From dd54f7809e2a3fc7e4e51a999c5b34fc4f2c52da Mon Sep 17 00:00:00 2001
From: SHOO <zan77137@nifty.com>
Date: Sun, 25 Feb 2024 22:59:56 +0900
Subject: [PATCH 1/2] Fix Bugzilla issue 24111 - [ImportC] fatal error C1034:
 stdio.h: no include path set

---
 compiler/src/dmd/link.d | 51 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/compiler/src/dmd/link.d b/compiler/src/dmd/link.d
index 9302b0dd8ac9..b467f9ba0877 100644
--- a/compiler/src/dmd/link.d
+++ b/compiler/src/dmd/link.d
@@ -1168,6 +1168,57 @@ public DArray!ubyte runPreprocessor(ref const Loc loc, const(char)[] cpp, const(
                 // Convert command to wchar
                 wchar[1024] scratch = void;
                 auto smbuf = SmallBuffer!wchar(scratch.length, scratch[]);
+
+                // INCLUDE
+                static VSOptions vsopt; // cache, as this can be expensive
+                static Strings includePaths;
+                if (includePaths.length == 0)
+                {
+                    if (!vsopt.VSInstallDir)
+                        vsopt.initialize();
+
+                    if (auto vcincludedir = vsopt.getVCIncludeDir()) {
+                        includePaths.push(vcincludedir);
+                    } else {
+                        return DArray!ubyte();
+                    }
+                    if (auto sdkincludedir = vsopt.getSDKIncludePath()) {
+                        includePaths.push(FileName.combine(sdkincludedir, "ucrt"));
+                        includePaths.push(FileName.combine(sdkincludedir, "shared"));
+                        includePaths.push(FileName.combine(sdkincludedir, "um"));
+                        includePaths.push(FileName.combine(sdkincludedir, "winrt"));
+                        includePaths.push(FileName.combine(sdkincludedir, "cppwinrt"));
+                    } else {
+                        includePaths = Strings.init;
+                        return DArray!ubyte();
+                    }
+                }
+
+                // Get current environment variable and rollback
+                auto oldIncludePathLen = GetEnvironmentVariableW("INCLUDE"w.ptr, null, 0);
+                wchar* oldIncludePaths = cast(wchar*)mem.xmalloc(oldIncludePathLen * wchar.sizeof);
+                oldIncludePathLen = GetEnvironmentVariableW("INCLUDE"w.ptr, oldIncludePaths, oldIncludePathLen);
+                scope (exit)
+                {
+                    SetEnvironmentVariableW("INCLUDE"w.ptr, oldIncludePaths);
+                    mem.xfree(oldIncludePaths);
+                }
+
+                // Make new environment variable
+                OutBuffer envbuf;
+                foreach (inc; includePaths[])
+                {
+                    if (FileName.exists(inc) == 2)
+                    {
+                        envbuf.write(cast(const ubyte[])toWStringz(inc[0..strlen(inc)], smbuf));
+                        envbuf.writewchar(';');
+                    }
+                }
+                envbuf.write(cast(const ubyte[])oldIncludePaths[0..oldIncludePathLen]);
+                envbuf.writewchar('\0');
+                // Temporarily set INCLUDE environment variable
+                SetEnvironmentVariableW("INCLUDE"w.ptr, cast(LPCWSTR)envbuf.buf);
+
                 auto szCommand = toWStringz(buf.peekChars()[0 .. buf.length], smbuf);
 
                 int exitCode = runProcessCollectStdout(szCommand.ptr, buffer[], &sink);

From 17500e6c56afaa2e9e6b28e78029ec240fa083be Mon Sep 17 00:00:00 2001
From: SHOO <zan77137@nifty.com>
Date: Thu, 29 Feb 2024 00:15:04 +0900
Subject: [PATCH 2/2] Add a testcase

---
 compiler/test/dshell/extra-files/issue24111.c |  1 +
 compiler/test/dshell/issue24111.d             | 15 +++++++++++++++
 2 files changed, 16 insertions(+)
 create mode 100644 compiler/test/dshell/extra-files/issue24111.c
 create mode 100644 compiler/test/dshell/issue24111.d

diff --git a/compiler/test/dshell/extra-files/issue24111.c b/compiler/test/dshell/extra-files/issue24111.c
new file mode 100644
index 000000000000..53c5fdf17996
--- /dev/null
+++ b/compiler/test/dshell/extra-files/issue24111.c
@@ -0,0 +1 @@
+#include <stdio.h>
diff --git a/compiler/test/dshell/issue24111.d b/compiler/test/dshell/issue24111.d
new file mode 100644
index 000000000000..175cae478463
--- /dev/null
+++ b/compiler/test/dshell/issue24111.d
@@ -0,0 +1,15 @@
+import dshell;
+
+int main()
+{
+	version (Windows)
+	{
+		auto cmd = "$DMD -m$MODEL -c $EXTRA_FILES" ~ SEP ~ "issue24111.c";
+		run(cmd);
+
+		import std.process: environment;
+		environment.remove("INCLUDE");
+		run(cmd);
+	}
+	return 0;
+}