Make use of operator<<(ostream, exception)

26 files changed, 112 insertions, 111 deletions

diff --git a/build2/b.cxx b/build2/b.cxx
index 7b9460b..bd77a02 100644
--- a/build2/b.cxx
+++ b/build2/b.cxx
@@ -201,7 +201,7 @@ main (int argc, char* argv[])
       //
       catch (const system_error& e)
       {
-        error << "pager failed: " << e.what ();
+        error << "pager failed: " << e;
         return 1;
       }
     }
diff --git a/build2/bin/init.cxx b/build2/bin/init.cxx
index 89dea09..e1b812b 100644
--- a/build2/bin/init.cxx
+++ b/build2/bin/init.cxx
@@ -246,8 +246,7 @@ namespace build2
             // This is where we suggest that the user specifies --config-sub
             // to help us out.
             //
-            fail << "unable to parse binutils target '" << s << "': "
-                 << e.what () <<
+            fail << "unable to parse binutils target '" << s << "': " << e <<
               info << "consider using the --config-sub option";
           }
 
diff --git a/build2/cc/compile.cxx b/build2/cc/compile.cxx
index 1b34c69..6fd64c2 100644
--- a/build2/cc/compile.cxx
+++ b/build2/cc/compile.cxx
@@ -1370,7 +1370,7 @@ namespace build2
           }
           catch (const process_error& e)
           {
-            error << "unable to execute " << args[0] << ": " << e.what ();
+            error << "unable to execute " << args[0] << ": " << e;
 
             // In a multi-threaded program that fork()'ed but did not exec(),
             // it is unwise to try to do any kind of cleanup (like unwinding
@@ -1596,7 +1596,7 @@ namespace build2
       }
       catch (const process_error& e)
       {
-        error << "unable to execute " << args[0] << ": " << e.what ();
+        error << "unable to execute " << args[0] << ": " << e;
 
         // In a multi-threaded program that fork()'ed but did not exec(),
         // it is unwise to try to do any kind of cleanup (like unwinding
diff --git a/build2/cc/gcc.cxx b/build2/cc/gcc.cxx
index c778493..6ad1ad1 100644
--- a/build2/cc/gcc.cxx
+++ b/build2/cc/gcc.cxx
@@ -90,7 +90,7 @@ namespace build2
       }
       catch (const process_error& e)
       {
-        error << "unable to execute " << args[0] << ": " << e.what ();
+        error << "unable to execute " << args[0] << ": " << e;
 
         if (e.child ())
           exit (1);
diff --git a/build2/cc/link.cxx b/build2/cc/link.cxx
index f55013f..9dbfa36 100644
--- a/build2/cc/link.cxx
+++ b/build2/cc/link.cxx
@@ -978,12 +978,12 @@ namespace build2
               {
                 if (pr.wait ()) // Ignore if child failed.
                   fail << "unable to pipe resource file to " << args[0]
-                       << ": " << e.what ();
+                       << ": " << e;
               }
             }
             catch (const process_error& e)
             {
-              error << "unable to execute " << args[0] << ": " << e.what ();
+              error << "unable to execute " << args[0] << ": " << e;
 
               if (e.child ())
                 exit (1);
@@ -1498,7 +1498,7 @@ namespace build2
       }
       catch (const process_error& e)
       {
-        error << "unable to execute " << args[0] << ": " << e.what ();
+        error << "unable to execute " << args[0] << ": " << e;
 
         // In a multi-threaded program that fork()'ed but did not exec(),
         // it is unwise to try to do any kind of cleanup (like unwinding
@@ -1536,7 +1536,7 @@ namespace build2
         }
         catch (const process_error& e)
         {
-          error << "unable to execute " << args[0] << ": " << e.what ();
+          error << "unable to execute " << args[0] << ": " << e;
 
           if (e.child ())
             exit (1);
@@ -1577,7 +1577,7 @@ namespace build2
           }
           catch (const system_error& e)
           {
-            fail << "unable to create symlink " << l << ": " << e.what ();
+            fail << "unable to create symlink " << l << ": " << e;
           }
         };
 
