arphaman created this revision.
This patch adds an `external_source_symbol` attribute to Clang. This attribute
specifies that a declaration originates
from an external source and describes the nature of that source.
This attribute is useful for mixed-language projects or project that use
auto-generated code. For instance, Xcode can use this attribute to provide a
correct 'jump-to-definition' feature. For a concrete example, consider a
protocol that's defined in a Swift file:
@objc public protocol SwiftProtocol {
func method()
}
This protocol can be used from Objective-C code by including a header file that
was generated by the Swift compiler. The declarations in that header can use
the ``external_source_symbol`` attribute to make Clang aware of the fact that
``SwiftProtocol`` actually originates from a Swift module:
__attribute__((external_source_symbol(language=Swift,defined_in="module")))
@protocol SwiftProtocol
@required
- (void) method;
@end
Consequently, when 'jump-to-definition' is performed at a location that
references `SwiftProtocol`, Xcode can jump to the original definition in the
Swift source file rather than jumping to the Objective-C declaration in the
auto-generated header file.
his attribute uses custom parsing to specify a varying number of clauses such
as 'language', 'defined_in' or 'generated_declaration'. The 'language' clause
specifies the source language from which the declaration originates. The
'defined_in' clause specifies the name of the source container in which the
declaration was defined (the exact definition of source container is
language-specific, e.g. Swift's source containers are modules, so
``defined_in`` should specify the Swift module name). The
'generated_declaration' is a flag that specifies that whether this declaration
was automatically generated by some tool or not.
Repository:
rL LLVM
https://reviews.llvm.org/D29819
Files:
include/clang/Basic/Attr.td
include/clang/Basic/AttrDocs.td
include/clang/Basic/DiagnosticCommonKinds.td
include/clang/Basic/DiagnosticParseKinds.td
include/clang/Parse/Parser.h
lib/Parse/ParseDecl.cpp
lib/Parse/Parser.cpp
lib/Sema/SemaDeclAttr.cpp
test/Parser/attr-external-source-symbol-cxx11.cpp
test/Parser/attr-external-source-symbol.m
test/Sema/attr-external-source-symbol.c
Index: test/Sema/attr-external-source-symbol.c
===================================================================
--- /dev/null
+++ test/Sema/attr-external-source-symbol.c
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -fsyntax-only -fblocks -verify %s
+
+void f1() __attribute__((external_source_symbol(language=Swift, defined_in="module", generated_declaration)));
+
+void f2() __attribute__((external_source_symbol(generated_declaration)));
+
+void f3()
+__attribute__((external_source_symbol)); // expected-error {{'external_source_symbol' attribute takes at least 1 argument}}
+
+void f4() {
+ int (^block)(void) = ^ (void)
+ __attribute__((external_source_symbol(language=Swift))) { // expected-warning {{'external_source_symbol' attribute ignored}}
+ return 1;
+ };
+}
Index: test/Parser/attr-external-source-symbol.m
===================================================================
--- /dev/null
+++ test/Parser/attr-external-source-symbol.m
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+void function() __attribute__((external_source_symbol(language=Swift, defined_in="module", generated_declaration)));
+
+__attribute__((external_source_symbol(language=Swift, defined_in="module")))
+@interface I
+
+- (void)method __attribute__((external_source_symbol(defined_in= "module")));
+
+@end
+
+enum E {
+ CaseA __attribute__((external_source_symbol(generated_declaration))),
+ CaseB __attribute__((external_source_symbol(generated_declaration, language=Swift)))
+} __attribute__((external_source_symbol(language = Swift)));
+
+void f2()
+__attribute__((external_source_symbol())); // expected-error {{expected 'language', 'defined_in', or 'generated_declaration'}}
+void f3()
+__attribute__((external_source_symbol(invalid))); // expected-error {{expected 'language', 'defined_in', or 'generated_declaration'}}
