PR17567: Improve diagnostic for a mistyped constructor name. If we see something

that looks like a function declaration, except that it's missing a return type,
try typo-correcting it to the relevant constructor name.

In passing, fix a bug where the missing-type-specifier recovery codepath would
drop a preceding scope specifier on the floor, leading to follow-on diagnostics
and incorrect recovery for the auto-in-c++98 hack.

llvm-svn: 192644

2 files changed, 58 insertions, 15 deletions

diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 31349ce9946..0f480c13353 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -2095,6 +2095,8 @@ bool Parser::ParseImplicitInt(DeclSpec &DS, CXXScopeSpec *SS,
       DS.getStorageClassSpec() == DeclSpec::SCS_auto) {
     // Don't require a type specifier if we have the 'auto' storage class
     // specifier in C++98 -- we'll promote it to a type specifier.
+    if (SS)
+      AnnotateScopeToken(*SS, /*IsNewAnnotation*/false);
     return false;
   }
 
@@ -2156,16 +2158,6 @@ bool Parser::ParseImplicitInt(DeclSpec &DS, CXXScopeSpec *SS,
     // Look ahead to the next token to try to figure out what this declaration
     // was supposed to be.
     switch (NextToken().getKind()) {
-    case tok::comma:
-    case tok::equal:
-    case tok::kw_asm:
-    case tok::l_brace:
-    case tok::l_square:
-    case tok::semi:
-      // This looks like a variable declaration. The type is probably missing.
-      // We're done parsing decl-specifiers.
-      return false;
-
     case tok::l_paren: {
       // static x(4); // 'x' is not a type
       // x(int n);    // 'x' is not a type
@@ -2178,12 +2170,37 @@ bool Parser::ParseImplicitInt(DeclSpec &DS, CXXScopeSpec *SS,
       ConsumeToken();
       TPResult TPR = TryParseDeclarator(/*mayBeAbstract*/false);
       PA.Revert();
-      if (TPR == TPResult::False())
-        return false;
-      // The identifier is followed by a parenthesized declarator.
-      // It's supposed to be a type.
-      break;
+
+      if (TPR != TPResult::False()) {
+        // The identifier is followed by a parenthesized declarator.
+        // It's supposed to be a type.
+        break;
+      }
+
+      // If we're in a context where we could be declaring a constructor,
+      // check whether this is a constructor declaration with a bogus name.
+      if (DSC == DSC_class || (DSC == DSC_top_level && SS)) {
+        IdentifierInfo *II = Tok.getIdentifierInfo();
+        if (Actions.isCurrentClassNameTypo(II, SS)) {
+          Diag(Loc, diag::err_constructor_bad_name)
+            << Tok.getIdentifierInfo() << II
+            << FixItHint::CreateReplacement(Tok.getLocation(), II->getName());
+          Tok.setIdentifierInfo(II);
+        }
+      }
+      // Fall through.
     }
+    case tok::comma:
+    case tok::equal:
+    case tok::kw_asm:
+    case tok::l_brace:
+    case tok::l_square:
+    case tok::semi:
+      // This looks like a variable or function declaration. The type is
+      // probably missing. We're done parsing decl-specifiers.
+      if (SS)
+        AnnotateScopeToken(*SS, /*IsNewAnnotation*/false);
+      return false;
 
     default:
       // This is probably supposed to be a type. This includes cases like:
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 6ec344d1e3c..655c9e2c3d0 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -1227,6 +1227,32 @@ bool Sema::isCurrentClassName(const IdentifierInfo &II, Scope *,
   return false;
 }
 
+/// \brief Determine whether the identifier II is a typo for the name of
+/// the class type currently being defined. If so, update it to the identifier
+/// that should have been used.
+bool Sema::isCurrentClassNameTypo(IdentifierInfo *&II, const CXXScopeSpec *SS) {
+  assert(getLangOpts().CPlusPlus && "No class names in C!");
+
+  if (!getLangOpts().SpellChecking)
+    return false;
+
+  CXXRecordDecl *CurDecl;
+  if (SS && SS->isSet() && !SS->isInvalid()) {
+    DeclContext *DC = computeDeclContext(*SS, true);
+    CurDecl = dyn_cast_or_null<CXXRecordDecl>(DC);
+  } else
+    CurDecl = dyn_cast_or_null<CXXRecordDecl>(CurContext);
+
+  if (CurDecl && CurDecl->getIdentifier() && II != CurDecl->getIdentifier() &&
+      3 * II->getName().edit_distance(CurDecl->getIdentifier()->getName())
+          < II->getLength()) {
+    II = CurDecl->getIdentifier();
+    return true;
+  }
+
+  return false;
+}
+
 /// \brief Determine whether the given class is a base class of the given
 /// class, including looking at dependent bases.
 static bool findCircularInheritance(const CXXRecordDecl *Class,