diff --git a/build2/cc/module.cxx b/build2/cc/module.cxx
index 067aea3..40bd454 100644
--- a/build2/cc/module.cxx
+++ b/build2/cc/module.cxx
@@ -115,7 +115,7 @@ namespace build2
           // help us out.
           //
           fail << "unable to parse " << x_lang << " compiler target '"
-               << ci.target << "': " << e.what () <<
+               << ci.target << "': " << e <<
             info << "consider using the --config-sub option";
         }
       }
diff --git a/build2/cc/windows-manifest.cxx b/build2/cc/windows-manifest.cxx
index c4e86e4..44d8f7b 100644
--- a/build2/cc/windows-manifest.cxx
+++ b/build2/cc/windows-manifest.cxx
@@ -127,7 +127,7 @@ namespace build2
       }
       catch (const io_error& e)
       {
-        fail << "unable to write to " << m << ": " << e.what ();
+        fail << "unable to write to " << m << ": " << e;
       }
 
       return mf;
diff --git a/build2/cc/windows-rpath.cxx b/build2/cc/windows-rpath.cxx
index aa1d740..35d83cc 100644
--- a/build2/cc/windows-rpath.cxx
+++ b/build2/cc/windows-rpath.cxx
@@ -311,7 +311,7 @@ namespace build2
             if (c != EPERM && c != ENOSYS)
             {
               print ("ln -s");
-              fail << "unable to create symlink " << l << ": " << e.what ();
+              fail << "unable to create symlink " << l << ": " << e;
             }
 
             try
@@ -326,7 +326,7 @@ namespace build2
               if (c != EPERM && c != ENOSYS)
               {
                 print ("ln");
-                fail << "unable to create hardlink " << l << ": " << e.what ();
+                fail << "unable to create hardlink " << l << ": " << e;
               }
 
               try
@@ -337,7 +337,7 @@ namespace build2
               catch (const system_error& e)
               {
                 print ("cp");
-                fail << "unable to create copy " << l << ": " << e.what ();
+                fail << "unable to create copy " << l << ": " << e;
               }
             }
           }
@@ -371,7 +371,7 @@ namespace build2
       }
       catch (const io_error& e)
       {
-        fail << "unable to write to " << am << ": " << e.what ();
+        fail << "unable to write to " << am << ": " << e;
       }
     }
   }
diff --git a/build2/cli/init.cxx b/build2/cli/init.cxx
index ead067a..45e2655 100644
--- a/build2/cli/init.cxx
+++ b/build2/cli/init.cxx
@@ -157,7 +157,7 @@ namespace build2
             // found). So it would be good to redirect child's STDERR.
             //
             if (!optional)
-              error << "unable to execute " << args[0] << ": " << e.what ();
+              error << "unable to execute " << args[0] << ": " << e;
 
             if (e.child ())
               exit (1);
diff --git a/build2/cli/rule.cxx b/build2/cli/rule.cxx
index 59a5d66..5b78723 100644
--- a/build2/cli/rule.cxx
+++ b/build2/cli/rule.cxx
@@ -301,7 +301,7 @@ namespace build2
       }
       catch (const process_error& e)
       {
-        error << "unable to execute " << args[0] << ": " << e.what ();
+        error << "unable to execute " << args[0] << ": " << e;
 
         if (e.child ())
           exit (1);
diff --git a/build2/config/operation.cxx b/build2/config/operation.cxx
index 7fdd682..3370c2c 100644
--- a/build2/config/operation.cxx
+++ b/build2/config/operation.cxx
@@ -57,7 +57,7 @@ namespace build2
       }
       catch (const io_error& e)
       {
-        fail << "unable to write " << f << ": " << e.what ();
+        fail << "unable to write " << f << ": " << e;
       }
     }
 
