  typealias CFXMLTree = CFTree
-  //  typealias CFXMLTreeRef = CFXMLTree
-  // mangleAnyDecl mangles both CFXMLTree and CFXMLTreeRef into 'So12CFXMLTreeRefa'
-  // which is not correct and causes inconsistencies. mangleEntity makes these two distinct
-  if (decl.getKind() == swift::DeclKind::TypeAlias) {
-    return mangler.mangleEntity(&decl);
+  // there can be separate declarations (`VarDecl` or `AccessorDecl`) which are effectively the same
+  // (with equal mangled name) but come from different clang modules. This is the case for example
+  // for glibc constants like `L_SET` that appear in both `SwiftGlibc` and `CDispatch`.
+  // For the moment, we sidestep the problem by making them separate entities in the DB
+  // TODO find a more solid solution
+  if (decl.getModuleContext()->isNonSwiftModule()) {
+    ret << '_' << decl.getModuleContext()->getRealName().str().str();
   }
-  // prefix adds a couple of special symbols, we don't necessary need them
-  return mangler.mangleAnyDecl(&decl, /* prefix = */ false);
+  return ret.str();
 }
 
 void DeclVisitor::fillAbstractFunctionDecl(const swift::AbstractFunctionDecl& decl,