Add descriptions to completed expressions

Summary:
Completing inside the expression command now uses the new description API
to also provide additional information to the user. For now this information
are the types of variables/fields and the signatures of completed function calls.

Reviewers: #lldb, JDevlieghere

Reviewed By: JDevlieghere

Subscribers: JDevlieghere, lldb-commits

Differential Revision: https://reviews.llvm.org/D52103

llvm-svn: 342385

1 files changed, 32 insertions, 8 deletions

diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
index b905b9a1d57d..ccdff214f25b 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
@@ -14,6 +14,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/ASTDiagnostic.h"
 #include "clang/AST/ExternalASTSource.h"
+#include "clang/AST/PrettyPrinter.h"
 #include "clang/Basic/DiagnosticIDs.h"
 #include "clang/Basic/FileManager.h"
 #include "clang/Basic/SourceLocation.h"
@@ -564,6 +565,9 @@ class CodeComplete : public CodeCompleteConsumer {
   std::string m_expr;
   unsigned m_position = 0;
   CompletionRequest &m_request;
+  /// The printing policy we use when printing declarations for our completion
+  /// descriptions.
+  clang::PrintingPolicy m_desc_policy;
 
   /// Returns true if the given character can be used in an identifier.
   /// This also returns true for numbers because for completion we usually
@@ -638,10 +642,22 @@ public:
   /// @param[out] position
   ///    The character position of the user cursor in the `expr` parameter.
   ///
-  CodeComplete(CompletionRequest &request, std::string expr, unsigned position)
+  CodeComplete(CompletionRequest &request, clang::LangOptions ops,
+               std::string expr, unsigned position)
       : CodeCompleteConsumer(CodeCompleteOptions(), false),
         m_info(std::make_shared<GlobalCodeCompletionAllocator>()), m_expr(expr),
-        m_position(position), m_request(request) {}
+        m_position(position), m_request(request), m_desc_policy(ops) {
+
+    // Ensure that the printing policy is producing a description that is as
+    // short as possible.
+    m_desc_policy.SuppressScope = true;
+    m_desc_policy.SuppressTagKeyword = true;
+    m_desc_policy.FullyQualifiedName = false;
+    m_desc_policy.TerseOutput = true;
+    m_desc_policy.IncludeNewlines = false;
+    m_desc_policy.UseVoidForZeroParams = false;
+    m_desc_policy.Bool = true;
+  }
 
   /// Deregisters and destroys this code-completion consumer.
   virtual ~CodeComplete() {}
@@ -692,6 +708,7 @@ public:
 
       CodeCompletionResult &R = Results[I];
       std::string ToInsert;
+      std::string Description;
       // Handle the different completion kinds that come from the Sema.
       switch (R.Kind) {
       case CodeCompletionResult::RK_Declaration: {
@@ -705,10 +722,16 @@ public:
             ToInsert += "()";
           else
             ToInsert += "(";
-        }
-        // If we try to complete a namespace, then we can directly append
-        // the '::'.
-        if (const NamespaceDecl *N = dyn_cast<NamespaceDecl>(D)) {
+          raw_string_ostream OS(Description);
+          F->print(OS, m_desc_policy, false);
+          OS.flush();
+        } else if (const VarDecl *V = dyn_cast<VarDecl>(D)) {
+          Description = V->getType().getAsString(m_desc_policy);
+        } else if (const FieldDecl *F = dyn_cast<FieldDecl>(D)) {
+          Description = F->getType().getAsString(m_desc_policy);
+        } else if (const NamespaceDecl *N = dyn_cast<NamespaceDecl>(D)) {
+          // If we try to complete a namespace, then we can directly append
+          // the '::'.
           if (!N->isAnonymousNamespace())
             ToInsert += "::";
         }
@@ -735,7 +758,7 @@ public:
         // with the kind of result the lldb API expects.
         std::string CompletionSuggestion =
             mergeCompletion(m_expr, m_position, ToInsert);
-        m_request.AddCompletion(CompletionSuggestion);
+        m_request.AddCompletion(CompletionSuggestion, Description);
       }
     }
   }
@@ -773,7 +796,8 @@ bool ClangExpressionParser::Complete(CompletionRequest &request, unsigned line,
   // the LLVMUserExpression which exposes the right API. This should never fail
   // as we always have a ClangUserExpression whenever we call this.
   LLVMUserExpression &llvm_expr = *static_cast<LLVMUserExpression *>(&m_expr);
-  CodeComplete CC(request, llvm_expr.GetUserText(), typed_pos);
+  CodeComplete CC(request, m_compiler->getLangOpts(), llvm_expr.GetUserText(),
+                  typed_pos);
   // We don't need a code generator for parsing.
   m_code_generator.reset();
   // Start parsing the expression with our custom code completion consumer.