@@ -277,7 +277,7 @@ namespace build2
       }
       catch (const io_error& e)
       {
-        fail << "unable to write " << f << ": " << e.what ();
+        fail << "unable to write " << f << ": " << e;
       }
     }
 
diff --git a/build2/context.cxx b/build2/context.cxx
index 38c726d..106b7ec 100644
--- a/build2/context.cxx
+++ b/build2/context.cxx
@@ -299,7 +299,7 @@ namespace build2
       }
       catch (const invalid_argument& e)
       {
-        fail << "unable to parse build host '" << orig << "': " << e.what () <<
+        fail << "unable to parse build host '" << orig << "': " << e <<
           info << "consider using the --config-guess option";
       }
     }
diff --git a/build2/dist/operation.cxx b/build2/dist/operation.cxx
index a662287..47e188c 100644
--- a/build2/dist/operation.cxx
+++ b/build2/dist/operation.cxx
@@ -338,7 +338,7 @@ namespace build2
       }
       catch (const process_error& e)
       {
-        error << "unable to execute " << args[0] << ": " << e.what ();
+        error << "unable to execute " << args[0] << ": " << e;
 
         if (e.child ())
           exit (1);
@@ -392,7 +392,7 @@ namespace build2
       }
       catch (const process_error& e)
       {
-        error << "unable to execute " << args[0] << ": " << e.what ();
+        error << "unable to execute " << args[0] << ": " << e;
 
         if (e.child ())
           exit (1);
@@ -444,7 +444,7 @@ namespace build2
       }
       catch (const process_error& e)
       {
-        error << "unable to execute " << args[0] << ": " << e.what ();
+        error << "unable to execute " << args[0] << ": " << e;
 
         if (e.child ())
           exit (1);
diff --git a/build2/file.cxx b/build2/file.cxx
index 83dcacf..cc1be77 100644
--- a/build2/file.cxx
+++ b/build2/file.cxx
@@ -107,7 +107,7 @@ namespace build2
     }
     catch (const io_error& e)
     {
-      fail << "unable to read buildfile " << bf << ": " << e.what ();
+      fail << "unable to read buildfile " << bf << ": " << e;
     }
   }
 
@@ -307,7 +307,7 @@ namespace build2
     }
     catch (const io_error& e)
     {
-      fail << "unable to read buildfile " << bf << ": " << e.what () << endf;
+      fail << "unable to read buildfile " << bf << ": " << e << endf;
     }
 
     // Never reached.
@@ -1087,7 +1087,7 @@ namespace build2
     }
     catch (const io_error& e)
     {
-      fail (loc) << "unable to read buildfile " << es << ": " << e.what ();
+      fail (loc) << "unable to read buildfile " << es << ": " << e;
     }
 
     return names (); // Never reached.
diff --git a/build2/filesystem.cxx b/build2/filesystem.cxx
index 798f002..86bdff8 100644
--- a/build2/filesystem.cxx
+++ b/build2/filesystem.cxx
@@ -28,7 +28,7 @@ namespace build2
       if (verb >= v)
         text << "mkdir " << d;
 
-      fail << "unable to create directory " << d << ": " << e.what () << endf;
+      fail << "unable to create directory " << d << ": " << e << endf;
     }
 
     if (ms == mkdir_status::success)
@@ -57,7 +57,7 @@ namespace build2
       if (verb >= v)
         text << "mkdir -p " << d;
 
-      fail << "unable to create directory " << d << ": " << e.what () << endf;
+      fail << "unable to create directory " << d << ": " << e << endf;
     }
 
     if (ms == mkdir_status::success)
@@ -89,7 +89,7 @@ namespace build2
     }
     catch (const system_error& e)
     {
-      fail << "unable to remove directory " << d << ": " << e.what ();
+      fail << "unable to remove directory " << d << ": " << e;
     }
 
     return rmdir_status::success;
@@ -104,7 +104,7 @@ namespace build2
     }
     catch (const system_error& e)
     {
-      fail << "unable to stat path " << f << ": " << e.what () << endf;
+      fail << "unable to stat path " << f << ": " << e << endf;
     }
   }
 
@@ -117,7 +117,7 @@ namespace build2
     }
     catch (const system_error& e)
     {
-      fail << "unable to stat path " << d << ": " << e.what () << endf;
+      fail << "unable to stat path " << d << ": " << e << endf;
     }
   }
 
