[PATCH] D137650: [clangd] Implement hover for C++ string literals

[v1nh1shungry via Phabricator via cfe-commits]

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Show C++ string-literals' character's type and length in a hover card

Issue related: https://github.com/clangd/clangd/issues/1016


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D137650

Files:
  clang-tools-extra/clangd/Hover.cpp
  clang-tools-extra/clangd/unittests/HoverTests.cpp


Index: clang-tools-extra/clangd/unittests/HoverTests.cpp
===================================================================
--- clang-tools-extra/clangd/unittests/HoverTests.cpp
+++ clang-tools-extra/clangd/unittests/HoverTests.cpp
@@ -1300,7 +1300,6 @@
       "auto x = ^42.0i;",
       "auto x = ^42;",
       "auto x = ^nullptr;",
-      "auto x = ^\"asdf\";",
   };
 
   for (const auto &Test : Tests) {
@@ -1326,6 +1325,11 @@
          HI.Type = "char";
          HI.Value = "65 (0x41)";
        }},
+      {"auto s = ^[[\"Hello, world!\"]]; // string literal",
+       [](HoverInfo &HI) {
+         HI.Name = "String Literal";
+         HI.Type = "const char[14]";
+       }},
       {
           R"cpp(// Local variable
             int main() {
Index: clang-tools-extra/clangd/Hover.cpp
===================================================================
--- clang-tools-extra/clangd/Hover.cpp
+++ clang-tools-extra/clangd/Hover.cpp
@@ -777,6 +777,52 @@
   return HI;
 }
 
+llvm::Optional<HoverInfo>
+getStringLiteralHoverContents(const StringLiteral *SL,
+                              const LangOptions &LangOpts) {
+  HoverInfo HI;
+
+  // TODO: Show string literal's contents
+  HI.Name = "String Literal";
+
+  // In C++ string literals have `const` qualifier, but in C it don't.
+  std::string Qualifier;
+
+  std::string CharType;
+  // C++
+  // TODO: Support different C++ standards
+  if (LangOpts.CPlusPlus) {
+    Qualifier = "const ";
+    switch (SL->getKind()) {
+    case StringLiteral::Ordinary:
+      CharType = "char";
+      break;
+    case StringLiteral::Wide:
+      CharType = "wchar_t";
+      break;
+    case StringLiteral::UTF8:
+      CharType = "char8_t";
+      break;
+    case StringLiteral::UTF16:
+      CharType = "char16_t";
+      break;
+    case StringLiteral::UTF32:
+      CharType = "char32_t";
+      break;
+    }
+  } else {
+    // TODO: For other languages
+    return llvm::None;
+  }
+
+  HoverInfo::PrintedType Type;
+  Type.Type =
+      Qualifier + CharType + "[" + std::to_string(SL->getLength() + 1) + "]";
+  HI.Type = Type;
+
+  return HI;
+}
+
 bool isLiteral(const Expr *E) {
   // Unfortunately there's no common base Literal classes inherits from
   // (apart from Expr), therefore these exclusions.
@@ -806,8 +852,14 @@
                                            const SymbolIndex *Index) {
   // There's not much value in hovering over "42" and getting a hover card
   // saying "42 is an int", similar for other literals.
-  if (isLiteral(E))
+  if (isLiteral(E)) {
+    // Generate hover info for string literals showing
+    // its character's type and length
+    if (const StringLiteral *SL = dyn_cast<StringLiteral>(E)) {
+      return getStringLiteralHoverContents(SL, AST.getLangOpts());
+    }
     return llvm::None;
+  }
 
   HoverInfo HI;
   // For `this` expr we currently generate hover with pointee type.


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