NMake,JOM,Borland: Avoid case collisions for test_prep targets

These make tools match target names case-insensitively, so generating a
separate rule for tests whose names differ only in case produces a
duplicate rule, and a test named e.g. "All" collides with the
"test_prep/all" rule and forms a dependency cycle.

Key the "test_prep/" target map on the lowercased name when the
generator matches target names case-insensitively, keeping the
first spelling seen for the user-facing target name.

Amends commit 503bdb9777 (Makefile: Generate test_prep targets for
CMAKE_TEST_BUILD_DEPENDS, 2026-06-24).

Source/cmGlobalBorlandMakefileGenerator.h

@@ -56,6 +56,8 @@ public:
 
   bool IsGNUMakeJobServerAware() const override { return false; }
 
+  bool TargetNamesAreCaseInsensitive() const override { return true; }
+
   std::string GetShortBinaryOutputDir() const override;
 
 protected:

Source/cmGlobalJOMMakefileGenerator.h

@@ -49,6 +49,8 @@ public:
 
   bool IsGNUMakeJobServerAware() const override { return false; }
 
+  bool TargetNamesAreCaseInsensitive() const override { return true; }
+
 protected:
   std::vector<GeneratedMakeCommand> GenerateBuildCommand(
     std::string const& makeProgram, std::string const& projectName,

Source/cmGlobalNMakeMakefileGenerator.h

@@ -56,6 +56,8 @@ public:
 
   bool IsGNUMakeJobServerAware() const override { return false; }
 
+  bool TargetNamesAreCaseInsensitive() const override { return true; }
+
 protected:
   std::vector<GeneratedMakeCommand> GenerateBuildCommand(
     std::string const& makeProgram, std::string const& projectName,

Source/cmGlobalUnixMakefileGenerator3.cxx

@@ -1101,7 +1101,12 @@ void cmGlobalUnixMakefileGenerator3::ComputeTestPrepTargets()
 cmGlobalUnixMakefileGenerator3::TestPrepTarget&
 cmGlobalUnixMakefileGenerator3::GetTestPrepTarget(std::string const& name)
 {
-  TestPrepTarget& testPrepTarget = this->TestPrepTargets[name];
+  // Merge targets whose names differ only in case where the make tool does
+  // not distinguish them. Keep the first spelling for the user-facing name.
+  TestPrepTarget& testPrepTarget =
+    this->TestPrepTargets[this->TargetNamesAreCaseInsensitive()
+                            ? cmSystemTools::LowerCase(name)
+                            : name];
   if (testPrepTarget.Name.empty()) {
     testPrepTarget.Name = name;
   }
@@ -1160,6 +1165,12 @@ void cmGlobalUnixMakefileGenerator3::WriteTestPrepRules(
   std::vector<std::string> no_commands;
   std::vector<std::string> allDeps;
   for (auto const& entry : this->TestPrepTargets) {
+    // A test whose target name matches "test_prep/all" is prepared by the
+    // rule for all tests.
+    if (entry.first == "test_prep/all") {
+      cm::append(allDeps, entry.second.Rules);
+      continue;
+    }
     std::vector<std::string> depends = entry.second.Rules;
     if (depends.empty() && !this->EmptyRuleHackDepends.empty()) {
       depends.push_back(this->EmptyRuleHackDepends);
@@ -1196,6 +1207,10 @@ void cmGlobalUnixMakefileGenerator3::WriteTestPrepConvenienceRules(
   ruleFileStream << "# Convenience rules to build test dependencies.\n\n";
 
   for (auto const& entry : this->TestPrepTargets) {
+    // The "test_prep/all" rule is written below.
+    if (entry.first == "test_prep/all") {
+      continue;
+    }
     depends.clear();
     if (regenerate) {
       depends.emplace_back("cmake_check_build_system");

Source/cmGlobalUnixMakefileGenerator3.h

@@ -121,6 +121,13 @@ public:
 
   bool IsGNUMakeJobServerAware() const override { return true; }
 
+  /**
+   * Utilized to determine if the make tool matches target names
+   * case-insensitively, so that generated target names may not differ
+   * only in case.
+   */
+  virtual bool TargetNamesAreCaseInsensitive() const { return false; }
+
   /**
    * Generate the all required files for building this project/tree. This
    * basically creates a series of LocalGenerators for each directory and

Tests/RunCMake/TestDependency/ON-case-build-check.cmake

@@ -0,0 +1,4 @@
+if(NOT EXISTS "${RunCMake_TEST_BINARY_DIR}/${dependency}_case_dependency-built.txt")
+  set(RunCMake_TEST_FAILED
+    "test_prep did not build ${dependency}_case_dependency.")
+endif()

Tests/RunCMake/TestDependency/ON-case.cmake

@@ -0,0 +1,20 @@
+cmake_minimum_required(VERSION 4.3)
+set(CMAKE_TEST_BUILD_DEPENDS ON)
+
+project(TestDependencyCase NONE)
+
+enable_testing()
+
+# Test names that differ only in case each get a working test_prep target,
+# even where the build tool's target names are case-insensitive.
+foreach(case IN ITEMS "Mixed;upper" "mixed;lower" "All;all")
+  list(GET case 0 test)
+  list(GET case 1 dependency)
+  add_custom_target(${dependency}_case_dependency
+    COMMAND ${CMAKE_COMMAND} -E touch ${dependency}_case_dependency-built.txt)
+  set_property(TARGET ${dependency}_case_dependency
+    PROPERTY EXCLUDE_FROM_ALL TRUE)
+  add_test(NAME ${test}
+    COMMAND ${CMAKE_COMMAND} -E true
+    BUILD_DEPENDS ${dependency}_case_dependency)
+endforeach()

Tests/RunCMake/TestDependency/RunCMakeTest.cmake

@@ -201,6 +201,21 @@ if(RunCMake_GENERATOR MATCHES "Ninja|FASTBuild|Makefiles")
         -R "^ImportedTest$")
     endblock()
 
+    # Test names that differ only in case each get a working test_prep target.
+    block()
+      set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/ON-case-build)
+      run_cmake(ON-case)
+      set(RunCMake_TEST_NO_CLEAN 1)
+      foreach(case IN ITEMS "Mixed;upper" "mixed;lower" "All;all")
+        list(GET case 0 test)
+        list(GET case 1 dependency)
+        set(RunCMake-check-file ON-case-build-check.cmake)
+        run_cmake_command(ON-case-${dependency}-build
+          ${CMAKE_COMMAND} --build . ${TestDependency_BUILD_CONFIG_ARG}
+          --target test_prep/${test})
+      endforeach()
+    endblock()
+
     # Exceptions for Makefile generator
     if(RunCMake_GENERATOR MATCHES Makefiles)
       # Diagnostics specific to the Makefile generators.