@@ -130,7 +130,7 @@ namespace build2
     }
     catch (const system_error& e)
     {
-      fail << "unable to stat path " << p << ": " << e.what () << endf;
+      fail << "unable to stat path " << p << ": " << e << endf;
     }
   }
 
@@ -143,7 +143,7 @@ namespace build2
     }
     catch (const system_error& e)
     {
-      fail << "unable to scan directory " << d << ": " << e.what () << endf;
+      fail << "unable to scan directory " << d << ": " << e << endf;
     }
   }
 }
diff --git a/build2/filesystem.txx b/build2/filesystem.txx
index 5a4838e..708c75e 100644
--- a/build2/filesystem.txx
+++ b/build2/filesystem.txx
@@ -37,7 +37,7 @@ namespace build2
     catch (const system_error& e)
     {
       print ();
-      error << "unable to remove file " << f << ": " << e.what ();
+      error << "unable to remove file " << f << ": " << e;
       throw failed ();
     }
 
@@ -78,7 +78,7 @@ namespace build2
     catch (const system_error& e)
     {
       print ();
-      error << "unable to remove directory " << d << ": " << e.what ();
+      error << "unable to remove directory " << d << ": " << e;
       throw failed ();
     }
 
diff --git a/build2/function.cxx b/build2/function.cxx
index c3a08c1..eeb332f 100644
--- a/build2/function.cxx
+++ b/build2/function.cxx
@@ -249,9 +249,8 @@ namespace build2
     diag_record dr (fail);
     dr << "invalid argument";
 
-    const char* w (e.what ());
-    if (*w != '\0')
-      dr << ": " << w;
+    if (*e.what () != '\0')
+      dr << ": " << e;
 
     dr << endf;
   }
diff --git a/build2/install/rule.cxx b/build2/install/rule.cxx
index 1c21a1c..a368ac9 100644
--- a/build2/install/rule.cxx
+++ b/build2/install/rule.cxx
@@ -425,7 +425,7 @@ namespace build2
       }
       catch (const system_error& e)
       {
-        fail << "invalid installation directory " << d << ": " << e.what ();
+        fail << "invalid installation directory " << d << ": " << e;
       }
 
       // While install -d will create all the intermediate components between
@@ -477,7 +477,7 @@ namespace build2
       }
       catch (const process_error& e)
       {
-        error << "unable to execute " << args[0] << ": " << e.what ();
+        error << "unable to execute " << args[0] << ": " << e;
 
         if (e.child ())
           exit (1);
@@ -543,7 +543,7 @@ namespace build2
       }
       catch (const process_error& e)
       {
-        error << "unable to execute " << args[0] << ": " << e.what ();
+        error << "unable to execute " << args[0] << ": " << e;
 
         if (e.child ())
           exit (1);
@@ -592,7 +592,7 @@ namespace build2
       }
       catch (const process_error& e)
       {
-        error << "unable to execute " << args[0] << ": " << e.what ();
+        error << "unable to execute " << args[0] << ": " << e;
 
         if (e.child ())
           exit (1);
@@ -690,7 +690,7 @@ namespace build2
       }
       catch (const system_error& e)
       {
-        fail << "invalid installation directory " << d << ": " << e.what ();
+        fail << "invalid installation directory " << d << ": " << e;
       }
 
       if (r)
@@ -718,7 +718,7 @@ namespace build2
           }
           catch (const system_error& e)
           {
-            fail << "unable to remove directory " << d << ": " << e.what ();
+            fail << "unable to remove directory " << d << ": " << e;
           }
         }
         else
@@ -748,7 +748,7 @@ namespace build2
           }
           catch (const process_error& e)
           {
-            error << "unable to execute " << args[0] << ": " << e.what ();
+            error << "unable to execute " << args[0] << ": " << e;
 
             if (e.child ())
               exit (1);
@@ -791,7 +791,7 @@ namespace build2
       }
       catch (const system_error& e)
       {
-        fail << "invalid installation path " << f << ": " << e.what ();
+        fail << "invalid installation path " << f << ": " << e;
       }
 
