[clang] Provide to PPCallbacks full expression range even in single file parse mode.

Restore the behavior existing prior to fe2eefc.
Make reporting of unevaluated directive source range more consistent and
with fewer assumptions. In case of a failed evaluation don't assume any
specific token and don't assume correct `PPValue` range tracking.

Author: vsapsai

clang/lib/Lex/PPExpressions.cpp

@@ -903,9 +903,8 @@ Preprocessor::EvaluateDirectiveExpression(IdentifierInfo *&IfNDefMacro,
   SourceLocation ExprStartLoc = SourceMgr.getExpansionLoc(Tok.getLocation());
   if (EvaluateValue(ResVal, Tok, DT, true, *this)) {
     // Parse error, skip the rest of the macro line.
-    SourceRange ConditionRange = ExprStartLoc;
     if (Tok.isNot(tok::eod))
-      ConditionRange = DiscardUntilEndOfDirective(Tok);
+      DiscardUntilEndOfDirective(Tok);
 
     // Restore 'DisableMacroExpansion'.
     DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
@@ -916,7 +915,7 @@ Preprocessor::EvaluateDirectiveExpression(IdentifierInfo *&IfNDefMacro,
     return {std::nullopt,
             false,
             DT.IncludedUndefinedIds,
-            {ExprStartLoc, ConditionRange.getEnd()}};
+            {ExprStartLoc, Tok.getLocation()}};
   }
 
   EvaluatedDefined = DT.State != DefinedTracker::Unknown;
@@ -948,8 +947,10 @@ Preprocessor::EvaluateDirectiveExpression(IdentifierInfo *&IfNDefMacro,
 
     // Restore 'DisableMacroExpansion'.
     DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
-    SourceRange ValRange = ResVal.getRange();
-    return {std::nullopt, false, DT.IncludedUndefinedIds, ValRange};
+    return {std::nullopt,
+            false,
+            DT.IncludedUndefinedIds,
+            {ExprStartLoc, Tok.getLocation()}};
   }
 
   if (CheckForEoD) {

clang/unittests/Lex/PPCallbacksTest.cpp

@@ -237,14 +237,13 @@ class PPCallbacksTest : public ::testing::Test {
   }
 
   std::vector<CondDirectiveCallbacks::Result>
-  DirectiveExprRange(StringRef SourceText) {
+  DirectiveExprRange(StringRef SourceText, PreprocessorOptions PPOpts = {}) {
     HeaderSearchOptions HSOpts;
     TrivialModuleLoader ModLoader;
     std::unique_ptr<llvm::MemoryBuffer> Buf =
         llvm::MemoryBuffer::getMemBuffer(SourceText);
     SourceMgr.setMainFileID(SourceMgr.createFileID(std::move(Buf)));
     HeaderSearch HeaderInfo(HSOpts, SourceMgr, Diags, LangOpts, Target.get());
-    PreprocessorOptions PPOpts;
     Preprocessor PP(PPOpts, Diags, LangOpts, SourceMgr, HeaderInfo, ModLoader,
                     /*IILookup=*/nullptr, /*OwnsHeaderSearch=*/false);
     PP.Initialize(*Target);
@@ -569,6 +568,24 @@ TEST_F(PPCallbacksTest, DirectiveExprRanges) {
       Lexer::getSourceText(CharSourceRange(Results8[0].ConditionRange, false),
                            SourceMgr, LangOpts),
       "__FILE__ > FLOOFY");
+
+  const char *MultiExprIf = "#if defined(FLOOFY) || defined(FLUZZY)\n#endif\n";
+  const auto &Results9 = DirectiveExprRange(MultiExprIf);
+  EXPECT_EQ(Results9.size(), 1U);
+  EXPECT_EQ(
+      Lexer::getSourceText(CharSourceRange(Results9[0].ConditionRange, false),
+                           SourceMgr, LangOpts),
+      "defined(FLOOFY) || defined(FLUZZY)");
+
+  PreprocessorOptions PPOptsSingleFileParse;
+  PPOptsSingleFileParse.SingleFileParseMode = true;
+  const auto &Results10 =
+      DirectiveExprRange(MultiExprIf, PPOptsSingleFileParse);
+  EXPECT_EQ(Results10.size(), 1U);
+  EXPECT_EQ(
+      Lexer::getSourceText(CharSourceRange(Results10[0].ConditionRange, false),
+                           SourceMgr, LangOpts),
+      "defined(FLOOFY) || defined(FLUZZY)");
 }
 
 } // namespace