[gcc r15-8941] cobol: Replace quadratic loop removing std::set elements

[James K. Lowden via Gcc-cvs]

https://gcc.gnu.org/g:57d711ba58f8a69dce22b2a543d8e6c668680865

commit r15-8941-g57d711ba58f8a69dce22b2a543d8e6c668680865
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Wed Mar 19 20:33:36 2025 +0000

    cobol: Replace quadratic loop removing std::set elements
    
    There's no need to keep using std::find_if from the beginning of the
    container after every removal, just update the iterator after erasing an
    element.
    
    This is how C++20 std::erase_if is implemented.
    
    gcc/cobol/ChangeLog:
    
            * except.cc (cbl_enabled_exceptions_t::turn_on_off): Replace
            quadratic loop with a single pass.

Diff:
---
 gcc/cobol/except.cc | 32 ++++++++++++++------------------
 1 file changed, 14 insertions(+), 18 deletions(-)

diff --git a/gcc/cobol/except.cc b/gcc/cobol/except.cc
index ba49f78d897f..1485a337ab93 100644
--- a/gcc/cobol/except.cc
+++ b/gcc/cobol/except.cc
@@ -115,31 +115,27 @@ cbl_enabled_exceptions_t::turn_on_off( bool enabled,
     return true;
   }
 
-  /*
-   * std::remove_if cannot be used with std::set because its elements are 
const.
-   * std::set::erase_if became available only in C++20.
-   */
+  // std::set::erase_if became available only in C++20.
   if( enabled ) { // remove any disabled
     if( files.empty() ) {
       auto p = begin();
-      while( end() != (p = std::find_if( begin(), end(),
-                                         [ec = type]( const auto& elem ) {
-                                           return
-                                             !elem.enabled &&
-                                             ec_cmp(ec, elem.ec); } )) ) {
-        erase(p);
+      while( p != end() ) {
+       if( !p->enabled && ec_cmp(type, p->ec) ) {
+         p = erase(p);
+       } else {
+         ++p;
+       }
       }
     } else {
       for( size_t file: files ) {
         auto p = begin();
-        while( end() != (p = std::find_if( begin(), end(),
-                                           [ec = type, file]( const auto& elem 
) {
-                                             return
-                                               !elem.enabled &&
-                                               file == elem.file &&
-                                               ec_cmp(ec, elem.ec); } )) ) {
-          erase(p);
-        }
+        while( p != end() ) {
+         if( !p->enabled && file == p->file && ec_cmp(type, p->ec) ) {
+           p = erase(p);
+         } else {
+           ++p;
+         }
+       }
       }
     }
     auto elem = cbl_enabled_exception_t(enabled, location, type);