       path relf (relative (f));
@@ -818,7 +818,7 @@ namespace build2
         }
         catch (const system_error& e)
         {
-          fail << "unable to remove file " << f << ": " << e.what ();
+          fail << "unable to remove file " << f << ": " << e;
         }
       }
       else
@@ -847,7 +847,7 @@ namespace build2
         }
         catch (const process_error& e)
         {
-          error << "unable to execute " << args[0] << ": " << e.what ();
+          error << "unable to execute " << args[0] << ": " << e;
 
           if (e.child ())
             exit (1);
diff --git a/build2/parser.cxx b/build2/parser.cxx
index d01b6fe..57a5618 100644
--- a/build2/parser.cxx
+++ b/build2/parser.cxx
@@ -820,7 +820,7 @@ namespace build2
       }
       catch (const io_error& e)
       {
-        fail (l) << "unable to read buildfile " << p << ": " << e.what ();
+        fail (l) << "unable to read buildfile " << p << ": " << e;
       }
     }
 
@@ -956,7 +956,7 @@ namespace build2
       }
       catch (const io_error& e)
       {
-        fail (l) << "unable to read buildfile " << p << ": " << e.what ();
+        fail (l) << "unable to read buildfile " << p << ": " << e;
       }
 
       scope_ = ocs;
@@ -1214,7 +1214,7 @@ namespace build2
           try {iv = to_version (v);}
           catch (const invalid_argument& e)
           {
-            fail (l) << "invalid version '" << v << "': " << e.what () << endf;
+            fail (l) << "invalid version '" << v << "': " << e << endf;
           }
 
           if (iv > BUILD2_VERSION)
@@ -1329,7 +1329,7 @@ namespace build2
 
             take = (k.back () == '!' ? !e : e);
           }
-          catch (const invalid_argument& e) { fail (l) << e.what (); }
+          catch (const invalid_argument& e) { fail (l) << e; }
         }
       }
       else
@@ -1433,7 +1433,7 @@ namespace build2
         return;
       }
     }
-    catch (const invalid_argument& e) { fail (el) << e.what (); }
+    catch (const invalid_argument& e) { fail (el) << e; }
 
     // Being here means things didn't end up well. Parse the description, if
     // any, with expansion. Then fail.
@@ -1798,7 +1798,7 @@ namespace build2
     {
       q = pp ? true : convert<bool> (move (lhs));
     }
-    catch (const invalid_argument& e) { fail (l) << e.what () << endf; }
+    catch (const invalid_argument& e) { fail (l) << e << endf; }
 
     if (!pp)
       pre_parse_ = !q; // Short-circuit middle?
@@ -1852,7 +1852,7 @@ namespace build2
         //
         lhs = convert<bool> (move (rhs));
       }
-      catch (const invalid_argument& e) { fail (l) << e.what (); }
+      catch (const invalid_argument& e) { fail (l) << e; }
     }
 
     pre_parse_ = pp;
@@ -1892,7 +1892,7 @@ namespace build2
         //
         lhs = convert<bool> (move (rhs));
       }
-      catch (const invalid_argument& e) { fail (l) << e.what (); }
+      catch (const invalid_argument& e) { fail (l) << e; }
     }
 
     pre_parse_ = pp;
@@ -2005,7 +2005,7 @@ namespace build2
           //
           v = !convert<bool> (move (v));
         }
-        catch (const invalid_argument& e) { fail (l) << e.what (); }
+        catch (const invalid_argument& e) { fail (l) << e; }
         break;
       }
     default:
diff --git a/build2/pkgconfig/init.cxx b/build2/pkgconfig/init.cxx
index 7149eb6..8d50def 100644
--- a/build2/pkgconfig/init.cxx
+++ b/build2/pkgconfig/init.cxx
@@ -72,7 +72,7 @@ namespace build2
         }
         catch (const process_error& e)
         {
-          fail << "unable to execute " << x << ": " << e.what ();
+          fail << "unable to execute " << x << ": " << e;
         }
       }
 
