Add support for editor placeholders to Clang

This commit teaches Clang to recognize editor placeholders that are produced
when an IDE like Xcode inserts a code-completion result that includes a
placeholder. Now when the lexer sees a placeholder token, it emits an
'editor placeholder in source file' error and creates an identifier token
that represents the placeholder. The parser/sema can now recognize the
placeholders and can suppress the diagnostics related to the placeholders. This
ensures that live issues in an IDE like Xcode won't get spurious diagnostics
related to placeholders.

This commit also adds a new compiler option named '-fallow-editor-placeholders'
that silences the 'editor placeholder in source file' error. This is useful
for an IDE like Xcode as we don't want to display those errors in live issues.

rdar://31581400

Differential Revision: https://reviews.llvm.org/D32081

llvm-svn: 300667

diff --git a/clang/include/clang/Basic/DiagnosticLexKinds.td b/clang/include/clang/Basic/DiagnosticLexKinds.td
index b5b5acb..cf33d5f 100644 (file)
--- a/clang/include/clang/Basic/DiagnosticLexKinds.td
+++ b/clang/include/clang/Basic/DiagnosticLexKinds.td
@@ -242,6 +242,7 @@ def warn_bad_character_encoding : ExtWarn<
   "illegal character encoding in character literal">,
   InGroup<InvalidSourceEncoding>;
 def err_lexing_string : Error<"failure when lexing a string">;
+def err_placeholder_in_source : Error<"editor placeholder in source file">;
 
 
 //===----------------------------------------------------------------------===//

diff --git a/clang/include/clang/Basic/IdentifierTable.h b/clang/include/clang/Basic/IdentifierTable.h
index a5fd141..9b1ba4a 100644 (file)
--- a/clang/include/clang/Basic/IdentifierTable.h
+++ b/clang/include/clang/Basic/IdentifierTable.h
@@ -355,6 +355,19 @@ public:
       RecomputeNeedsHandleIdentifier();
   }
 
+  /// Return true if this identifier is an editor placeholder.
+  ///
+  /// Editor placeholders are produced by the code-completion engine and are
+  /// represented as characters between '<#' and '#>' in the source code. An
+  /// example of auto-completed call with a placeholder parameter is shown
+  /// below:
+  /// \code
+  ///   function(<#int x#>);
+  /// \endcode
+  bool isEditorPlaceholder() const {
+    return getName().startswith("<#") && getName().endswith("#>");
+  }
+
   /// \brief Provide less than operator for lexicographical sorting.
   bool operator<(const IdentifierInfo &RHS) const {
     return getName() < RHS.getName();

diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
index c8e1972..6ae34a8 100644 (file)
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -266,6 +266,8 @@ LANGOPT(SanitizeAddressFieldPadding, 2, 0, "controls how aggressive is ASan "
 
 LANGOPT(XRayInstrument, 1, 0, "controls whether to do XRay instrumentation")
 
+LANGOPT(AllowEditorPlaceholders, 1, 0, "allow editor placeholders in source")
+
 #undef LANGOPT
 #undef COMPATIBLE_LANGOPT
 #undef BENIGN_LANGOPT

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index c6c9d5d..6f1ccfb 100644 (file)
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -1487,6 +1487,12 @@ def fstrict_return : Flag<["-"], "fstrict-return">, Group<f_Group>,
 def fno_strict_return : Flag<["-"], "fno-strict-return">, Group<f_Group>,
   Flags<[CC1Option]>;
 
+def fallow_editor_placeholders : Flag<["-"], "fallow-editor-placeholders">,
+  Group<f_Group>, Flags<[CC1Option]>,
+  HelpText<"Treat editor placeholders as valid source code">;
+def fno_allow_editor_placeholders : Flag<["-"],
+  "fno-allow-editor-placeholders">, Group<f_Group>;
+
 def fdebug_types_section: Flag <["-"], "fdebug-types-section">, Group<f_Group>,
   Flags<[CC1Option]>, HelpText<"Place debug types in their own section (ELF Only)">;
 def fno_debug_types_section: Flag<["-"], "fno-debug-types-section">, Group<f_Group>,

diff --git a/clang/include/clang/Lex/Lexer.h b/clang/include/clang/Lex/Lexer.h
index 830c25a..6ac6316 100644 (file)
--- a/clang/include/clang/Lex/Lexer.h
+++ b/clang/include/clang/Lex/Lexer.h
@@ -638,6 +638,8 @@ private:
   bool IsStartOfConflictMarker(const char *CurPtr);
   bool HandleEndOfConflictMarker(const char *CurPtr);
 
