Merge topic 'set-ENV-empty'

aa5711490f set: Explicitly unset empty environment variables on Windows
723a83d8cd set: Factor out helper to set environment variables
20761cf349 set: Add test cases for setting ENV{VAR} to empty
a878d1c490 Tests: Unset the PATH environment variable more explicitly where needed

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Merge-request: !11290

Source/cmSetCommand.cxx

@@ -21,6 +21,21 @@
 #include "cmSystemTools.h"
 #include "cmValue.h"
 
+namespace {
+void setENV(std::string const& var, cm::string_view val)
+{
+#ifdef _WIN32
+  if (val.empty()) {
+    // FIXME(#27285): On Windows, PutEnv previously treated empty as unset.
+    // KWSys was fixed, but we need to retain the behavior for compatibility.
+    cmSystemTools::UnPutEnv(var);
+    return;
+  }
+#endif
+  cmSystemTools::PutEnv(cmStrCat(var, '=', val));
+}
+}
+
 // cmSetCommand
 bool cmSetCommand(std::vector<std::string> const& args,
                   cmExecutionStatus& status)
@@ -35,7 +50,6 @@ bool cmSetCommand(std::vector<std::string> const& args,
   if (cmHasLiteralPrefix(variable, "ENV{") && variable.size() > 5) {
     // what is the variable name
     auto const& varName = variable.substr(4, variable.size() - 5);
-    std::string putEnvArg = varName + "=";
 
     // what is the current value if any
     std::string currValue;
@@ -45,8 +59,7 @@ bool cmSetCommand(std::vector<std::string> const& args,
     if (args.size() > 1 && !args[1].empty()) {
       // but only if it is different from current value
       if (!currValueSet || currValue != args[1]) {
-        putEnvArg += args[1];
-        cmSystemTools::PutEnv(putEnvArg);
+        setENV(varName, args[1]);
       }
       // if there's extra arguments, warn user
       // that they are ignored by this command.
@@ -61,7 +74,7 @@ bool cmSetCommand(std::vector<std::string> const& args,
 
     // if it will be cleared, then clear it if it isn't already clear
     if (currValueSet) {
-      cmSystemTools::PutEnv(putEnvArg);
+      setENV(varName, ""_s);
     }
     return true;
   }

Tests/RunCMake/CMP0194/CMP0194-common.cmake

@@ -1,3 +1,3 @@
 enable_language(C)
-set(ENV{PATH} "")
+unset(ENV{PATH})
 enable_language(ASM)

Tests/RunCMake/FindLua/FindLuaTest.cmake

@@ -9,8 +9,8 @@ set(ENV{CMAKE_INCLUDE_PATH} )
 set(ENV{CMAKE_PREFIX_PATH} )
 set(ENV{CMAKE_FRAMEWORK_PATH} )
 
-set(ENV{PATH} )
-set(ENV{INCLUDE} )
+unset(ENV{PATH})
+unset(ENV{INCLUDE})
 
 set(CMAKE_SYSTEM_INCLUDE_PATH )
 set(CMAKE_SYSTEM_PREFIX_PATH )

Tests/RunCMake/set/Env-stdout-windows.txt

@@ -0,0 +1,2 @@
+^-- ENV{UNSET_THEN_EMPTY} is not defined
+-- ENV{SET_THEN_EMPTY} is not defined$

Tests/RunCMake/set/Env-stdout.txt

@@ -0,0 +1,2 @@
+^-- ENV{UNSET_THEN_EMPTY} is not defined
+-- ENV{SET_THEN_EMPTY} is defined to ''$

Tests/RunCMake/set/Env.cmake

@@ -0,0 +1,15 @@
+unset(ENV{UNSET_THEN_EMPTY})
+set(ENV{UNSET_THEN_EMPTY} "")
+if(DEFINED ENV{UNSET_THEN_EMPTY})
+  message(STATUS "ENV{UNSET_THEN_EMPTY} is defined to '$ENV{UNSET_THEN_EMPTY}'")
+else()
+  message(STATUS "ENV{UNSET_THEN_EMPTY} is not defined")
+endif()
+
+set(ENV{SET_THEN_EMPTY} "set")
+set(ENV{SET_THEN_EMPTY} "")
+if(DEFINED ENV{SET_THEN_EMPTY})
+  message(STATUS "ENV{SET_THEN_EMPTY} is defined to '$ENV{SET_THEN_EMPTY}'")
+else()
+  message(STATUS "ENV{SET_THEN_EMPTY} is not defined")
+endif()

Tests/RunCMake/set/RunCMakeTest.cmake

@@ -12,3 +12,6 @@ run_cmake(CacheUnknownArguments)
 run_cmake(CacheMissingArguments)
 run_cmake(CacheWrongTYPE)
 run_cmake(CacheSetUnset)
+
+# set(ENV{}) syntax
+run_cmake_script(Env)