diff --git a/build2/rule.cxx b/build2/rule.cxx
index 433814e..a9b7c4e 100644
--- a/build2/rule.cxx
+++ b/build2/rule.cxx
@@ -226,7 +226,7 @@ namespace build2
       }
       catch (const system_error& e)
       {
-        fail << "unable to create directory " << d << ": " << e.what ();
+        fail << "unable to create directory " << d << ": " << e;
       }
 
       ts |= target_state::changed;
diff --git a/build2/test/rule.cxx b/build2/test/rule.cxx
index ccbf932..4201f37 100644
--- a/build2/test/rule.cxx
+++ b/build2/test/rule.cxx
@@ -498,7 +498,7 @@ namespace build2
       }
       catch (const process_error& e)
       {
-        error << "unable to execute " << args[0] << ": " << e.what ();
+        error << "unable to execute " << args[0] << ": " << e;
 
         if (e.child ())
           exit (1);
diff --git a/build2/test/script/builtin.cxx b/build2/test/script/builtin.cxx
index 0b99e8f..d00a8a1 100644
--- a/build2/test/script/builtin.cxx
+++ b/build2/test/script/builtin.cxx
@@ -161,7 +161,7 @@ namespace build2
             else
               cerr << "'" << p << "'";
 
-            cerr << ": " << e.what () << endl;
+            cerr << ": " << e << endl;
             throw failed ();
           }
 
@@ -179,7 +179,7 @@ namespace build2
         catch (const io_error& e)
         {
           if (cerr.good ())
-            cerr << "cat: " << e.what () << endl;
+            cerr << "cat: " << e << endl;
         }
         catch (const failed&)
         {
@@ -222,7 +222,7 @@ namespace build2
         }
         catch (const std::exception& e)
         {
-          cerr << "echo: " << e.what () << endl;
+          cerr << "echo: " << e << endl;
         }
 
         cerr.close ();
@@ -338,7 +338,7 @@ namespace build2
             catch (const system_error& e)
             {
               cerr << "mkdir: unable to create directory '" << p << "': "
-                   << e.what () << endl;
+                   << e << endl;
               throw failed ();
             }
           }
@@ -355,7 +355,7 @@ namespace build2
         catch (const io_error& e)
         {
           if (cerr.good ())
-            cerr << "mkdir: " << e.what () << endl;
+            cerr << "mkdir: " << e << endl;
         }
         catch (const failed&)
         {
@@ -478,8 +478,7 @@ namespace build2
             }
             catch (const system_error& e)
             {
-              cerr << "rm: unable to remove '" << p << "': " << e.what ()
-                   << endl;
+              cerr << "rm: unable to remove '" << p << "': " << e << endl;
               throw failed ();
             }
           }
@@ -496,7 +495,7 @@ namespace build2
         catch (const io_error& e)
         {
           if (cerr.good ())
-            cerr << "rm: " << e.what () << endl;
+            cerr << "rm: " << e << endl;
         }
         catch (const failed&)
         {
@@ -578,8 +577,8 @@ namespace build2
                 }
                 catch (const io_error& e)
                 {
-                  cerr << "touch: cannot create file '" << p << "': "
-                       << e.what () << endl;
+                  cerr << "touch: cannot create file '" << p << "': " << e
+                       << endl;
                   throw failed ();
                 }
 
@@ -594,8 +593,8 @@ namespace build2
             }
             catch (const system_error& e)
             {
-              cerr << "touch: cannot create/update '" << p << "': "
-                   << e.what () << endl;
+              cerr << "touch: cannot create/update '" << p << "': " << e
+                   << endl;
               throw failed ();
             }
           }
@@ -612,7 +611,7 @@ namespace build2
         catch (const io_error& e)
         {
           if (cerr.good ())
-            cerr << "touch: " << e.what () << endl;
+            cerr << "touch: " << e << endl;
         }
         catch (const failed&)
         {
diff --git a/build2/test/script/parser.cxx b/build2/test/script/parser.cxx
index f545896..e5f634c 100644
--- a/build2/test/script/parser.cxx
+++ b/build2/test/script/parser.cxx
@@ -3,7 +3,7 @@
 // license   : MIT; see accompanying LICENSE file
 
