[Parse] Check the SourceFile for #if evaluation

Remove the `EvaluateConditionals` flags from the
parser, and instead query the source file.

This commit also changes ParserUnit such that it
doesn't evaluate #if conditions by default, as
none of its clients appear to require it. The
only client that wasn't explicitly disabling #if
evaluation and is processing the resulting AST is
swift-indent, so this commit also adds a test to
ensure it continues to work correctly with #if
decls.

Author: hamishknight

include/swift/Parse/Parser.h

@@ -177,6 +177,11 @@ class Parser {
   /// bodies.
   bool isDelayedParsingEnabled() const;
 
+  /// Whether to evaluate the conditions of #if decls, meaning that the bodies
+  /// of any active clauses are hoisted such that they become sibling nodes with
+  /// the #if decl.
+  bool shouldEvaluatePoundIfDecls() const;
+
   void setCodeCompletionCallbacks(CodeCompletionCallbacks *Callbacks) {
     CodeCompletion = Callbacks;
   }
@@ -213,13 +218,6 @@ class Parser {
   /// Always empty if !SF.shouldBuildSyntaxTree().
   ParsedTrivia TrailingTrivia;
 
-  /// Whether to evaluate the conditions of #if decls, meaning that the bodies
-  /// of any active clauses are hoisted such that they become sibling nodes with
-  /// the #if decl.
-  // FIXME: When condition evaluation moves to a later phase, remove this bit
-  // and adjust the client call 'performParseOnly'.
-  bool EvaluateConditionals;
-
   /// The receiver to collect all consumed tokens.
   ConsumeTokenReceiver *TokReceiver;
 
@@ -397,17 +395,14 @@ class Parser {
   Parser(unsigned BufferID, SourceFile &SF, DiagnosticEngine* LexerDiags,
          SILParserTUStateBase *SIL,
          PersistentParserState *PersistentState,
-         std::shared_ptr<SyntaxParseActions> SPActions = nullptr,
-         bool EvaluateConditionals = true);
+         std::shared_ptr<SyntaxParseActions> SPActions = nullptr);
   Parser(unsigned BufferID, SourceFile &SF, SILParserTUStateBase *SIL,
          PersistentParserState *PersistentState = nullptr,
-         std::shared_ptr<SyntaxParseActions> SPActions = nullptr,
-         bool EvaluateConditionals = true);
+         std::shared_ptr<SyntaxParseActions> SPActions = nullptr);
   Parser(std::unique_ptr<Lexer> Lex, SourceFile &SF,
          SILParserTUStateBase *SIL = nullptr,
          PersistentParserState *PersistentState = nullptr,
-         std::shared_ptr<SyntaxParseActions> SPActions = nullptr,
-         bool EvaluateConditionals = true);
+         std::shared_ptr<SyntaxParseActions> SPActions = nullptr);
   ~Parser();
 
   /// Returns true if the buffer being parsed is allowed to contain SIL.

include/swift/Subsystems.h

@@ -108,8 +108,7 @@ namespace swift {
   /// \param SF The file within the module being parsed.
   ///
   /// \param BufferID The buffer to parse from.
-  void parseIntoSourceFile(SourceFile &SF, unsigned BufferID,
-                           bool EvaluateConditionals = true);
+  void parseIntoSourceFile(SourceFile &SF, unsigned BufferID);
 
   /// Parse a source file's SIL declarations into a given SIL module.
   void parseSourceFileSIL(SourceFile &SF, SILParserState *sil);

lib/Frontend/Frontend.cpp

@@ -1147,7 +1147,7 @@ void CompilerInstance::performParseOnly(bool EvaluateConditionals,
         SourceFileKind::Library, SourceFile::ImplicitModuleImportKind::None,
         BufferID, parsingOpts);
 
-    parseIntoSourceFile(*NextInput, BufferID, EvaluateConditionals);
+    parseIntoSourceFile(*NextInput, BufferID);
   }
 
   // Now parse the main file.
@@ -1157,7 +1157,7 @@ void CompilerInstance::performParseOnly(bool EvaluateConditionals,
     MainFile.SyntaxParsingCache = Invocation.getMainFileSyntaxParsingCache();
     assert(MainBufferID == MainFile.getBufferID());
 
-    parseIntoSourceFile(MainFile, MainBufferID, EvaluateConditionals);
+    parseIntoSourceFile(MainFile, MainBufferID);
   }
 
   assert(Context->LoadedModules.size() == 1 &&

lib/Parse/ParseIfConfig.cpp

@@ -609,7 +609,7 @@ ParserResult<IfConfigDecl> Parser::parseIfConfig(
 
   bool shouldEvaluate =
       // Don't evaluate if it's in '-parse' mode, etc.
-      EvaluateConditionals &&
+      shouldEvaluatePoundIfDecls() &&
       // If it's in inactive #if ... #endif block, there's no point to do it.
       !getScopeInfo().isInactiveConfigBlock();
 

lib/Parse/Parser.cpp

@@ -362,16 +362,14 @@ static LexerMode sourceFileKindToLexerMode(SourceFileKind kind) {
 
 Parser::Parser(unsigned BufferID, SourceFile &SF, SILParserTUStateBase *SIL,
                PersistentParserState *PersistentState,
-               std::shared_ptr<SyntaxParseActions> SPActions,
-               bool EvaluateConditionals)
+               std::shared_ptr<SyntaxParseActions> SPActions)
     : Parser(BufferID, SF, &SF.getASTContext().Diags, SIL, PersistentState,
-             std::move(SPActions), EvaluateConditionals) {}
+             std::move(SPActions)) {}
 
