Switch windows to clang (#7407)

* Switch over to clang for deepseek on windows

The patch for deepseek requires clang on windows. gcc on windows
has a buggy c++ library and can't handle the unicode characters

* Fail fast with wrong compiler on windows

Avoid users mistakenly building with GCC when we need clang

docs/development.md

@@ -296,10 +296,13 @@ The following tools are required as a minimal development environment to build C
   - https://go.dev/dl/
 - Git
   - https://git-scm.com/download/win
-- GCC and Make.  There are multiple options on how to go about installing these tools on Windows.  We have verified the following, but others may work as well:  
+- clang with gcc compat and Make.  There are multiple options on how to go about installing these tools on Windows.  We have verified the following, but others may work as well:  
   - [MSYS2](https://www.msys2.org/)
-    - After installing, from an MSYS2 terminal, run `pacman -S mingw-w64-ucrt-x86_64-gcc make` to install the required tools
-  - Assuming you used the default install prefix for msys2 above, add `c:\msys64\ucrt64\bin` and `c:\msys64\usr\bin` to your environment variable `PATH` where you will perform the build steps below (e.g. system-wide, account-level, powershell, cmd, etc.)
+    - After installing, from an MSYS2 terminal, run `pacman -S mingw-w64-clang-x86_64-gcc-compat mingw-w64-clang-x86_64-clang make` to install the required tools
+  - Assuming you used the default install prefix for msys2 above, add `C:\msys64\clang64\bin` and `c:\msys64\usr\bin` to your environment variable `PATH` where you will perform the build steps below (e.g. system-wide, account-level, powershell, cmd, etc.)
+
+> [!NOTE]  
+> Due to bugs in the GCC C++ library for unicode support, Ollama requires clang on windows.  If the gcc executable in your path is not the clang compatibility wrapper, the build will error.
 
 Then, build the `ollama` binary:
 

llama/make/common-defs.make

@@ -57,6 +57,10 @@ ifeq ($(OS),windows)
 	EXE_EXT := .exe
 	SHARED_PREFIX := 
 	CPU_FLAG_PREFIX := /arch:
+	_GCC_TEST:=$(findstring clang,$(shell gcc --version))
+	ifneq ($(_GCC_TEST),clang)
+$(error WRONG COMPILER DETECTED $(shell type gcc) - gcc must be a clang compat compiler on windows - see docs/development.md for setup instructions)
+	endif
 ifneq ($(HIP_PATH),)
 	# If HIP_PATH has spaces, hipcc trips over them when subprocessing
 	HIP_PATH := $(shell cygpath -m -s "$(patsubst %\,%,$(HIP_PATH))")