 #include <sstream>
-#include <cstring> // strstr(), strchr()
+#include <cstring> // strstr()
 
 #include <build2/test/script/parser>
 
@@ -26,20 +26,24 @@ namespace std
   // resembles the following: 'regex_error(error_badrepeat): '. So we skip it.
   //
   static ostream&
-  operator<< (ostream& os, const regex_error& e)
+  operator<< (ostream& o, const regex_error& e)
   {
     const char* d (e.what ());
-    if (strchr (d, ' ') != nullptr)
-    {
+
 #if defined(_MSC_VER) && _MSC_VER <= 1910
-      const char* s (strstr (d, "): "));
-      if (s != nullptr)
-        d = s + 3;
+    const char* rd (strstr (d, "): "));
+    if (rd != nullptr)
+      d = rd + 3;
 #endif
-      os << ": " << d;
-    }
 
-    return os;
+    ostringstream os;
+    os << runtime_error (d); // Purify the description.
+
+    string s (os.str ());
+    if (s.find (' ') != string::npos)
+      o << ": " << s;
+
+    return o;
   }
 }
 
@@ -77,8 +81,7 @@ namespace build2
         }
         catch (const io_error& e)
         {
-          fail << "unable to read testscript " << p << ": " << e.what ()
-               << endf;
+          fail << "unable to read testscript " << p << ": " << e << endf;
         }
       }
 
@@ -1054,8 +1057,7 @@ namespace build2
             }
             catch (const io_error& e)
             {
-              fail (dl) << "unable to read testscript " << p << ": "
-                        << e.what ();
+              fail (dl) << "unable to read testscript " << p << ": " << e;
             }
           }
         };
diff --git a/build2/test/script/runner.cxx b/build2/test/script/runner.cxx
index cbf0de0..64c6e87 100644
--- a/build2/test/script/runner.cxx
+++ b/build2/test/script/runner.cxx
@@ -41,7 +41,7 @@ namespace build2
           // executed let's add the location anyway to ease the
           // troubleshooting. And let's stick to that principle down the road.
           //
-          fail (ll) << "unable to read " << p << ": " << e.what () << endf;
+          fail (ll) << "unable to read " << p << ": " << e << endf;
         }
       }
 
@@ -91,7 +91,7 @@ namespace build2
           }
           catch (const io_error& e)
           {
-            fail (ll) << "unable to read " << p << ": " << e.what ();
+            fail (ll) << "unable to read " << p << ": " << e;
           }
         }
       }
@@ -151,7 +151,7 @@ namespace build2
           }
           catch (const io_error& e)
           {
-            fail (ll) << "unable to write " << opp << ": " << e.what ();
+            fail (ll) << "unable to write " << opp << ": " << e;
           }
 
           auto output_info = [&what, &ll] (diag_record& d,
@@ -203,6 +203,9 @@ namespace build2
                 //
                 // ...: Invalid data.\r\r\n
                 //
+                // Note that our custom operator<<(ostream&, const exception&)
+                // removes this junk.
+                //
                 while (!s.empty () && s.back () == '\r')
                   s.pop_back ();
 
@@ -211,7 +214,7 @@ namespace build2
             }
             catch (const io_error& e)
             {
-              fail (ll) << "unable to read " << op << ": " << e.what ();
+              fail (ll) << "unable to read " << op << ": " << e;
             }
 
             if (regex_match (ls, rd.regex.regex)) // Doesn't throw.
@@ -263,7 +266,7 @@ namespace build2
               }
               catch (const io_error& e)
               {
-                fail (ll) << "unable to write " << ep << ": " << e.what ();
+                fail (ll) << "unable to write " << ep << ": " << e;
               }
 
               // Diff utility prints the differences to stdout. But for the
@@ -293,7 +296,7 @@ namespace build2
             }
             catch (const process_error& e)
             {
-              error (ll) << "unable to execute " << pp << ": " << e.what ();
+              error (ll) << "unable to execute " << pp << ": " << e;
 
               if (e.child ())
                 exit (1);
@@ -506,7 +509,7 @@ namespace build2
           }
           catch (const io_error& e)
           {
-            fail (ll) << "unable to read " << isp << ": " << e.what ();
+            fail (ll) << "unable to read " << isp << ": " << e;
           }
         };
 