+  bool lexEditorPlaceholder(Token &Result, const char *CurPtr);
+
   bool isCodeCompletionPoint(const char *CurPtr) const;
   void cutOffLexing() { BufferPtr = BufferEnd; }
 

diff --git a/clang/include/clang/Lex/Token.h b/clang/include/clang/Lex/Token.h
index 4393e20..02a1fef 100644 (file)
--- a/clang/include/clang/Lex/Token.h
+++ b/clang/include/clang/Lex/Token.h
@@ -84,6 +84,7 @@ public:
     StringifiedInMacro = 0x100, // This string or character literal is formed by
                                 // macro stringizing or charizing operator.
     CommaAfterElided = 0x200, // The comma following this token was elided (MS).
+    IsEditorPlaceholder = 0x400, // This identifier is a placeholder.
   };
 
   tok::TokenKind getKind() const { return Kind; }
@@ -298,6 +299,13 @@ public:
 
   /// Returns true if the comma after this token was elided.
   bool commaAfterElided() const { return getFlag(CommaAfterElided); }
+
+  /// Returns true if this token is an editor placeholder.
+  ///
+  /// Editor placeholders are produced by the code-completion engine and are
+  /// represented as characters between '<#' and '#>' in the source code. The
+  /// lexer uses identifier tokens to represent placeholders.
+  bool isEditorPlaceholder() const { return getFlag(IsEditorPlaceholder); }
 };
 
 /// \brief Information about the conditional stack (\#if directives)

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index b6887b8..49708e7 100644 (file)
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2306,6 +2306,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   if (!Args.hasFlag(options::OPT_fstrict_return, options::OPT_fno_strict_return,
                     true))
     CmdArgs.push_back("-fno-strict-return");
+  if (Args.hasFlag(options::OPT_fallow_editor_placeholders,
+                   options::OPT_fno_allow_editor_placeholders, false))
+    CmdArgs.push_back("-fallow-editor-placeholders");
   if (Args.hasFlag(options::OPT_fstrict_vtable_pointers,
                    options::OPT_fno_strict_vtable_pointers,
                    false))

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 05db457..0e0eb40 100644 (file)
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2322,6 +2322,9 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
       Args.getAllArgValues(OPT_fxray_always_instrument);
   Opts.XRayNeverInstrumentFiles =
       Args.getAllArgValues(OPT_fxray_never_instrument);
+
+  // -fallow-editor-placeholders
+  Opts.AllowEditorPlaceholders = Args.hasArg(OPT_fallow_editor_placeholders);
 }
 
 static void ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,

diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index dc911ef..003c9b5 100644 (file)
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -2716,6 +2716,37 @@ bool Lexer::HandleEndOfConflictMarker(const char *CurPtr) {
   return false;
 }
 
+static const char *findPlaceholderEnd(const char *CurPtr,
+                                      const char *BufferEnd) {
+  if (CurPtr == BufferEnd)
+    return nullptr;
+  BufferEnd -= 1; // Scan until the second last character.
+  for (; CurPtr != BufferEnd; ++CurPtr) {
+    if (CurPtr[0] == '#' && CurPtr[1] == '>')
+      return CurPtr + 2;
+  }
+  return nullptr;
+}
+
+bool Lexer::lexEditorPlaceholder(Token &Result, const char *CurPtr) {
+  assert(CurPtr[-1] == '<' && CurPtr[0] == '#' && "Not a placeholder!");
+  if (!PP || LexingRawMode)
+    return false;
+  const char *End = findPlaceholderEnd(CurPtr + 1, BufferEnd);
+  if (!End)
+    return false;
+  const char *Start = CurPtr - 1;
+  if (!LangOpts.AllowEditorPlaceholders)
+    Diag(Start, diag::err_placeholder_in_source);
+  Result.startToken();
+  FormTokenWithChars(Result, End, tok::raw_identifier);
+  Result.setRawIdentifierData(Start);
+  PP->LookUpIdentifierInfo(Result);
+  Result.setFlag(Token::IsEditorPlaceholder);
+  BufferPtr = End;
+  return true;
+}
+
 bool Lexer::isCodeCompletionPoint(const char *CurPtr) const {
   if (PP && PP->isCodeCompletionEnabled()) {
     SourceLocation Loc = FileLoc.getLocWithOffset(CurPtr-BufferStart);
@@ -3473,6 +3504,8 @@ LexNextToken:
     } else if (LangOpts.Digraphs && Char == '%') {     // '<%' -> '{'
       CurPtr = ConsumeChar(CurPtr, SizeTmp, Result);
       Kind = tok::l_brace;
+    } else if (Char == '#' && lexEditorPlaceholder(Result, CurPtr)) {
+      return true;
     } else {
       Kind = tok::less;
     }

diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index 265c12d..edbfc63 100644 (file)
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -851,6 +851,10 @@ Parser::ParseExternalDeclaration(ParsedAttributesWithRange &attrs,
 
   default:
   dont_know:
+    if (Tok.isEditorPlaceholder()) {
+      ConsumeToken();
+      return nullptr;
+    }
     // We can't tell whether this is a function-definition or declaration yet.
     return ParseDeclarationOrFunctionDefinition(attrs, DS);
   }
@@ -1679,6 +1683,8 @@ bool Parser::TryAnnotateTypeOrScopeToken() {
           return false;
         }
       }
+      if (Tok.isEditorPlaceholder())
+        return true;
 
       Diag(Tok.getLocation(), diag::err_expected_qualified_after_typename);
       return true;

diff --git a/clang/lib/Sema/SemaCXXScopeSpec.cpp b/clang/lib/Sema/SemaCXXScopeSpec.cpp
index 57471de..6da4d2a 100644 (file)
--- a/clang/lib/Sema/SemaCXXScopeSpec.cpp
+++ b/clang/lib/Sema/SemaCXXScopeSpec.cpp
@@ -480,6 +480,8 @@ bool Sema::BuildCXXNestedNameSpecifier(Scope *S, NestedNameSpecInfo &IdInfo,
                                        bool ErrorRecoveryLookup,
                                        bool *IsCorrectedToColon,
                                        bool OnlyNamespace) {
+  if (IdInfo.Identifier->isEditorPlaceholder())
+    return true;
   LookupResult Found(*this, IdInfo.Identifier, IdInfo.IdentifierLoc,
                      OnlyNamespace ? LookupNamespaceName
                                    : LookupNestedNameSpecifierName);

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 075e87b..f3ffcf5 100644 (file)
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -628,6 +628,9 @@ void Sema::DiagnoseUnknownTypeName(IdentifierInfo *&II,
                                    CXXScopeSpec *SS,
                                    ParsedType &SuggestedType,
                                    bool AllowClassTemplates) {
+  // Don't report typename errors for editor placeholders.
+  if (II->isEditorPlaceholder())
+    return;
   // We don't have anything to suggest (yet).
   SuggestedType = nullptr;
 

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index bb17452..5a56f70 100644 (file)
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -2129,6 +2129,12 @@ Sema::ActOnIdExpression(Scope *S, CXXScopeSpec &SS,
   IdentifierInfo *II = Name.getAsIdentifierInfo();
   SourceLocation NameLoc = NameInfo.getLoc();
 
+  if (II && II->isEditorPlaceholder()) {
+    // FIXME: When typed placeholders are supported we can create a typed
+    // placeholder expression node.
+    return ExprError();
+  }
+
   // C++ [temp.dep.expr]p3:
   //   An id-expression is type-dependent if it contains:
   //     -- an identifier that was declared with a dependent type,

diff --git a/clang/test/Driver/clang_f_opts.c b/clang/test/Driver/clang_f_opts.c
index 15c1eac..c54c618 100644 (file)
--- a/clang/test/Driver/clang_f_opts.c
+++ b/clang/test/Driver/clang_f_opts.c
@@ -494,3 +494,8 @@
 // RUN: %clang -### -S -fdebug-info-for-profiling -fno-debug-info-for-profiling %s 2>&1 | FileCheck -check-prefix=CHECK-NO-PROFILE-DEBUG %s
 // CHECK-PROFILE-DEBUG: -fdebug-info-for-profiling
 // CHECK-NO-PROFILE-DEBUG-NOT: -fdebug-info-for-profiling
+
+// RUN: %clang -### -S -fallow-editor-placeholders %s 2>&1 | FileCheck -check-prefix=CHECK-ALLOW-PLACEHOLDERS %s
+// RUN: %clang -### -S -fno-allow-editor-placeholders %s 2>&1 | FileCheck -check-prefix=CHECK-NO-ALLOW-PLACEHOLDERS %s
+// CHECK-ALLOW-PLACEHOLDERS: -fallow-editor-placeholders
+// CHECK-NO-ALLOW-PLACEHOLDERS-NOT: -fallow-editor-placeholders

