Linking: Preserve nested LINKER: prefixes as written

Previously LINKER:,-Xlinker and -Wl, options nested inside LINKER:
prefixes would be transformed to separate prefixed options.
This is confusing and undocumented behavior, instead preserve these
as written.

Fixes: #26298

Source/cmGeneratorTarget_Options.cxx

@@ -7,6 +7,7 @@
 #include "cmConfigure.h"
 
 #include <algorithm>
+#include <iterator>
 #include <map>
 #include <memory>
 #include <string>
@@ -91,10 +92,16 @@ void processOptions(cmGeneratorTarget const* tgt,
   }
 }
 
+enum class NestedLinkerFlags
+{
+  PreserveAsSpelled,
+  Normalize,
+};
+
 std::vector<BT<std::string>> wrapOptions(
   std::vector<std::string>& options, const cmListFileBacktrace& bt,
   const std::vector<std::string>& wrapperFlag, const std::string& wrapperSep,
-  bool concatFlagAndArgs)
+  bool concatFlagAndArgs, NestedLinkerFlags nestedLinkerFlags)
 {
   std::vector<BT<std::string>> result;
 
@@ -148,6 +155,11 @@ std::vector<BT<std::string>> wrapOptions(
     }
   };
 
+  if (nestedLinkerFlags == NestedLinkerFlags::PreserveAsSpelled) {
+    insertWrapped(options);
+    return result;
+  }
+
   for (std::vector<std::string>::size_type index = 0; index < options.size();
        index++) {
     if (cmHasLiteralPrefix(options[index], "LINKER:")) {
@@ -488,8 +500,9 @@ std::vector<BT<std::string>> cmGeneratorTarget::GetLinkOptions(
         // host link options must be wrapped
         std::vector<std::string> options;
         cmSystemTools::ParseUnixCommandLine(it->Value.c_str(), options);
-        auto hostOptions = wrapOptions(options, it->Backtrace, wrapperFlag,
-                                       wrapperSep, concatFlagAndArgs);
+        auto hostOptions =
+          wrapOptions(options, it->Backtrace, wrapperFlag, wrapperSep,
+                      concatFlagAndArgs, NestedLinkerFlags::Normalize);
         it = result.erase(it);
         // some compilers (like gcc 4.8 or Intel 19.0 or XLC 16) do not respect
         // C++11 standard: 'std::vector::insert()' do not returns an iterator,
@@ -538,12 +551,11 @@ std::vector<BT<std::string>>& cmGeneratorTarget::ResolveLinkerWrapper(
   const std::string SHELL{ "SHELL:" };
   const std::string LINKER_SHELL = LINKER + SHELL;
 
-  std::vector<BT<std::string>>::iterator entry;
-  while ((entry = std::find_if(result.begin(), result.end(),
-                               [&LINKER](BT<std::string> const& item) -> bool {
-                                 return item.Value.compare(0, LINKER.length(),
-                                                           LINKER) == 0;
-                               })) != result.end()) {
+  for (auto entry = result.begin(); entry != result.end(); ++entry) {
+    if (entry->Value.compare(0, LINKER.length(), LINKER) != 0) {
+      continue;
+    }
+
     std::string value = std::move(entry->Value);
     cmListFileBacktrace bt = std::move(entry->Backtrace);
     entry = result.erase(entry);
@@ -573,15 +585,19 @@ std::vector<BT<std::string>>& cmGeneratorTarget::ResolveLinkerWrapper(
       return result;
     }
 
-    std::vector<BT<std::string>> options = wrapOptions(
-      linkerOptions, bt, wrapperFlag, wrapperSep, concatFlagAndArgs);
+    // Very old versions of the C++ standard library return void for insert, so
+    // can't use it to get the new iterator
+    const auto index = entry - result.begin();
+    std::vector<BT<std::string>> options =
+      wrapOptions(linkerOptions, bt, wrapperFlag, wrapperSep,
+                  concatFlagAndArgs, NestedLinkerFlags::PreserveAsSpelled);
     if (joinItems) {
-      result.insert(entry,
-                    cmJoin(cmRange<decltype(options.cbegin())>(
-                             options.cbegin(), options.cend()),
-                           " "_s));
+      result.insert(
+        entry, cmJoin(cmMakeRange(options.begin(), options.end()), " "_s));
+      entry = std::next(result.begin(), index);
     } else {
       result.insert(entry, options.begin(), options.end());
+      entry = std::next(result.begin(), index + options.size() - 1);
     }
   }
   return result;

Tests/RunCMake/target_link_options/LINKER_expansion-LINKER-check.cmake

@@ -1,2 +1,3 @@
 
+set(reference_file "LINKER.txt")
 include ("${CMAKE_CURRENT_LIST_DIR}/LINKER_expansion-validation.cmake")

Tests/RunCMake/target_link_options/LINKER_expansion-LINKER_NESTED-check.cmake

@@ -0,0 +1,4 @@
+
+set(reference_file "LINKER_NESTED.txt")
+set(linker_prefix_expected YES)
+include ("${CMAKE_CURRENT_LIST_DIR}/LINKER_expansion-validation.cmake")

Tests/RunCMake/target_link_options/LINKER_expansion-LINKER_NESTED_SHELL-check.cmake

@@ -0,0 +1,4 @@
+
+set(reference_file "LINKER_NESTED_SHELL.txt")
+set(linker_prefix_expected YES)
+include ("${CMAKE_CURRENT_LIST_DIR}/LINKER_expansion-validation.cmake")