@@ -521,7 +524,7 @@ namespace build2
             }
             catch (const io_error& e)
             {
-              fail (ll) << "unable to duplicate stdin: " << e.what ();
+              fail (ll) << "unable to duplicate stdin: " << e;
             }
 
             break;
@@ -556,7 +559,7 @@ namespace build2
             }
             catch (const io_error& e)
             {
-              fail (ll) << "unable to write to null device: " << e.what ();
+              fail (ll) << "unable to write to null device: " << e;
             }
 
             break;
@@ -587,7 +590,7 @@ namespace build2
             }
             catch (const io_error& e)
             {
-              fail (ll) << "unable to write " << isp << ": " << e.what ();
+              fail (ll) << "unable to write " << isp << ": " << e;
             }
 
             open_stdin ();
@@ -639,8 +642,7 @@ namespace build2
               }
               catch (const io_error& e)
               {
-                fail (ll) << "unable to duplicate " << what << ": "
-                          << e.what ();
+                fail (ll) << "unable to duplicate " << what << ": " << e;
               }
 
               return dfd;
@@ -658,7 +660,7 @@ namespace build2
               }
               catch (const io_error& e)
               {
-                fail (ll) << "unable to write to null device: " << e.what ();
+                fail (ll) << "unable to write to null device: " << e;
               }
 
               return -2;
@@ -699,7 +701,7 @@ namespace build2
           }
           catch (const io_error& e)
           {
-            fail (ll) << "unable to write " << p << ": " << e.what ();
+            fail (ll) << "unable to write " << p << ": " << e;
           }
 
           return fd.get ();
@@ -729,7 +731,7 @@ namespace build2
           catch (const io_error& e)
           {
             fail (ll) << "unable to duplicate " << (mo ? "stderr" : "stdout")
-                      << ": " << e.what ();
+                      << ": " << e;
           }
         }
 
@@ -750,7 +752,7 @@ namespace build2
           catch (const system_error& e)
           {
             fail (ll) << "unable to execute " << c.program << " builtin: "
-                      << e.what ();
+                      << e;
           }
         }
         else
@@ -788,7 +790,7 @@ namespace build2
           }
           catch (const process_error& e)
           {
-            error (ll) << "unable to execute " << pp << ": " << e.what ();
+            error (ll) << "unable to execute " << pp << ": " << e;
 
             if (e.child ())
               std::exit (1);
diff --git a/build2/utility.cxx b/build2/utility.cxx
index cf7e867..76d3367 100644
--- a/build2/utility.cxx
+++ b/build2/utility.cxx
@@ -160,7 +160,7 @@ namespace build2
   }
   catch (const process_error& e)
   {
-    fail << "unable to execute " << args0 << ": " << e.what () << endf;
+    fail << "unable to execute " << args0 << ": " << e << endf;
   }
 
   process_path
@@ -171,7 +171,7 @@ namespace build2
   }
   catch (const process_error& e)
   {
-    fail << "unable to execute " << f << ": " << e.what () << endf;
+    fail << "unable to execute " << f << ": " << e << endf;
   }
 
   process
@@ -192,11 +192,11 @@ namespace build2
       {
         // Note: run_finish() expects this exact message.
         //
-        cerr << "unable to execute " << args[0] << ": " << e.what () << endl;
+        cerr << "unable to execute " << args[0] << ": " << e << endl;
         exit (1);
       }
       else
-        fail << "unable to execute " << args[0] << ": " << e.what () << endf;
+        fail << "unable to execute " << args[0] << ": " << e << endf;
     }
   }
 
@@ -225,7 +225,7 @@ namespace build2
   }
   catch (const process_error& e)
   {
-    fail << "unable to execute " << args[0] << ": " << e.what () << endf;
+    fail << "unable to execute " << args[0] << ": " << e << endf;
   }
 
   const string empty_string;