[clang] [clang] Prevent dangling StringRefs (PR #98699)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Youngsuk Kim (JOE1994)

<details>
<summary>Changes</summary>

Fix locations where dangling StringRefs are created.

* `ConstraintSatisfaction::SubstitutionDiagnostic`: typedef of 
`std::pair&lt;SourceLocation, StringRef&gt;`

* `concepts::Requirement::SubstitutionDiagnostic`: struct whose 1st and 3rd 
data members are `StringRef`s

Fixes #<!-- -->98667

---
Full diff: https://github.com/llvm/llvm-project/pull/98699.diff


1 Files Affected:

- (modified) clang/lib/Serialization/ASTReaderStmt.cpp (+16-5) 


``````````diff
diff --git a/clang/lib/Serialization/ASTReaderStmt.cpp 
b/clang/lib/Serialization/ASTReaderStmt.cpp
index 5a5d7be69a2c3..ecbc57d642ca7 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -797,10 +797,14 @@ readConstraintSatisfaction(ASTRecordReader &Record) {
       if (/* IsDiagnostic */Record.readInt()) {
         SourceLocation DiagLocation = Record.readSourceLocation();
         std::string DiagMessage = Record.readString();
+        char *DBuf = new (Record.getContext()) char[DiagMessage.size()];
+        std::copy(DiagMessage.begin(), DiagMessage.end(), DBuf);
+
         Satisfaction.Details.emplace_back(
-            ConstraintExpr, new (Record.getContext())
-                                ConstraintSatisfaction::SubstitutionDiagnostic{
-                                    DiagLocation, DiagMessage});
+            ConstraintExpr,
+            new (Record.getContext())
+                ConstraintSatisfaction::SubstitutionDiagnostic{
+                    DiagLocation, StringRef(DBuf, DiagMessage.size())});
       } else
         Satisfaction.Details.emplace_back(ConstraintExpr, Record.readExpr());
     }
@@ -822,11 +826,18 @@ void ASTStmtReader::VisitConceptSpecializationExpr(
 static concepts::Requirement::SubstitutionDiagnostic *
 readSubstitutionDiagnostic(ASTRecordReader &Record) {
   std::string SubstitutedEntity = Record.readString();
+  char *SBuf = new (Record.getContext()) char[SubstitutedEntity.size()];
+  std::copy(SubstitutedEntity.begin(), SubstitutedEntity.end(), SBuf);
+
   SourceLocation DiagLoc = Record.readSourceLocation();
   std::string DiagMessage = Record.readString();
+  char *DBuf = new (Record.getContext()) char[DiagMessage.size()];
+  std::copy(DiagMessage.begin(), DiagMessage.end(), DBuf);
+
   return new (Record.getContext())
-      concepts::Requirement::SubstitutionDiagnostic{SubstitutedEntity, DiagLoc,
-                                                    DiagMessage};
+      concepts::Requirement::SubstitutionDiagnostic{
+          StringRef(SBuf, SubstitutedEntity.size()), DiagLoc,
+          StringRef(DBuf, DiagMessage.size())};
 }
 
 void ASTStmtReader::VisitRequiresExpr(RequiresExpr *E) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/98699
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