[core] fix accessing empty vector

ferdymercury · dpiparo · commit bd6202715aba · 2025-10-30T22:12:37.000+01:00
Fixes https://root-forum.cern.ch/t/tinterpreter-crash/64364
diff --git a/core/metacling/src/TCling.cxx b/core/metacling/src/TCling.cxx
@@ -5484,7 +5484,7 @@ Longptr_t TCling::ExecuteMacro(const char* filename, EErrorCode* error)
 const char* TCling::GetTopLevelMacroName() const
 {
    Warning("GetTopLevelMacroName", "Must change return type!");
-   return fCurExecutingMacros.back();
+   return fCurExecutingMacros.empty() ? nullptr : fCurExecutingMacros.back();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -5535,7 +5535,7 @@ const char* TCling::GetCurrentMacroName() const
    Warning("GetCurrentMacroName", "Must change return type!");
 #endif
 #endif
-   return fCurExecutingMacros.back();
+   return fCurExecutingMacros.empty() ? nullptr : fCurExecutingMacros.back();
 }
 
 ////////////////////////////////////////////////////////////////////////////////

Original file line number	Diff line number	Diff line change
`@@ -5484,7 +5484,7 @@ Longptr_t TCling::ExecuteMacro(const char* filename, EErrorCode* error)`
`5484`	`5484`	`const char* TCling::GetTopLevelMacroName() const`
`5485`	`5485`	`{`
`5486`	`5486`	`Warning("GetTopLevelMacroName", "Must change return type!");`
`5487`		`- return fCurExecutingMacros.back();`
	`5487`	`+ return fCurExecutingMacros.empty() ? nullptr : fCurExecutingMacros.back();`
`5488`	`5488`	`}`
`5489`	`5489`
`5490`	`5490`	`////////////////////////////////////////////////////////////////////////////////`
`@@ -5535,7 +5535,7 @@ const char* TCling::GetCurrentMacroName() const`
`5535`	`5535`	`Warning("GetCurrentMacroName", "Must change return type!");`
`5536`	`5536`	`#endif`
`5537`	`5537`	`#endif`
`5538`		`- return fCurExecutingMacros.back();`
	`5538`	`+ return fCurExecutingMacros.empty() ? nullptr : fCurExecutingMacros.back();`
`5539`	`5539`	`}`
`5540`	`5540`
`5541`	`5541`	`////////////////////////////////////////////////////////////////////////////////`