From 8ec7408d745a9e17a1e35a4e97e9ab33044832c9 Mon Sep 17 00:00:00 2001
From: Marc Chevrier <marc.chevrier@gmail.com>
Date: Wed, 6 Jan 2021 13:52:53 +0100
Subject: Makefile dependencies: ensure long paths are used on Windows

---
 Source/cmGccDepfileReader.cxx | 23 ++++++++---------------
 Source/cmGccDepfileReader.h   |  6 ++----
 Source/cmSystemTools.cxx      | 24 ++++++++++++++++++++++++
 Source/cmSystemTools.h        |  6 ++++++
 Source/cmcmd.cxx              |  9 ++++-----
 5 files changed, 44 insertions(+), 24 deletions(-)

diff --git a/Source/cmGccDepfileReader.cxx b/Source/cmGccDepfileReader.cxx
index 96a562e..8253375 100644
--- a/Source/cmGccDepfileReader.cxx
+++ b/Source/cmGccDepfileReader.cxx
@@ -12,40 +12,33 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 
-cm::optional<cmGccDepfileContent> cmReadGccDepfile(const char* filePath)
-{
-  cmGccDepfileLexerHelper helper;
-  if (helper.readFile(filePath)) {
-    return cm::make_optional(std::move(helper).extractContent());
-  }
-  return cm::nullopt;
-}
-
 cm::optional<cmGccDepfileContent> cmReadGccDepfile(const char* filePath,
                                                    const std::string& prefix)
 {
-  auto deps = cmReadGccDepfile(filePath);
-
-  if (prefix.empty() || !deps) {
-    return deps;
+  cmGccDepfileLexerHelper helper;
+  if (!helper.readFile(filePath)) {
+    return cm::nullopt;
   }
+  auto deps = cm::make_optional(std::move(helper).extractContent());
 
   for (auto& dep : *deps) {
     for (auto& rule : dep.rules) {
-      if (!cmSystemTools::FileIsFullPath(rule)) {
+      if (!prefix.empty() && !cmSystemTools::FileIsFullPath(rule)) {
         rule = cmStrCat(prefix, rule);
       }
       if (cmSystemTools::FileIsFullPath(rule)) {
         rule = cmSystemTools::CollapseFullPath(rule);
       }
+      cmSystemTools::ConvertToLongPath(rule);
     }
     for (auto& path : dep.paths) {
-      if (!cmSystemTools::FileIsFullPath(path)) {
+      if (!prefix.empty() && !cmSystemTools::FileIsFullPath(path)) {
         path = cmStrCat(prefix, path);
       }
       if (cmSystemTools::FileIsFullPath(path)) {
         path = cmSystemTools::CollapseFullPath(path);
       }
+      cmSystemTools::ConvertToLongPath(path);
     }
   }
 
diff --git a/Source/cmGccDepfileReader.h b/Source/cmGccDepfileReader.h
index 66ff75d..c8a3748 100644
--- a/Source/cmGccDepfileReader.h
+++ b/Source/cmGccDepfileReader.h
@@ -8,10 +8,8 @@
 
 #include "cmGccDepfileReaderTypes.h"
 
-cm::optional<cmGccDepfileContent> cmReadGccDepfile(const char* filePath);
-
 /*
  * Read dependencies file and append prefix to all relative paths
  */
-cm::optional<cmGccDepfileContent> cmReadGccDepfile(const char* filePath,
-                                                   const std::string& prefix);
+cm::optional<cmGccDepfileContent> cmReadGccDepfile(
+  const char* filePath, const std::string& prefix = {});
diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx
index 6a705f4..024356f 100644
--- a/Source/cmSystemTools.cxx
+++ b/Source/cmSystemTools.cxx
@@ -1255,6 +1255,30 @@ void cmSystemTools::ConvertToOutputSlashes(std::string& path)
 #endif
 }
 
+void cmSystemTools::ConvertToLongPath(std::string& path)
+{
+#if defined(_WIN32) && !defined(__CYGWIN__)
+  // Try to convert path to a long path only if the path contains character '~'
+  if (path.find('~') == std::string::npos) {
+    return;
+  }
+
+  std::wstring wPath = cmsys::Encoding::ToWide(path);
+  DWORD ret = GetLongPathNameW(wPath.c_str(), nullptr, 0);
+  std::vector<wchar_t> buffer(ret);
+  if (ret != 0) {
+    ret = GetLongPathNameW(wPath.c_str(), buffer.data(),
+                           static_cast<DWORD>(buffer.size()));
+  }
+
+  if (ret != 0) {
+    path = cmsys::Encoding::ToNarrow(buffer.data());
+  }
+#else
+  static_cast<void>(path);
+#endif
+}
+
 std::string cmSystemTools::ConvertToRunCommandPath(const std::string& path)
 {
 #if defined(_WIN32) && !defined(__CYGWIN__)
diff --git a/Source/cmSystemTools.h b/Source/cmSystemTools.h
index 1100f05..5bbbb0c 100644
--- a/Source/cmSystemTools.h
+++ b/Source/cmSystemTools.h
@@ -287,6 +287,12 @@ public:
   // running cmake needs paths to be in its format
   static std::string ConvertToRunCommandPath(const std::string& path);
 
+  /**
+   * For windows computes the long path for the given path,
+   * For Unix, it is a noop
+   */
+  static void ConvertToLongPath(std::string& path);
+
   /** compute the relative path from local to remote.  local must
       be a directory.  remote can be a file or a directory.
       Both remote and local must be full paths.  Basically, if
diff --git a/Source/cmcmd.cxx b/Source/cmcmd.cxx
index 4c0fbeb..851205e 100644
--- a/Source/cmcmd.cxx
+++ b/Source/cmcmd.cxx
@@ -231,11 +231,10 @@ private:
   bool ProcessLine() override
   {
     if (cmHasPrefix(this->Line, this->IncludePrefix)) {
-      this->DepFile << cmCMakePath(
-                         cmTrimWhitespace(this->Line.c_str() +
-                                          this->IncludePrefix.size()))
-                         .GenericString()
-                    << std::endl;
+      auto path =
+        cmTrimWhitespace(this->Line.c_str() + this->IncludePrefix.size());
+      cmSystemTools::ConvertToLongPath(path);
+      this->DepFile << cmCMakePath(path).GenericString() << std::endl;
     } else {
       this->Output << this->Line << std::endl << std::flush;
     }
-- 
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