PCH: Use the target's PREFIX for building the pdb file name

Also copy the REUSE_FROM pdb file only if the file is newer than the
existing one.

Fixes: #19731
Fixes: #20068

Source/cmLocalGenerator.cxx

@@ -2381,9 +2381,25 @@ void cmLocalGenerator::AddPchDependencies(cmGeneratorTarget* target)
                 target->GetLocalGenerator()->GetCurrentBinaryDirectory(), "/",
                 target->GetName(), ".dir/${PDB_PREFIX}");
 
-              file << "if (EXISTS \"" << from_file << "\")\n";
+              const std::string to_file =
+                cmStrCat(to_dir, pchReuseFrom, extension);
+
+              std::string dest_file = to_file;
+
+              const std::string prefix = target->GetSafeProperty("PREFIX");
+              if (!prefix.empty()) {
+                dest_file = cmStrCat(to_dir, prefix, pchReuseFrom, extension);
+              }
+
+              file << "if (EXISTS \"" << from_file << "\" AND \"" << from_file
+                   << "\" IS_NEWER_THAN \"" << dest_file << "\")\n";
               file << "  file(COPY \"" << from_file << "\""
                    << " DESTINATION \"" << to_dir << "\")\n";
+              if (!prefix.empty()) {
+                file << "  file(REMOVE \"" << dest_file << "\")\n";
+                file << "  file(RENAME \"" << to_file << "\" \"" << dest_file
+                     << "\")\n";
+              }
               file << "endif()\n";
             }
 

Tests/RunCMake/PrecompileHeaders/PchReuseFromPrefixed-build-stderr.txt

@@ -0,0 +1,2 @@
+^(|Warning #670: precompiled header file [^
+]* was not generated in this directory)$

Tests/RunCMake/PrecompileHeaders/PchReuseFromPrefixed.cmake

@@ -0,0 +1,29 @@
+cmake_minimum_required(VERSION 3.15)
+project(PchReuseFromPrefixed C)
+
+if(CMAKE_C_COMPILE_OPTIONS_USE_PCH)
+  add_definitions(-DHAVE_PCH_SUPPORT)
+endif()
+
+add_library(empty empty.c)
+target_precompile_headers(empty PRIVATE
+  <stdio.h>
+  <string.h>
+)
+target_include_directories(empty PUBLIC include)
+
+add_library(foo foo.c)
+target_include_directories(foo PUBLIC include)
+target_precompile_headers(foo REUSE_FROM empty)
+
+# Visual Studio 2017 and greater
+if (NOT (CMAKE_C_COMPILER_ID STREQUAL "MSVC" AND CMAKE_C_COMPILER_VERSION VERSION_LESS_EQUAL 19.10))
+  set_target_properties(foo PROPERTIES PREFIX "lib" IMPORT_PREFIX "lib")
+endif()
+
+add_executable(foobar foobar.c)
+target_link_libraries(foobar foo )
+set_target_properties(foobar PROPERTIES PRECOMPILE_HEADERS_REUSE_FROM empty)
+
+enable_testing()
+add_test(NAME foobar COMMAND foobar)

Tests/RunCMake/PrecompileHeaders/RunCMakeTest.cmake

@@ -17,5 +17,6 @@ run_test(PchInterface)
 run_cmake(PchPrologueEpilogue)
 run_test(SkipPrecompileHeaders)
 run_test(PchReuseFrom)
+run_test(PchReuseFromPrefixed)
 run_test(PchReuseFromSubdir)
 run_cmake(PchMultilanguage)