[clang-tidy] Ignore ExprWithCleanups when looking for else-after-throw

[malcolm.parsons]

Summary

The readability-else-after-return check was not warning about
an else after a throw of an exception that had arguments that needed
to be cleaned up.

[lebedev.ri]

How about also matching on call to functions with no-return attribute?
i.e.

[[noreturn]] my_die();
void do_stuff();

void fn(int x) {
  if(!x)
    my_die();
  else // <- since `my_die()` will never return, `else` is not really needed.
    do_stuff();
}

[malcolm.parsons]

In D40505#936170, @lebedev.ri wrote:

How about also matching on call to functions with no-return attribute?

Great idea!

But I'll keep this patch for just the throw bugfix.

[aaron.ballman]

LGTM with a minor formatting nit.

test/clang-tidy/readability-else-after-return.cpp

7

Indentation is incorrect here.

[malcolm.parsons]

clang-format

clang-tidy/readability/ElseAfterReturnCheck.cpp

 
 namespace clang {
 namespace tidy {
 namespace readability {
 
 void ElseAfterReturnCheck::registerMatchers(MatchFinder *Finder) {
   const auto ControlFlowInterruptorMatcher =
       stmt(anyOf(returnStmt().bind("return"), continueStmt().bind("continue"),
-                 breakStmt().bind("break"), cxxThrowExpr().bind("throw")));
+                 breakStmt().bind("break"),
+                 expr(ignoringImplicit(cxxThrowExpr().bind("throw")))));
   Finder->addMatcher(
       compoundStmt(forEach(
           ifStmt(hasThen(stmt(
                      anyOf(ControlFlowInterruptorMatcher,
                            compoundStmt(has(ControlFlowInterruptorMatcher))))),
                  hasElse(stmt().bind("else")))
               .bind("if"))),
       this);

test/clang-tidy/readability-else-after-return.cpp

 // RUN: %check_clang_tidy %s readability-else-after-return %t -- -- -std=c++11 -fexceptions
 
+namespace std {
+struct string {
+  string(const char *);
+  ~string();
+};
+} // namespace std
+
+struct my_exception {
+  my_exception(const std::string &s);
+};
+
 void f(int a) {
   if (a > 0)
     return;
   else // comment-0
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not use 'else' after 'return'
   // CHECK-FIXES: {{^}}  // comment-0
     return;
 
for (unsigned x = 0; x < 42; ++x) {
     }
     if (x) {
       throw 42;
     } else { // comment-9
     // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: do not use 'else' after 'throw'
     // CHECK-FIXES: {{^}}    } // comment-9
       x++;
     }
+    if (x) {
+      throw my_exception("foo");
+    } else { // comment-10
+    // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: do not use 'else' after 'throw'
+    // CHECK-FIXES: {{^}}    } // comment-10
+      x++;
+    }
   }
 }