1 files changed, 38 insertions, 39 deletions

diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index 8090e00..7e56818 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -920,6 +920,20 @@ std::vector<BT<std::string>> cmLocalGenerator::GetIncludeDirectoriesImplicit(
     return result;
   }
 
+  // Standard include directories to be added unconditionally at the end.
+  // These are intended to simulate additional implicit include directories.
+  std::vector<std::string> userStandardDirs;
+  {
+    std::string key = "CMAKE_";
+    key += lang;
+    key += "_STANDARD_INCLUDE_DIRECTORIES";
+    std::string const value = this->Makefile->GetSafeDefinition(key);
+    cmSystemTools::ExpandListArgument(value, userStandardDirs);
+    for (std::string& usd : userStandardDirs) {
+      cmSystemTools::ConvertToUnixSlashes(usd);
+    }
+  }
+
   // Implicit include directories
   std::vector<std::string> implicitDirs;
   std::set<std::string> implicitSet;
@@ -928,24 +942,27 @@ std::vector<BT<std::string>> cmLocalGenerator::GetIncludeDirectoriesImplicit(
     return (implicitSet.find(dir) == implicitSet.end());
   };
   {
-    std::string rootPath;
-    if (const char* sysrootCompile =
-          this->Makefile->GetDefinition("CMAKE_SYSROOT_COMPILE")) {
-      rootPath = sysrootCompile;
-    } else {
-      rootPath = this->Makefile->GetSafeDefinition("CMAKE_SYSROOT");
-    }
-    cmSystemTools::ConvertToUnixSlashes(rootPath);
-
     // Raw list of implicit include directories
-    std::vector<std::string> impDirVec;
+    // Start with "standard" directories that we unconditionally add below.
+    std::vector<std::string> impDirVec = userStandardDirs;
 
     // Load implicit include directories for this language.
-    std::string key = "CMAKE_";
-    key += lang;
-    key += "_IMPLICIT_INCLUDE_DIRECTORIES";
-    if (const char* value = this->Makefile->GetDefinition(key)) {
-      cmSystemTools::ExpandListArgument(value, impDirVec);
+    // We ignore this for Fortran because:
+    // * There are no standard library headers to avoid overriding.
+    // * Compilers like gfortran do not search their own implicit include
+    //   directories for modules ('.mod' files).
+    if (lang != "Fortran") {
+      std::string key = "CMAKE_";
+      key += lang;
+      key += "_IMPLICIT_INCLUDE_DIRECTORIES";
+      if (const char* value = this->Makefile->GetDefinition(key)) {
+        size_t const impDirVecOldSize = impDirVec.size();
+        cmSystemTools::ExpandListArgument(value, impDirVec);
+        // FIXME: Use cmRange with 'advance()' when it supports non-const.
+        for (size_t i = impDirVecOldSize; i < impDirVec.size(); ++i) {
+          cmSystemTools::ConvertToUnixSlashes(impDirVec[i]);
+        }
+      }
     }
 
     // The Platform/UnixPaths module used to hard-code /usr/include for C, CXX,
@@ -965,13 +982,8 @@ std::vector<BT<std::string>> cmLocalGenerator::GetIncludeDirectoriesImplicit(
     }
 
     for (std::string const& i : impDirVec) {
-      std::string imd = i;
-      cmSystemTools::ConvertToUnixSlashes(imd);
-      if (!rootPath.empty() && !cmHasPrefix(imd, rootPath)) {
-        imd = rootPath + imd;
-      }
-      if (implicitSet.insert(imd).second) {
-        implicitDirs.emplace_back(std::move(imd));
+      if (implicitSet.insert(i).second) {
+        implicitDirs.emplace_back(i);
       }
     }
   }
@@ -1010,23 +1022,10 @@ std::vector<BT<std::string>> cmLocalGenerator::GetIncludeDirectoriesImplicit(
   MoveSystemIncludesToEnd(result, config, lang, target);
 
   // Append standard include directories for this language.
-  {
-    std::vector<std::string> userStandardDirs;
-    {
-      std::string key = "CMAKE_";
-      key += lang;
-      key += "_STANDARD_INCLUDE_DIRECTORIES";
-      std::string const value = this->Makefile->GetSafeDefinition(key);
-      cmSystemTools::ExpandListArgument(value, userStandardDirs);
-    }
-    userDirs.reserve(userDirs.size() + userStandardDirs.size());
-    for (std::string& usd : userStandardDirs) {
-      cmSystemTools::ConvertToUnixSlashes(usd);
-      if (notImplicit(usd)) {
-        emitDir(usd);
-      }
-      userDirs.emplace_back(std::move(usd));
-    }
+  userDirs.reserve(userDirs.size() + userStandardDirs.size());
+  for (std::string& usd : userStandardDirs) {
+    emitDir(usd);
+    userDirs.emplace_back(std::move(usd));
   }
 
   // Append compiler implicit include directories