Exception utils: remove redundant what() implementations

Make a `std::string reason` a member of the base class, and make
`what()` default to returning `reason`. This avoids duplicating the same
implementation across several child classes.

While at it, also fix the missing init-to-nil in one of
incorrect_goto_program_exceptiont's constructors.

Author: tautschnig

src/goto-programs/restrict_function_pointers.cpp

@@ -87,7 +87,8 @@ static void restrict_function_pointer(
 invalid_restriction_exceptiont::invalid_restriction_exceptiont(
   std::string reason,
   std::string correct_format)
-  : reason(std::move(reason)), correct_format(std::move(correct_format))
+  : cprover_exception_baset(std::move(reason)),
+    correct_format(std::move(correct_format))
 {
 }
 

src/goto-programs/slice_global_inits.h

@@ -23,17 +23,9 @@ class user_input_error_exceptiont : public cprover_exception_baset
 {
 public:
   explicit user_input_error_exceptiont(std::string message)
-    : message(std::move(message))
+    : cprover_exception_baset(std::move(message))
   {
   }
-
-  std::string what() const override
-  {
-    return message;
-  }
-
-private:
-  std::string message;
 };
 
 /// Remove initialization of global variables that are not used in any function

src/goto-programs/string_instrumentation.h

@@ -26,16 +26,16 @@ class incorrect_source_program_exceptiont : public cprover_exception_baset
   incorrect_source_program_exceptiont(
     std::string message,
     source_locationt source_location)
-    : message(std::move(message)), source_location(std::move(source_location))
+    : cprover_exception_baset(std::move(message)),
+      source_location(std::move(source_location))
   {
   }
   std::string what() const override
   {
-    return message + " (at: " + source_location.as_string() + ")";
+    return reason + " (at: " + source_location.as_string() + ")";
   }
 
 private:
-  std::string message;
   source_locationt source_location;
 };
 

src/memory-analyzer/gdb_api.h

@@ -229,16 +229,10 @@ class gdb_apit
 class gdb_interaction_exceptiont : public cprover_exception_baset
 {
 public:
-  explicit gdb_interaction_exceptiont(std::string reason) : reason(reason)
+  explicit gdb_interaction_exceptiont(std::string reason)
+    : cprover_exception_baset(std::move(reason))
   {
   }
-  std::string what() const override
-  {
-    return reason;
-  }
-
-private:
-  std::string reason;
 };
 
 #endif // CPROVER_MEMORY_ANALYZER_GDB_API_H

src/solvers/smt2/smt2_tokenizer.h

@@ -9,8 +9,6 @@ Author: Daniel Kroening, kroening@kroening.com
 #ifndef CPROVER_SOLVERS_SMT2_SMT2_TOKENIZER_H
 #define CPROVER_SOLVERS_SMT2_SMT2_TOKENIZER_H
 
-#include <util/exception_utils.h>
-
 #include <sstream>
 #include <string>
 
@@ -23,7 +21,7 @@ class smt2_tokenizert
     line_no=1;
   }
 
-  class smt2_errort : public cprover_exception_baset
+  class smt2_errort
   {
   public:
     smt2_errort(const std::string &_message, unsigned _line_no)
@@ -36,7 +34,7 @@ class smt2_tokenizert
     {
     }
 
-    std::string what() const override
+    std::string what() const
     {
       return message.str();
     }

src/util/exception_utils.cpp

@@ -9,6 +9,11 @@ Author: Fotis Koutoulakis, fotis.koutoulakis@diffblue.com
 #include "exception_utils.h"
 #include <utility>
 
+std::string cprover_exception_baset::what() const
+{
+  return reason;
+}
+
 std::string invalid_command_line_argument_exceptiont::what() const
 {
   std::string res;
@@ -28,42 +33,32 @@ invalid_command_line_argument_exceptiont::
     std::string reason,
     std::string option,
     std::string correct_input)
-  : reason(std::move(reason)),
+  : cprover_exception_baset(std::move(reason)),
     option(std::move(option)),
     correct_input(std::move(correct_input))
 {
 }
 
 system_exceptiont::system_exceptiont(std::string message)
-  : message(std::move(message))
+  : cprover_exception_baset(std::move(message))
 {
 }
 
-std::string system_exceptiont::what() const
-{
-  return message;
-}
-
 deserialization_exceptiont::deserialization_exceptiont(std::string message)
-  : message(std::move(message))
+  : cprover_exception_baset(std::move(message))
 {
 }
 
-std::string deserialization_exceptiont::what() const
-{
-  return message;
-}
-
 incorrect_goto_program_exceptiont::incorrect_goto_program_exceptiont(
   std::string message)
-  : message(std::move(message))
+  : cprover_exception_baset(std::move(message)),
+    source_location(source_locationt::nil())
 {
-  source_location.make_nil();
 }
 
 std::string incorrect_goto_program_exceptiont::what() const
 {
-  std::string ret(message);
+  std::string ret(reason);
 
   if(!source_location.is_nil())
     ret += " (at: " + source_location.as_string() + ")";
@@ -76,32 +71,17 @@ std::string incorrect_goto_program_exceptiont::what() const
 
 unsupported_operation_exceptiont::unsupported_operation_exceptiont(
   std::string message)
-  : message(std::move(message))
+  : cprover_exception_baset(std::move(message))
 {
 }
 
