Change

changes.rst

@@ -57,6 +57,8 @@ Bug fixes:
 -  Ensure reverse mappers are created when flattening tuple/record literals.
    This resolves certain errors during output processing in models using these
    types.
+-  Fix problem where certain strings in exceptions might be garbage collected
+   before they are output (:bugref:`725`).
 
 .. _v2.7.6:
 

include/minizinc/astexception.hh

@@ -13,40 +13,24 @@
 
 #include <minizinc/ast.hh>
 #include <minizinc/exception.hh>
+#include <minizinc/gc.hh>
 #include <minizinc/model.hh>
 #include <minizinc/stackdump.hh>
 
 #include <string>
 
 namespace MiniZinc {
 
-class SyntaxError : public Exception {
+class CyclicIncludeError : public Exception, public GCMarker {
 protected:
-  Location _loc;
-  std::string _currentLine;
-  std::vector<ASTString> _includeStack;
-
-public:
-  SyntaxError(const Location& loc, const std::string& msg) : Exception(msg) {}
-  SyntaxError(const Location& loc, std::string currentLine, std::vector<ASTString> includeStack,
-              const std::string& msg)
-      : Exception(msg),
-        _loc(loc),
-        _currentLine(std::move(currentLine)),
-        _includeStack(std::move(includeStack)) {}
-  ~SyntaxError() throw() override {}
-  const char* what() const throw() override { return "syntax error"; }
-  const Location& loc() const { return _loc; }
-
-  void print(std::ostream& os) const override;
-  void json(std::ostream& os) const override;
-};
-
-class CyclicIncludeError : public Exception {
-protected:
-  Location _loc;
   std::vector<ASTString> _cycle;
 
+  void mark() override {
+    for (auto s : _cycle) {
+      s.mark();
+    }
+  }
+
 public:
   CyclicIncludeError(std::vector<ASTString> cycle) : Exception(""), _cycle(std::move(cycle)) {}
   ~CyclicIncludeError() throw() override {}
@@ -68,6 +52,7 @@ protected:
   }
 
 public:
+  LocationException(const Location& loc, const std::string& msg);
   LocationException(EnvI& env, const Location& loc, const std::string& msg);
   ~LocationException() throw() override {}
   const Location& loc() const { return _loc; }
@@ -79,6 +64,32 @@ public:
   void json(std::ostream& os) const override;
 };
 
+class SyntaxError : public LocationException {
+protected:
+  std::string _currentLine;
+  std::vector<ASTString> _includeStack;
+
+  void mark() override {
+    LocationException::mark();
+    for (auto s : _includeStack) {
+      s.mark();
+    }
+  }
+
+public:
+  SyntaxError(const Location& loc, const std::string& msg) : LocationException(loc, msg) {}
+  SyntaxError(const Location& loc, std::string currentLine, std::vector<ASTString> includeStack,
+              const std::string& msg)
+      : LocationException(loc, msg),
+        _currentLine(std::move(currentLine)),
+        _includeStack(std::move(includeStack)) {}
+  ~SyntaxError() throw() override {}
+  const char* what() const throw() override { return "syntax error"; }
+
+  void print(std::ostream& os) const override;
+  void json(std::ostream& os) const override;
+};
+
 class IncludeError : public LocationException {
 public:
   IncludeError(EnvI& env, const Location& loc, const std::string& msg)

include/minizinc/stackdump.hh

@@ -25,6 +25,7 @@ class Expression;
 class StackDump {
 public:
   StackDump(EnvI& env);
+  StackDump() {}
   void print(std::ostream& os) const;
   void json(std::ostream& os) const;
   bool empty() const { return _stack.empty(); }

lib/astexception.cpp

@@ -69,6 +69,9 @@ void CyclicIncludeError::json(std::ostream& os) const {
 LocationException::LocationException(EnvI& env, const Location& loc, const std::string& msg)
     : Exception(msg), _stack(env), _loc(loc) {}
 
+LocationException::LocationException(const Location& loc, const std::string& msg)
+    : Exception(msg), _loc(loc) {}
+
 void LocationException::print(std::ostream& os) const {
   Exception::print(os);
   if (_dumpStack) {