[clang-repl] fix segfault in CleanUpPTU()

[p4vook]

Check if the last translation unit or its first declaration are actually empty and do not nead cleanup.

Previously this caused segmentation fault on empty PTUs.

Add a regression test.

Fixes: #72980

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[llvmbot]

@llvm/pr-subscribers-clang

Author: Pavel Kalugin (p4vook)

Changes

Check if the last translation unit or its first declaration are actually empty and do not nead cleanup.

Previously this caused segmentation fault on empty PTUs.

Add a regression test.

Fixes: #72980

---

Full diff: https://github.com/llvm/llvm-project/pull/75629.diff

2 Files Affected:

• (modified) clang/lib/Interpreter/IncrementalParser.cpp (+8)
• (added) clang/test/Interpreter/anonymous-scope-fail.cpp (+10)

diff --git a/clang/lib/Interpreter/IncrementalParser.cpp b/clang/lib/Interpreter/IncrementalParser.cpp
index 370bcbfee8b014..f894af881134bb 100644
--- a/clang/lib/Interpreter/IncrementalParser.cpp
+++ b/clang/lib/Interpreter/IncrementalParser.cpp
@@ -373,7 +373,15 @@ std::unique_ptr<llvm::Module> IncrementalParser::GenModule() {
 
 void IncrementalParser::CleanUpPTU(PartialTranslationUnit &PTU) {
   TranslationUnitDecl *MostRecentTU = PTU.TUPart;
+  if (!MostRecentTU) {
+    return;
+  }
+
   TranslationUnitDecl *FirstTU = MostRecentTU->getFirstDecl();
+  if (!FirstTU) {
+    return;
+  }
+
   if (StoredDeclsMap *Map = FirstTU->getPrimaryContext()->getLookupPtr()) {
     for (auto I = Map->begin(); I != Map->end(); ++I) {
       StoredDeclsList &List = I->second;
diff --git a/clang/test/Interpreter/anonymous-scope-fail.cpp b/clang/test/Interpreter/anonymous-scope-fail.cpp
new file mode 100644
index 00000000000000..c32b42d2859d97
--- /dev/null
+++ b/clang/test/Interpreter/anonymous-scope-fail.cpp
@@ -0,0 +1,10 @@
+// RUN: clang-repl "int x = 10;" "{ int t; a::b(t); }" "int y = 10;"
+// REQUIRES: host-supports-jit
+// UNSUPPORTED: system-aix
+// RUN: cat %s | not clang-repl | FileCheck %s
+{ int t; a::b(t); }
+extern "C" int printf(const char *, ...);
+int i = 42;
+auto r1 = printf("i = %d\n", i);
+// CHECK: i = 42
+%quit

[vgvassilev]

Can you move this in the code-undo.cpp test?

[p4vook]

I don't quite understand, the code-undo.cpp doesn't seem to have anything that produces an error, but this test does.
If we define a::b(t), clang-repl stops segfaulting here.
Is it okay to put tests with errors into code-undo.cpp?

[vgvassilev]

Then we can put it in a new file called error-recovery.cpp.

[vgvassilev]

@p4vook ping.

[p4vook]

Yep, we can, I'll try to do it this evening. I couldn't figure out why this test failed though, I probably need to fix it somehow.

[p4vook]

I converted the PR to draft, as this seems to be a part of a bigger problem with inserting statements into wrong nodes of the syntax tree (this seems to only show up when namespaces are present). I believe it shouldn't be fixed just by a simple check for nullptr.