[clang] 761f3d1 - [clang][PreProcessor] Cutoff parsing after hitting completion point

[Kadir Cetinkaya via cfe-commits]

Author: Kadir Cetinkaya
Date: 2021-05-10T11:24:27+02:00
New Revision: 761f3d16753ecea625173729dd8c53df022cd4ab

URL: https://github.com/llvm/llvm-project/commit/761f3d16753ecea625173729dd8c53df022cd4ab
DIFF: https://github.com/llvm/llvm-project/commit/761f3d16753ecea625173729dd8c53df022cd4ab.diff

LOG: [clang][PreProcessor] Cutoff parsing after hitting completion point

This fixes a crash caused by Lexers being invalidated at code
completion points in
https://github.com/llvm/llvm-project/blob/main/clang/lib/Lex/PPLexerChange.cpp#L520.

Differential Revision: https://reviews.llvm.org/D102069

Added: 
    clang/test/CodeCompletion/crash-if-directive.cpp

Modified: 
    clang/lib/Lex/PPDirectives.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index a771b7c5d122d..d5cb46f75aec3 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -595,6 +595,9 @@ void Preprocessor::SkipExcludedConditionalBlock(SourceLocation HashTokenLoc,
           CurPPLexer->LexingRawMode = false;
           IdentifierInfo *IfNDefMacro = nullptr;
           DirectiveEvalResult DER = EvaluateDirectiveExpression(IfNDefMacro);
+          // Stop if Lexer became invalid after hitting code completion token.
+          if (!CurPPLexer)
+            return;
           const bool CondValue = DER.Conditional;
           CurPPLexer->LexingRawMode = true;
           if (Callbacks) {
@@ -3023,6 +3026,10 @@ void Preprocessor::HandleIfDirective(Token &IfToken,
   IdentifierInfo *IfNDefMacro = nullptr;
   const DirectiveEvalResult DER = EvaluateDirectiveExpression(IfNDefMacro);
   const bool ConditionalTrue = DER.Conditional;
+  // Lexer might become invalid if we hit code completion point while evaluating
+  // expression.
+  if (!CurPPLexer)
+    return;
 
   // If this condition is equivalent to #ifndef X, and if this is the first
   // directive seen, handle it for the multiple-include optimization.

diff  --git a/clang/test/CodeCompletion/crash-if-directive.cpp b/clang/test/CodeCompletion/crash-if-directive.cpp
new file mode 100644
index 0000000000000..0878c5c871e0c
--- /dev/null
+++ b/clang/test/CodeCompletion/crash-if-directive.cpp
@@ -0,0 +1,6 @@
+#define FOO(X) X
+#if FOO(
+#elif FOO(
+#endif
+// RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:2:9 %s
+// RUN: not %clang_cc1 -fsyntax-only -code-completion-at=%s:3:11 %s