+void f4()
+__attribute__((external_source_symbol(language))); // expected-error {{expected '=' after language}}
+void f5()
+__attribute__((external_source_symbol(language=))); // expected-error {{expected a source language , e.g., 'Swift'}}
+void f6()
+__attribute__((external_source_symbol(defined_in=20))); // expected-error {{expected string literal for source container name in 'external_source_symbol' attribute}}
Index: test/Parser/attr-external-source-symbol-cxx11.cpp
===================================================================
--- /dev/null
+++ test/Parser/attr-external-source-symbol-cxx11.cpp
@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
+
+[[gnu::external_source_symbol(language=Swift, defined_in="module")]]
+void function() { }
+
+// expected-no-diagnostics
Index: lib/Sema/SemaDeclAttr.cpp
===================================================================
--- lib/Sema/SemaDeclAttr.cpp
+++ lib/Sema/SemaDeclAttr.cpp
@@ -2409,6 +2409,29 @@
}
}
+static void handleExternalSourceSymbolAttr(Sema &S, Decl *D,
+ const AttributeList &Attr) {
+ if (!checkAttributeAtLeastNumArgs(S, Attr, 1))
+ return;
+
+ if (!isa<NamedDecl>(D)) {
+ S.Diag(Attr.getLoc(), diag::warn_attribute_ignored) << Attr.getName();
+ return;
+ }
+
+ IdentifierInfo *Language = nullptr;
+ if (const IdentifierLoc *LanguageIdent = Attr.getArgAsIdent(0))
+ Language = LanguageIdent->Ident;
+ StringRef DefinedIn;
+ if (const auto *SE = dyn_cast_or_null<StringLiteral>(Attr.getArgAsExpr(1)))
+ DefinedIn = SE->getString();
+ bool IsGeneratedDeclaration = Attr.getArgAsIdent(2);
+
+ D->addAttr(::new (S.Context) ExternalSourceSymbolAttr(
+ Attr.getRange(), S.Context, Language, DefinedIn, IsGeneratedDeclaration,
+ Attr.getAttributeSpellingListIndex()));
+}
+
template <class T>
static T *mergeVisibilityAttr(Sema &S, Decl *D, SourceRange range,
typename T::VisibilityType value,
@@ -5804,6 +5827,9 @@
case AttributeList::AT_ExtVectorType:
handleExtVectorTypeAttr(S, scope, D, Attr);
break;
+ case AttributeList::AT_ExternalSourceSymbol:
+ handleExternalSourceSymbolAttr(S, D, Attr);
+ break;
case AttributeList::AT_MinSize:
handleMinSizeAttr(S, D, Attr);
break;
Index: lib/Parse/Parser.cpp
===================================================================
--- lib/Parse/Parser.cpp
+++ lib/Parse/Parser.cpp
@@ -493,6 +493,8 @@
Ident_strict = nullptr;
Ident_replacement = nullptr;
+ Ident_language = Ident_defined_in = Ident_generated_declaration = nullptr;
+
Ident__except = nullptr;
Ident__exception_code = Ident__exception_info = nullptr;
Index: lib/Parse/ParseDecl.cpp
===================================================================
--- lib/Parse/ParseDecl.cpp
+++ lib/Parse/ParseDecl.cpp
@@ -356,6 +356,10 @@
ParseAvailabilityAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc, ScopeName,
ScopeLoc, Syntax);
return;
+ } else if (AttrKind == AttributeList::AT_ExternalSourceSymbol) {
+ ParseExternalSourceSymbolAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc,
+ ScopeName, ScopeLoc, Syntax);
+ return;
} else if (AttrKind == AttributeList::AT_ObjCBridgeRelated) {
ParseObjCBridgeRelatedAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc,
ScopeName, ScopeLoc, Syntax);
@@ -1064,6 +1068,98 @@
Syntax, StrictLoc, ReplacementExpr.get());
}
+/// \brief Parse the contents of the "external_source_symbol" attribute.
+///
+/// external-source-symbol-attribute:
+/// 'external_source_symbol' '(' keyword-arg-list ')'
+///
+/// keyword-arg-list:
+/// keyword-arg
+/// keyword-arg ',' keyword-arg-list
+///
+/// keyword-arg:
+/// 'language' '=' language
+/// 'defined_in' '=' <string>
+/// 'generated_declaration'
+void Parser::ParseExternalSourceSymbolAttribute(
+ IdentifierInfo &ExternalSourceSymbol, SourceLocation Loc,
+ ParsedAttributes &Attrs, SourceLocation *EndLoc, IdentifierInfo *ScopeName,
+ SourceLocation ScopeLoc, AttributeList::Syntax Syntax) {
+ // Opening '('.
+ BalancedDelimiterTracker T(*this, tok::l_paren);
+ if (T.consumeOpen()) {
+ Diag(Tok, diag::err_expected) << tok::l_paren;
+ return;
+ }
+
+ // Initialize the pointers for the keyword identifiers when required.