diff --git a/clang/test/Parser/editor-placeholder-recovery.cpp b/clang/test/Parser/editor-placeholder-recovery.cpp
new file mode 100644 (file)
index 0000000..48c290e
--- /dev/null
+++ b/clang/test/Parser/editor-placeholder-recovery.cpp
@@ -0,0 +1,71 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c++11 -verify %s
+// RUN: %clang_cc1 -fsyntax-only -std=c++11 -fallow-editor-placeholders -DSUPPRESS -verify %s
+
+struct Struct {
+public:
+    void method(Struct &x);
+};
+
+struct <#struct name#> {
+  int <#field-name#>;
+#ifndef SUPPRESS
+  // expected-error@-3 {{editor placeholder in source file}}
+  // expected-error@-3 {{editor placeholder in source file}}
+#endif
+};
+
+typename <#typename#>::<#name#>;
+decltype(<#expression#>) foobar;
+typedef <#type#> <#name#>;
+#ifndef SUPPRESS
+  // expected-error@-4 2 {{editor placeholder in source file}}
+  // expected-error@-4 {{editor placeholder in source file}}
+  // expected-error@-4 2 {{editor placeholder in source file}}
+#endif
+
+namespace <#identifier#> {
+  <#declarations#>
+#ifndef SUPPRESS
+  // expected-error@-3 {{editor placeholder in source file}}
+  // expected-error@-3 {{editor placeholder in source file}}
+#endif
+
+}
+
+using <#qualifier#>::<#name#>;
+#ifndef SUPPRESS
+  // expected-error@-2 2 {{editor placeholder in source file}}
+#endif
+
+void avoidPlaceholderErrors(Struct &obj) {
+    static_cast< <#type#> >(<#expression#>);
+    while (<#condition#>) {
+        <#statements#>
+    }
+    obj.method(<#Struct &x#>);
+#ifndef SUPPRESS
+  // expected-error@-6 2 {{editor placeholder in source file}}
+  // expected-error@-6 {{editor placeholder in source file}}
+  // expected-error@-6 {{editor placeholder in source file}}
+  // expected-error@-5 {{editor placeholder in source file}}
+#endif
+    switch (<#expression#>) {
+        case <#constant#>:
+            <#statements#>
+#ifndef SUPPRESS
+  // expected-error@-4 {{editor placeholder in source file}}
+  // expected-error@-4 {{editor placeholder in source file}}
+  // expected-error@-4 {{editor placeholder in source file}}
+#endif
+            break;
+
+        default:
+            break;
+    }
+}
+
+void Struct::method(<#Struct &x#>, noSupressionHere) { // expected-error {{unknown type name 'noSupressionHere'}} expected-error {{C++ requires a type specifier for all declarations}}
+#ifndef SUPPRESS
+  // expected-error@-2 {{editor placeholder in source file}}
+#endif
+}

diff --git a/clang/test/Parser/placeholder-recovery.m b/clang/test/Parser/placeholder-recovery.m
index b43b0e4..4f22ea7 100644 (file)
--- a/clang/test/Parser/placeholder-recovery.m
+++ b/clang/test/Parser/placeholder-recovery.m
@@ -1,11 +1,14 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s
 
+@protocol NSObject
+@end
+
+@protocol <#protocol name#> <NSObject> // expected-error {{editor placeholder in source file}}
+// expected-note@-1 {{protocol started here}}
+
 // FIXME: We could do much better with this, if we recognized
 // placeholders somehow. However, we're content with not generating
 // bogus 'archaic' warnings with bad location info.
-@protocol <#protocol name#> <NSObject> // expected-error {{expected identifier or '('}} \
-// expected-error 2{{expected identifier}} \
-// expected-warning{{protocol has no object type specified; defaults to qualified 'id'}}
-<#methods#>
+<#methods#> // expected-error {{editor placeholder in source file}}
 
-@end
+@end // expected-error {{prefix attribute must be followed by an interface or protocol}} expected-error {{missing '@end'}}