Tests/RunCMake/target_link_options/LINKER_expansion-LINKER_SHELL-check.cmake

@@ -1,2 +1,3 @@
 
+set(reference_file "LINKER.txt")
 include ("${CMAKE_CURRENT_LIST_DIR}/LINKER_expansion-validation.cmake")

Tests/RunCMake/target_link_options/LINKER_expansion-validation.cmake

@@ -1,14 +1,14 @@
 
-if (actual_stdout MATCHES "LINKER:")
+if (actual_stdout MATCHES "LINKER:" AND NOT linker_prefix_expected)
   set (RunCMake_TEST_FAILED "LINKER: prefix was not expanded.")
   return()
 endif()
 
-if (NOT EXISTS "${RunCMake_TEST_BINARY_DIR}/LINKER.txt")
-  set (RunCMake_TEST_FAILED "${RunCMake_TEST_BINARY_DIR}/LINKER.txt: Reference file not found.")
+if (NOT EXISTS "${RunCMake_TEST_BINARY_DIR}/${reference_file}")
+  set (RunCMake_TEST_FAILED "${RunCMake_TEST_BINARY_DIR}/${reference_file}: Reference file not found.")
   return()
 endif()
-file(READ "${RunCMake_TEST_BINARY_DIR}/LINKER.txt" linker_flag)
+file(READ "${RunCMake_TEST_BINARY_DIR}/${reference_file}" linker_flag)
 
 if (NOT actual_stdout MATCHES "${linker_flag}")
   set (RunCMake_TEST_FAILED "LINKER: was not expanded correctly.")

Tests/RunCMake/target_link_options/LINKER_expansion.cmake

@@ -31,6 +31,14 @@ target_link_options(linker PRIVATE "LINKER:-foo,bar")
 add_test_library(linker_shell)
 target_link_options(linker_shell PRIVATE "LINKER:SHELL:-foo bar")
 
+# Nested LINKER: prefixes should be preserved as written, only the outermost LINKER: prefix removed
+add_test_library(linker_nested)
+target_link_options(linker_nested PRIVATE "LINKER:LINKER:-foo,-Xlinker=bar,-Xlinker,--baz,-Wl,/qux")
+
+# Same with LINKER:SHELL:
+add_test_library(linker_nested_shell SHARED LinkOptionsLib.c)
+target_link_options(linker_nested_shell PRIVATE "LINKER:SHELL:LINKER:-foo -Xlinker=bar -Xlinker --baz -Wl,/qux")
+
 # generate reference for LINKER flag
 if (CMAKE_C_LINKER_WRAPPER_FLAG)
   set(linker_flag ${CMAKE_C_LINKER_WRAPPER_FLAG})
@@ -43,12 +51,22 @@ if (CMAKE_C_LINKER_WRAPPER_FLAG)
   list (JOIN linker_flag " " linker_flag)
   if (CMAKE_C_LINKER_WRAPPER_FLAG_SEP)
     set(linker_sep "${CMAKE_C_LINKER_WRAPPER_FLAG_SEP}")
+
+    set(linker_flag_nested       "${linker_flag}${linker_space}LINKER:-foo${linker_sep}-Xlinker=bar${linker_sep}-Xlinker${linker_sep}--baz${linker_sep}-Wl${linker_sep}/qux")
+    set(linker_flag_nested_shell "${linker_flag}${linker_space}LINKER:-foo${linker_sep}-Xlinker=bar${linker_sep}-Xlinker${linker_sep}--baz${linker_sep}-Wl,/qux")
     string (APPEND  linker_flag "${linker_space}" "-foo${linker_sep}bar")
   else()
     set(linker_prefix "${linker_flag}${linker_space}")
+
+    set(linker_flag_nested       "${linker_prefix}LINKER:-foo ${linker_prefix}-Xlinker=bar ${linker_prefix}-Xlinker ${linker_prefix}--baz ${linker_prefix}-Wl ${linker_prefix}/qux")
+    set(linker_flag_nested_shell "${linker_prefix}LINKER:-foo ${linker_prefix}-Xlinker=bar ${linker_prefix}-Xlinker ${linker_prefix}--baz ${linker_prefix}-Wl,/qux")
     set (linker_flag "${linker_prefix}-foo ${linker_prefix}bar")
   endif()
 else()
+  set(linker_flag_nested       "LINKER:-foo -Xlinker=bar -Xlinker --baz -Wl /qux")
+  set(linker_flag_nested_shell "LINKER:-foo -Xlinker=bar -Xlinker --baz -Wl,/qux")
   set(linker_flag "-foo bar")
 endif()
 file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/LINKER.txt" "${linker_flag}")
+file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/LINKER_NESTED.txt" "${linker_flag_nested}")
+file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/LINKER_NESTED_SHELL.txt" "${linker_flag_nested_shell}")

Tests/RunCMake/target_link_options/RunCMakeTest.cmake

@@ -76,6 +76,8 @@ if(RunCMake_GENERATOR MATCHES "(Ninja|Makefile)")
 
   run_cmake_target(LINKER_expansion LINKER linker)
   run_cmake_target(LINKER_expansion LINKER_SHELL linker_shell)
+  run_cmake_target(LINKER_expansion LINKER_NESTED linker_nested)
+  run_cmake_target(LINKER_expansion LINKER_NESTED_SHELL linker_nested_shell)
 endif()
 
 run_cmake(empty_keyword_args)