+ if (!Ident_language) {
+ Ident_language = PP.getIdentifierInfo("language");
+ Ident_defined_in = PP.getIdentifierInfo("defined_in");
+ Ident_generated_declaration = PP.getIdentifierInfo("generated_declaration");
+ }
+
+ IdentifierLoc *Language = nullptr;
+ ExprResult DefinedInExpr;
+ IdentifierLoc *GeneratedDeclaration = nullptr;
+
+ // Parse the language/defined_in/generated_declaration keywords
+ do {
+ if (Tok.isNot(tok::identifier)) {
+ Diag(Tok, diag::err_external_source_symbol_expected_keyword);
+ SkipUntil(tok::r_paren, StopAtSemi);
+ return;
+ }
+
+ IdentifierInfo *Keyword = Tok.getIdentifierInfo();
+ if (Keyword == Ident_generated_declaration) {
+ GeneratedDeclaration = ParseIdentifierLoc();
+ continue;
+ }
+
+ if (Keyword != Ident_language && Keyword != Ident_defined_in) {
+ Diag(Tok, diag::err_external_source_symbol_expected_keyword);
+ SkipUntil(tok::r_paren, StopAtSemi);
+ return;
+ }
+
+ ConsumeToken();
+ if (ExpectAndConsume(tok::equal, diag::err_expected_after,
+ Keyword->getName())) {
+ SkipUntil(tok::r_paren, StopAtSemi);
+ return;
+ }
+
+ if (Keyword == Ident_language) {
+ if (Tok.isNot(tok::identifier)) {
+ Diag(Tok, diag::err_external_source_symbol_expected_language);
+ SkipUntil(tok::r_paren, StopAtSemi);
+ return;
+ }
+ Language = ParseIdentifierLoc();
+ } else {
+ // Keyword must be 'Ident_defined_in'.
+ if (Tok.isNot(tok::string_literal)) {
+ Diag(Tok, diag::err_expected_string_literal)
+ << /*Source='external_source_symbol attribute'*/ 3;
+ SkipUntil(tok::r_paren, StopAtSemi);
+ return;
+ }
+ DefinedInExpr = ParseStringLiteralExpression();
+ }
+ } while (TryConsumeToken(tok::comma));
+
+ // Closing ')'.
+ if (T.consumeClose())
+ return;
+ if (EndLoc)
+ *EndLoc = T.getCloseLocation();
+
+ ArgsUnion Args[] = {Language, DefinedInExpr.get(), GeneratedDeclaration};
+ Attrs.addNew(&ExternalSourceSymbol, SourceRange(Loc, T.getCloseLocation()),
+ ScopeName, ScopeLoc, Args, llvm::array_lengthof(Args), Syntax);
+}
+
/// \brief Parse the contents of the "objc_bridge_related" attribute.
/// objc_bridge_related '(' related_class ',' opt-class_method ',' opt-instance_method ')'
/// related_class:
Index: include/clang/Parse/Parser.h
===================================================================
--- include/clang/Parse/Parser.h
+++ include/clang/Parse/Parser.h
@@ -142,6 +142,10 @@
/// \brief Identifier for "replacement".
IdentifierInfo *Ident_replacement;
+ /// Identifiers used by the 'external_source_symbol' attribute.
+ IdentifierInfo *Ident_language, *Ident_defined_in,
+ *Ident_generated_declaration;
+
/// C++0x contextual keywords.