-std::string unsupported_operation_exceptiont::what() const
-{
-  return message;
-}
-
 analysis_exceptiont::analysis_exceptiont(std::string reason)
-  : reason(std::move(reason))
-{
-}
-
-std::string analysis_exceptiont::what() const
+  : cprover_exception_baset(std::move(reason))
 {
-  return reason;
 }
 
 invalid_source_file_exceptiont::invalid_source_file_exceptiont(
   std::string reason)
-  : reason(std::move(reason))
+  : cprover_exception_baset(std::move(reason))
 {
 }
-
-std::string invalid_source_file_exceptiont::what() const
-{
-  return reason;
-}

src/util/exception_utils.h

@@ -27,17 +27,28 @@ class cprover_exception_baset
   /// A human readable description of what went wrong.
   /// For readability, implementors should not add a leading
   /// or trailing newline to this description.
-  virtual std::string what() const = 0;
+  virtual std::string what() const;
   virtual ~cprover_exception_baset() = default;
+
+protected:
+  /// This constructor is marked protected to ensure this class isn't used
+  /// directly. Deriving classes should be used to more precisely describe the
+  /// problem that occurred.
+  explicit cprover_exception_baset(std::string reason)
+    : reason(std::move(reason))
+  {
+  }
+
+  /// The reason this exception was generated. This is the string returned by
+  /// `what()` unless that method is overridden
+  std::string reason;
 };
 
 /// Thrown when users pass incorrect command line arguments,
 /// for example passing no files to analysis or setting
 /// two mutually exclusive flags
 class invalid_command_line_argument_exceptiont : public cprover_exception_baset
 {
-  /// The reason this exception was generated.
-  std::string reason;
   /// The full command line option (not the argument) that got
   /// erroneous input.
   std::string option;
@@ -61,10 +72,6 @@ class system_exceptiont : public cprover_exception_baset
 {
 public:
   explicit system_exceptiont(std::string message);
-  std::string what() const override;
-
-private:
-  std::string message;
 };
 
 /// Thrown when failing to deserialize a value from some
@@ -73,11 +80,6 @@ class deserialization_exceptiont : public cprover_exception_baset
 {
 public:
   explicit deserialization_exceptiont(std::string message);
-
-  std::string what() const override;
-
-private:
-  std::string message;
 };
 
 /// Thrown when a goto program that's being processed is in an invalid format,
@@ -106,7 +108,6 @@ class incorrect_goto_program_exceptiont : public cprover_exception_baset
   std::string what() const override;
 
 private:
-  std::string message;
   source_locationt source_location;
 
   std::string diagnostics;
@@ -117,8 +118,8 @@ incorrect_goto_program_exceptiont::incorrect_goto_program_exceptiont(
   std::string message,
   Diagnostic &&diagnostic,
   Diagnostics &&... diagnostics)
-  : message(std::move(message)),
-    source_location(),
+  : cprover_exception_baset(std::move(message)),
+    source_location(source_locationt::nil()),
     diagnostics(detail::assemble_diagnostics(
       std::forward<Diagnostic>(diagnostic),
       std::forward<Diagnostics>(diagnostics)...))
@@ -130,7 +131,7 @@ incorrect_goto_program_exceptiont::incorrect_goto_program_exceptiont(
   std::string message,
   source_locationt source_location,
   Diagnostics &&... diagnostics)
-  : message(std::move(message)),
+  : cprover_exception_baset(std::move(message)),
     source_location(std::move(source_location)),
     diagnostics(
       detail::assemble_diagnostics(std::forward<Diagnostics>(diagnostics)...))
@@ -143,12 +144,8 @@ incorrect_goto_program_exceptiont::incorrect_goto_program_exceptiont(
 class unsupported_operation_exceptiont : public cprover_exception_baset
 {
 public:
+  /// \p message is the unsupported operation causing this fault to occur.
   explicit unsupported_operation_exceptiont(std::string message);
-  std::string what() const override;
-
-private:
-  /// The unsupported operation causing this fault to occur.
-  std::string message;
 };
 
 /// Thrown when an unexpected error occurs during the analysis (e.g., when the
@@ -157,11 +154,6 @@ class analysis_exceptiont : public cprover_exception_baset
 {
 public:
   explicit analysis_exceptiont(std::string reason);
-  std::string what() const override;
-
-private:
-  /// The reason this exception was generated.
-  std::string reason;
 };
 
 /// Thrown when we can't handle something in an input source file.
@@ -171,10 +163,6 @@ class invalid_source_file_exceptiont : public cprover_exception_baset
 {
 public:
   explicit invalid_source_file_exceptiont(std::string reason);
-  std::string what() const override;
-
-private:
-  std::string reason;
 };
 
 #endif // CPROVER_UTIL_EXCEPTION_UTILS_H