 Parser::Parser(unsigned BufferID, SourceFile &SF, DiagnosticEngine* LexerDiags,
                SILParserTUStateBase *SIL,
                PersistentParserState *PersistentState,
-               std::shared_ptr<SyntaxParseActions> SPActions,
-               bool EvaluateConditionals)
+               std::shared_ptr<SyntaxParseActions> SPActions)
     : Parser(
           std::unique_ptr<Lexer>(new Lexer(
               SF.getASTContext().LangOpts, SF.getASTContext().SourceMgr,
@@ -386,8 +384,7 @@ Parser::Parser(unsigned BufferID, SourceFile &SF, DiagnosticEngine* LexerDiags,
               SF.shouldBuildSyntaxTree()
                   ? TriviaRetentionMode::WithTrivia
                   : TriviaRetentionMode::WithoutTrivia)),
-          SF, SIL, PersistentState, std::move(SPActions),
-          EvaluateConditionals) {}
+          SF, SIL, PersistentState, std::move(SPActions)) {}
 
 namespace {
 
@@ -507,8 +504,7 @@ class TokenRecorder: public ConsumeTokenReceiver {
 Parser::Parser(std::unique_ptr<Lexer> Lex, SourceFile &SF,
                SILParserTUStateBase *SIL,
                PersistentParserState *PersistentState,
-               std::shared_ptr<SyntaxParseActions> SPActions,
-               bool EvaluateConditionals)
+               std::shared_ptr<SyntaxParseActions> SPActions)
   : SourceMgr(SF.getASTContext().SourceMgr),
     Diags(SF.getASTContext().Diags),
     SF(SF),
@@ -517,7 +513,6 @@ Parser::Parser(std::unique_ptr<Lexer> Lex, SourceFile &SF,
     CurDeclContext(&SF),
     Context(SF.getASTContext()),
     CurrentTokenHash(SF.getInterfaceHashPtr()),
-    EvaluateConditionals(EvaluateConditionals),
     TokReceiver(SF.shouldCollectToken() ?
                 new TokenRecorder(SF, L->getBufferID()) :
                 new ConsumeTokenReceiver()),
@@ -551,6 +546,11 @@ bool Parser::isDelayedParsingEnabled() const {
   return SF.hasDelayedBodyParsing();
 }
 
+bool Parser::shouldEvaluatePoundIfDecls() const {
+  auto opts = SF.getParsingOptions();
+  return !opts.contains(SourceFile::ParsingFlags::DisablePoundIfEvaluation);
+}
+
 bool Parser::allowTopLevelCode() const {
   return SF.isScriptMode();
 }
@@ -1179,7 +1179,8 @@ struct ParserUnit::Implementation {
             *ModuleDecl::create(Ctx.getIdentifier(ModuleName), Ctx), SFKind,
             BufferID, SourceFile::ImplicitModuleImportKind::None,
             Opts.CollectParsedToken, Opts.BuildSyntaxTree,
-            SourceFile::ParsingFlags::DisableDelayedBodies)) {}
+            SourceFile::ParsingFlags::DisableDelayedBodies |
+                SourceFile::ParsingFlags::DisablePoundIfEvaluation)) {}
 
   ~Implementation() {
     // We need to delete the parser before the context so that it can finalize

lib/ParseSIL/ParseSIL.cpp

@@ -119,8 +119,7 @@ static void deletePersistentParserState(PersistentParserState *state) {
   delete state;
 }
 
-void swift::parseIntoSourceFile(SourceFile &SF, unsigned int BufferID,
-                                bool EvaluateConditionals) {
+void swift::parseIntoSourceFile(SourceFile &SF, unsigned int BufferID) {
   auto &ctx = SF.getASTContext();
   std::shared_ptr<SyntaxTreeCreator> STreeCreator;
   if (SF.shouldBuildSyntaxTree()) {
@@ -139,8 +138,7 @@ void swift::parseIntoSourceFile(SourceFile &SF, unsigned int BufferID,
 
   FrontendStatsTracer tracer(SF.getASTContext().Stats,
                              "Parsing");
-  Parser P(BufferID, SF, /*SIL*/ nullptr, state, STreeCreator,
-           EvaluateConditionals);
+  Parser P(BufferID, SF, /*SIL*/ nullptr, state, STreeCreator);
   PrettyStackTraceParser StackTrace(P);
 
   llvm::SaveAndRestore<NullablePtr<llvm::MD5>> S(P.CurrentTokenHash,

test/swift-indent/main.swift

@@ -34,3 +34,11 @@ break
            collatz(r)
     }
 }
+
+  #if true
+   func foo() -> Int {
+        0
+     }
+ #else
+   1
+     #endif

test/swift-indent/main.swift.indent2.response

@@ -34,3 +34,11 @@ func collatz(n: Int, m: String?) {
     collatz(r)
   }
 }
+
+#if true
+func foo() -> Int {
+  0
+}
+#else
+1
+#endif

test/swift-indent/main.swift.indentswitch.response

@@ -34,3 +34,11 @@ func collatz(n: Int, m: String?) {
         collatz(r)
     }
 }
+
+#if true
+func foo() -> Int {
+    0
+}
+#else
+1
+#endif

test/swift-indent/main.swift.lines.response

@@ -34,3 +34,11 @@ break
            collatz(r)
     }
 }
+
+  #if true
+   func foo() -> Int {
+        0
+     }
+ #else
+   1
+     #endif