From e7bff1cf7a0dd456d333ff399f6095c5898630b4 Mon Sep 17 00:00:00 2001
From: Martin Kinkelin <noone@nowhere.com>
Date: Tue, 7 Nov 2023 01:42:18 +0100
Subject: [PATCH] VSOptions: Prepare for setting the INCLUDE env var for
 importC

Upstreaming from LDC, to pave the way for fixing Issue 24111.
---
 compiler/src/dmd/vsoptions.d | 36 ++++++++++++++++++++++++++++++++++++
 compiler/src/dmd/vsoptions.h |  2 ++
 2 files changed, 38 insertions(+)

diff --git a/compiler/src/dmd/vsoptions.d b/compiler/src/dmd/vsoptions.d
index d735040c1b62..be8f735c6055 100644
--- a/compiler/src/dmd/vsoptions.d
+++ b/compiler/src/dmd/vsoptions.d
@@ -471,6 +471,18 @@ public:
         return FileName.exists(proposed) ? proposed : null;
     }
 
+    const(char)* getVCIncludeDir() const
+    {
+        const(char)* proposed;
+
+        if (VCToolsInstallDir !is null)
+            proposed = FileName.combine(VCToolsInstallDir, "include");
+        else if (VCInstallDir !is null)
+            proposed = FileName.combine(VCInstallDir, "include");
+
+        return FileName.exists(proposed) ? proposed : null;
+    }
+
     /**
      * get the path to the universal CRT libraries
      * Params:
@@ -528,6 +540,30 @@ public:
         return null;
     }
 
+    const(char)* getSDKIncludePath() const
+    {
+        if (WindowsSdkDir)
+        {
+            alias umExists = returnDirIfContainsFile!"um"; // subdir in this case
+
+            const sdk = FileName.combine(WindowsSdkDir.toDString, "include");
+            if (WindowsSdkVersion)
+            {
+                if (auto p = umExists(sdk, WindowsSdkVersion.toDString)) // SDK 10.0
+                    return p;
+            }
+            // purely speculative
+            if (auto p = umExists(sdk, "win8")) // SDK 8.0
+                return p;
+            if (auto p = umExists(sdk, "winv6.3")) // SDK 8.1
+                return p;
+            if (auto p = umExists(sdk)) // SDK 7.1 or earlier
+                return p;
+        }
+
+        return null;
+    }
+
 private:
 extern(D):
 
diff --git a/compiler/src/dmd/vsoptions.h b/compiler/src/dmd/vsoptions.h
index fc63e1c1b9b3..5c6a7c38257a 100644
--- a/compiler/src/dmd/vsoptions.h
+++ b/compiler/src/dmd/vsoptions.h
@@ -25,8 +25,10 @@ struct VSOptions
     void initialize();
     const char *getVCBinDir(bool x64, const char *&addpath) const;
     const char *getVCLibDir(bool x64) const;
+    const char *getVCIncludeDir() const;
     const char *getUCRTLibPath(bool x64) const;
     const char *getSDKLibPath(bool x64) const;
+    const char *getSDKIncludePath() const;
 };
 
 #endif // _WIN32