mutable IdentifierInfo *Ident_final;
mutable IdentifierInfo *Ident_GNU_final;
@@ -2286,6 +2290,14 @@
Optional<AvailabilitySpec> ParseAvailabilitySpec();
ExprResult ParseAvailabilityCheckExpr(SourceLocation StartLoc);
+ void ParseExternalSourceSymbolAttribute(IdentifierInfo &ExternalSourceSymbol,
+ SourceLocation Loc,
+ ParsedAttributes &Attrs,
+ SourceLocation *EndLoc,
+ IdentifierInfo *ScopeName,
+ SourceLocation ScopeLoc,
+ AttributeList::Syntax Syntax);
+
void ParseObjCBridgeRelatedAttribute(IdentifierInfo &ObjCBridgeRelated,
SourceLocation ObjCBridgeRelatedLoc,
ParsedAttributes &attrs,
Index: include/clang/Basic/DiagnosticParseKinds.td
===================================================================
--- include/clang/Basic/DiagnosticParseKinds.td
+++ include/clang/Basic/DiagnosticParseKinds.td
@@ -856,6 +856,12 @@
def err_availability_query_repeated_star : Error<
"'*' query has already been specified">;
+// External source symbol attribute
+def err_external_source_symbol_expected_keyword : Error<
+ "expected 'language', 'defined_in', or 'generated_declaration'">;
+def err_external_source_symbol_expected_language : Error<
+ "expected a source language , e.g., 'Swift'">;
+
// Type safety attributes
def err_type_safety_unknown_flag : Error<
"invalid comparison flag %0; use 'layout_compatible' or 'must_be_null'">;
Index: include/clang/Basic/DiagnosticCommonKinds.td
===================================================================
--- include/clang/Basic/DiagnosticCommonKinds.td
+++ include/clang/Basic/DiagnosticCommonKinds.td
@@ -45,7 +45,8 @@
"must end with ':'">;
def err_expected_string_literal : Error<"expected string literal "
"%select{in %1|for diagnostic message in static_assert|"
- "for optional message in 'availability' attribute}0">;
+ "for optional message in 'availability' attribute|"
+ "for source container name in 'external_source_symbol' attribute}0">;
def err_invalid_string_udl : Error<
"string literal with user-defined suffix cannot be used here">;
def err_invalid_character_udl : Error<
Index: include/clang/Basic/AttrDocs.td
===================================================================
--- include/clang/Basic/AttrDocs.td
+++ include/clang/Basic/AttrDocs.td
@@ -960,6 +960,60 @@
}];
}
+def ExternalSourceSymbolDocs : Documentation {
+ let Category = DocCatFunction;
+ let Content = [{
+The ``external_source_symbol`` attribute specifies that a declaration originates
+from an external source and describes the nature of that source.
+
+The fact that Clang is capable of recognizing declarations that were defined
+externally can be used to provide better tooling support for mixed-language
+projects or projects that rely on auto-generated code. For instance, an IDE that
+uses Clang and that supports mixed-language projects can use this attribute to
+provide a correct 'jump-to-definition' feature. For a concrete example,
+consider a protocol that's defined in a Swift file:
+
+.. code-block:: swift
+
+ @objc public protocol SwiftProtocol {
+ func method()
+ }
+
+This protocol can be used from Objective-C code by including a header file that
+was generated by the Swift compiler. The declarations in that header can use
+the ``external_source_symbol`` attribute to make Clang aware of the fact
+that ``SwiftProtocol`` actually originates from a Swift module:
+
+.. code-block:: objc
+
+ __attribute__((external_source_symbol(language=Swift,defined_in="module")))
+ @protocol SwiftProtocol
+ @required
+ - (void) method;
+ @end
+
+Consequently, when 'jump-to-definition' is performed at a location that
+references ``SwiftProtocol``, the IDE can jump to the original definition in
+the Swift source file rather than jumping to the Objective-C declaration in the
+auto-generated header file.
+
+The ``external_source_symbol`` attribute is a comma-separated list that includes
+clauses that describe the origin and the nature of the particular declaration.
+Those clauses can be:
+
+language=\ *identifier*
+ The source language in which this declaration was defined.
+
+defined_in=\ *string-literal*
+ The name of the source container in which the declaration was defined. The
+ exact definition of source container is language-specific, e.g. Swift's
+ source containers are modules, so ``defined_in`` should specify the Swift
+ module name.
+
+generated_declaration
+ This declaration was automatically generated by some tool.
+ }];
+}
def RequireConstantInitDocs : Documentation {
let Category = DocCatVariable;
Index: include/clang/Basic/Attr.td
===================================================================
--- include/clang/Basic/Attr.td
+++ include/clang/Basic/Attr.td
@@ -527,6 +527,17 @@
let Documentation = [AvailabilityDocs];
}
+def ExternalSourceSymbol : InheritableAttr {
+ let Spellings = [GNU<"external_source_symbol">,
+ CXX11<"gnu", "external_source_symbol">];
+ let Args = [IdentifierArgument<"language", 1>,
+ StringArgument<"definedIn", 1>,
+ BoolArgument<"generatedDeclaration", 1>];
+ let HasCustomParsing = 1;
+// let Subjects = SubjectList<[Named]>;
+ let Documentation = [ExternalSourceSymbolDocs];
+}
+
def Blocks : InheritableAttr {
let Spellings = [GNU<"blocks">];
let Args = [EnumArgument<"Type", "BlockType", ["byref"], ["ByRef"]>];
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