Merge #19131: refactor: Fix unreachable code in init arg checks

eea8114657 build: Enable unreachable-code-loop-increment (Jonathan Schoeller)
d15db4b1fc refactor: Fix unreachable code in init arg checks (Jonathan Schoeller)

Pull request description:

  Closes: #19017

  In #19015 it's been suggested that we add some new compiler warnings to our build. Some of these, such as `-Wunreachable-code-loop-increment`, generate warnings. We'll likely want to fix these up if we're going to turn these warnings on.

  ```shell
  init.cpp:969:5: warning: loop will run at most once (loop increment never executed) [-Wunreachable-code-loop-increment]
       for (const auto& arg : gArgs.GetUnsuitableSectionOnlyArgs()) {
       ^~~
   1 warning generated.
   ```
   aa8d76806c/src/init.cpp (L968-L972)

  To fix this, collect all errors, and output them in a single error message after the loop completes. This resolves the unreachable code warning, and avoids popup hell that could result from outputting a seperate message for each error or warning one by one.

ACKs for top commit:
  laanwj:
    Code review ACK eea8114657
  hebasto:
    re-ACK eea8114657, only suggested changes applied since the [previous](https://github.com/bitcoin/bitcoin/pull/19131#pullrequestreview-421772387) review.

Tree-SHA512: 2aa3ceb7fab581b6ba2580900668388d8eba1c3001c8ff9c11c1f4a9a10fbc37f30e590249862676858446e3f4950140a252953ba1643ba3bfd772f8eae20583

configure.ac

@@ -391,6 +391,7 @@ if test "x$enable_werror" = "xyes"; then
   dnl https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78010
   AX_CHECK_COMPILE_FLAG([-Werror=suggest-override],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=suggest-override"],,[[$CXXFLAG_WERROR]],
                         [AC_LANG_SOURCE([[struct A { virtual void f(); }; struct B : A { void f() final; };]])])
+  AX_CHECK_COMPILE_FLAG([-Werror=unreachable-code-loop-increment],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=unreachable-code-loop-increment"],,[[$CXXFLAG_WERROR]])
 fi
 
 if test "x$CXXFLAGS_overridden" = "xno"; then
@@ -410,6 +411,7 @@ if test "x$CXXFLAGS_overridden" = "xno"; then
   AX_CHECK_COMPILE_FLAG([-Wsign-compare],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wsign-compare"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Wsuggest-override],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wsuggest-override"],,[[$CXXFLAG_WERROR]],
                         [AC_LANG_SOURCE([[struct A { virtual void f(); }; struct B : A { void f() final; };]])])
+  AX_CHECK_COMPILE_FLAG([-Wunreachable-code-loop-increment],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wunreachable-code-loop-increment"],,[[$CXXFLAG_WERROR]])
 
   dnl Some compilers (gcc) ignore unknown -Wno-* options, but warn about all
   dnl unknown options if any other warning is produced. Test the -Wfoo case, and

src/init.cpp

@@ -964,17 +964,27 @@ bool AppInitParameterInteraction()
 
     // also see: InitParameterInteraction()
 
-    // Warn if network-specific options (-addnode, -connect, etc) are
+    // Error if network-specific options (-addnode, -connect, etc) are
     // specified in default section of config file, but not overridden
     // on the command line or in this network's section of the config file.
     std::string network = gArgs.GetChainName();
+    bilingual_str errors;
     for (const auto& arg : gArgs.GetUnsuitableSectionOnlyArgs()) {
-        return InitError(strprintf(_("Config setting for %s only applied on %s network when in [%s] section."), arg, network, network));
+        errors += strprintf(_("Config setting for %s only applied on %s network when in [%s] section.") + Untranslated("\n"), arg, network, network);
+    }
+
+    if (!errors.empty()) {
+        return InitError(errors);
     }
 
     // Warn if unrecognized section name are present in the config file.
+    bilingual_str warnings;
     for (const auto& section : gArgs.GetUnrecognizedSections()) {
-        InitWarning(strprintf(Untranslated("%s:%i ") + _("Section [%s] is not recognized."), section.m_file, section.m_line, section.m_name));
+        warnings += strprintf(Untranslated("%s:%i ") + _("Section [%s] is not recognized.") + Untranslated("\n"), section.m_file, section.m_line, section.m_name);
+    }
+
+    if (!warnings.empty()) {
+        InitWarning(warnings);
     }
 
     if (!fs::is_directory(GetBlocksDir())) {

src/util/translation.h

@@ -23,6 +23,11 @@ struct bilingual_str {
         translated += rhs.translated;
         return *this;
     }
+
+    bool empty() const
+    {
+        return original.empty();
+    }
 };
 
 inline bilingual_str operator+(bilingual_str lhs, const bilingual_str& rhs)

test/functional/feature_config_args.py

@@ -71,7 +71,7 @@ class ConfArgsTest(BitcoinTestFramework):
         with open(inc_conf_file2_path, 'w', encoding='utf-8') as conf:
             conf.write('[testnet]\n')
         self.restart_node(0)
-        self.nodes[0].stop_node(expected_stderr='Warning: ' + inc_conf_file_path + ':1 Section [testnot] is not recognized.' + os.linesep + 'Warning: ' + inc_conf_file2_path + ':1 Section [testnet] is not recognized.')
+        self.nodes[0].stop_node(expected_stderr='Warning: ' + inc_conf_file_path + ':1 Section [testnot] is not recognized.' + os.linesep + inc_conf_file2_path + ':1 Section [testnet] is not recognized.')
 
         with open(inc_conf_file_path, 'w', encoding='utf-8') as conf:
             conf.write('')  # clear