[clang-tools-extra] 4b2cf98 - [clangd] Support type hints for `decltype(expr)`

[Nathan Ridge via cfe-commits]

Author: v1nh1shungry
Date: 2022-12-19T16:10:26-05:00
New Revision: 4b2cf982cc51b425b935842e64aa7ec645ad6807

URL: https://github.com/llvm/llvm-project/commit/4b2cf982cc51b425b935842e64aa7ec645ad6807
DIFF: https://github.com/llvm/llvm-project/commit/4b2cf982cc51b425b935842e64aa7ec645ad6807.diff

LOG: [clangd] Support type hints for `decltype(expr)`

Reviewed By: nridge

Differential Revision: https://reviews.llvm.org/D138300

Added: 
    

Modified: 
    clang-tools-extra/clangd/InlayHints.cpp
    clang-tools-extra/clangd/unittests/InlayHintTests.cpp

Removed: 
    


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diff  --git a/clang-tools-extra/clangd/InlayHints.cpp b/clang-tools-extra/clangd/InlayHints.cpp
index 07328b62e1fb3..6bbad09b9f7bd 100644
--- a/clang-tools-extra/clangd/InlayHints.cpp
+++ b/clang-tools-extra/clangd/InlayHints.cpp
@@ -218,6 +218,13 @@ class InlayHintVisitor : public RecursiveASTVisitor<InlayHintVisitor> {
     StructuredBindingPolicy.PrintCanonicalTypes = true;
   }
 
+  bool VisitTypeLoc(TypeLoc TL) {
+    if (const auto *DT = llvm::dyn_cast<DecltypeType>(TL.getType()))
+      if (QualType UT = DT->getUnderlyingType(); !UT->isDependentType())
+        addTypeHint(TL.getSourceRange(), UT, ": ");
+    return true;
+  }
+
   bool VisitCXXConstructExpr(CXXConstructExpr *E) {
     // Weed out constructor calls that don't look like a function call with
     // an argument list, by checking the validity of getParenOrBraceRange().

diff  --git a/clang-tools-extra/clangd/unittests/InlayHintTests.cpp b/clang-tools-extra/clangd/unittests/InlayHintTests.cpp
index 26e3936595db1..fa90abec02cbc 100644
--- a/clang-tools-extra/clangd/unittests/InlayHintTests.cpp
+++ b/clang-tools-extra/clangd/unittests/InlayHintTests.cpp
@@ -1361,6 +1361,29 @@ TEST(TypeHints, Aliased) {
   EXPECT_THAT(hintsOfKind(AST, InlayHintKind::Type), IsEmpty());
 }
 
+TEST(TypeHints, Decltype) {
+  assertTypeHints(R"cpp(
+    $a[[decltype(0)]] a;
+    // FIXME: will be nice to show `: int` instead
+    $b[[decltype(a)]] b;
+    const $c[[decltype(0)]] &c = b;
+
+    // Don't show for dependent type
+    template <class T>
+    constexpr decltype(T{}) d;
+
+    $e[[decltype(0)]] e();
+    auto f() -> $f[[decltype(0)]];
+
+    template <class, class> struct Foo;
+    using G = Foo<$g[[decltype(0)]], float>;
+  )cpp",
+                  ExpectedHint{": int", "a"},
+                  ExpectedHint{": decltype(0)", "b"},
+                  ExpectedHint{": int", "c"}, ExpectedHint{": int", "e"},
+                  ExpectedHint{": int", "f"}, ExpectedHint{": int", "g"});
+}
+
 TEST(DesignatorHints, Basic) {
   assertDesignatorHints(R"cpp(
     struct S { int x, y, z; };