WIN32: Linking with the CRT at runtime. (#570)

Disclaimer: Forgive me if my format sucks, I've never submitted a PR before!

Fixes: #517 

I added a few things to allow zig to link with the CRT properly both statically and dynamically. In Visual Studio 2017, Microsoft changed how the c-runtime is factored again. With this change, they also added a COM interface to allow you to query the respective Visual Studio instance for two of them. This does that and also falls back on a registry query for 2015 support. If you're using a Visual Studio instance older than 2015, you'll have to use the existing options available with the zig compiler. Changes are listed below along with a general description of the changes.

all_types.cpp:

The separate variables for msvc/kern32 have been removed and all win32 libc directory paths have been combined into a ZigList since we're querying more than two directories and differentiating one from another doesn't matter to lld.

analyze.cpp:

The existing functions were extended to support querying libc libs & libc headers at runtime.

codegen.cpp/hpp:

Microsoft uses the new 'Universal C Runtime' name now. Doesn't matter from a functionality standpoint. I left the compiler switches as is to not introduce any breaking changes.

link.cpp:

We're linking 4 libs and generating another in order to support the UCRT.
Dynamic: msvcrt/d, vcruntime/d, ucrt/d, legacy_stdio_definitions.lib
Static: libcmt/d, libvcruntime/d libucrt/d, legacy_stdio_definitions.lib

main.cpp:

Update function call names.

os.cpp/hpp:

COM/Registry interface for querying Windows UCRT/SDK.

Sources:
[Windows CRT](https://docs.microsoft.com/en-us/cpp/c-runtime-library/crt-library-features)
[VS 2015 Breaking Changes](https://msdn.microsoft.com/en-us/library/bb531344.aspx)

src/all_types.hpp

@@ -35,6 +35,7 @@ struct IrInstruction;
 struct IrInstructionCast;
 struct IrBasicBlock;
 struct ScopeDecls;
+struct ZigWindowsSDK;
 
 struct IrGotoItem {
     AstNode *source_node;
@@ -1461,17 +1462,17 @@ struct CodeGen {
     bool have_winmain_crt_startup;
     bool have_dllmain_crt_startup;
     bool have_pub_panic;
+    ZigList<Buf*> libc_lib_dirs_list;
     Buf *libc_lib_dir;
     Buf *libc_static_lib_dir;
     Buf *libc_include_dir;
-    Buf *msvc_lib_dir;
-    Buf *kernel32_lib_dir;
     Buf *zig_lib_dir;
     Buf *zig_std_dir;
     Buf *zig_c_headers_dir;
     Buf *zig_std_special_dir;
     Buf *dynamic_linker;
     Buf *ar_path;
+    ZigWindowsSDK *win_sdk;
     Buf triple_str;
     BuildMode build_mode;
     bool is_test_build;

src/analyze.cpp

@@ -1,4 +1,4 @@
-/*
+/*
  * Copyright (c) 2015 Andrew Kelley
  *
  * This file is part of zig, which is MIT licensed.
@@ -3371,65 +3371,57 @@ bool handle_is_ptr(TypeTableEntry *type_entry) {
 }
 
 void find_libc_include_path(CodeGen *g) {
+#ifdef ZIG_OS_WINDOWS
     if (!g->libc_include_dir || buf_len(g->libc_include_dir) == 0) {
+        if (g->win_sdk == nullptr) {
+            if (os_find_windows_sdk(&g->win_sdk)) {
+                zig_panic("Unable to determine Windows SDK path.");
+            }
+        }
+
+        if (g->zig_target.os == ZigLLVM_Win32) {
+            if (os_get_win32_ucrt_include_path(g->win_sdk, g->libc_include_dir)) {
+                zig_panic("Unable to determine libc include path.");
+            }
+        }
+    }
+    return;
+#endif
+    // TODO find libc at runtime for other operating systems
+    if(!g->libc_include_dir || buf_len(g->libc_include_dir) == 0) {
         zig_panic("Unable to determine libc include path.");
     }
 }
 
 void find_libc_lib_path(CodeGen *g) {
 #ifdef ZIG_OS_WINDOWS
-    if (!g->msvc_lib_dir && g->zig_target.os == ZigLLVM_Win32) {
-        Buf *msvc_lib_dir;
-        if (g->zig_target.arch.arch == ZigLLVM_arm) {
-            msvc_lib_dir = buf_create_from_str("C:\\Program Files (x86)\\Microsoft Visual Studio 14.0\\VC\\lib\\arm");
-        } else if (g->zig_target.arch.arch == ZigLLVM_x86_64) {
-            msvc_lib_dir = buf_create_from_str("C:\\Program Files (x86)\\Microsoft Visual Studio 14.0\\VC\\lib\\amd64");
-        } else if (g->zig_target.arch.arch == ZigLLVM_x86) {
-            msvc_lib_dir = buf_create_from_str("C:\\Program Files (x86)\\Microsoft Visual Studio 14.0\\VC\\lib");
-        } else {
-            zig_panic("unable to determine msvc lib path");
-        }
-        Buf *test_path = buf_alloc();
-        os_path_join(msvc_lib_dir, buf_create_from_str("vcruntime.lib"), test_path);
-        bool result;
-        int err;
-        if ((err = os_file_exists(test_path, &result))) {
-            result = false;
-        }
-        if (result) {
-            g->msvc_lib_dir = msvc_lib_dir;
-        } else {
-            zig_panic("Unable to determine msvc lib path.");
+    if (g->zig_target.os == ZigLLVM_Win32) {
+        if (g->win_sdk == nullptr) {
+            if (os_find_windows_sdk(&g->win_sdk)) {
+                zig_panic("Unable to determine Windows SDK path.");
+            }
         }
-    }
 
-    if (!g->kernel32_lib_dir && g->zig_target.os == ZigLLVM_Win32) {
-        Buf *kernel32_lib_dir;
-        if (g->zig_target.arch.arch == ZigLLVM_arm) {
-            kernel32_lib_dir = buf_create_from_str(
-                "C:\\Program Files (x86)\\Windows Kits\\8.1\\Lib\\winv6.3\\um\\arm");
-        } else if (g->zig_target.arch.arch == ZigLLVM_x86_64) {
-            kernel32_lib_dir = buf_create_from_str(
-                "C:\\Program Files (x86)\\Windows Kits\\8.1\\Lib\\winv6.3\\um\\x64");
-        } else if (g->zig_target.arch.arch == ZigLLVM_x86) {
-            kernel32_lib_dir = buf_create_from_str(
-                "C:\\Program Files (x86)\\Windows Kits\\8.1\\Lib\\winv6.3\\um\\x86");
-        } else {
-            zig_panic("unable to determine kernel32 lib path");
+        Buf* vc_lib_dir = buf_alloc();
+        if (os_get_win32_vcruntime_path(vc_lib_dir, g->zig_target.arch.arch)) {
+            zig_panic("Unable to determine vcruntime path.");
         }
-        Buf *test_path = buf_alloc();
-        os_path_join(kernel32_lib_dir, buf_create_from_str("kernel32.lib"), test_path);
-        bool result;
-        int err;
-        if ((err = os_file_exists(test_path, &result))) {
-            result = false;
+
+        Buf* ucrt_lib_path = buf_alloc();
+        if (os_get_win32_ucrt_lib_path(g->win_sdk, ucrt_lib_path, g->zig_target.arch.arch)) {
+            zig_panic("Unable to determine ucrt path.");
         }
-        if (result) {
-            g->kernel32_lib_dir = kernel32_lib_dir;
-        } else {
-            zig_panic("Unable to determine kernel32 lib path.");
+
+        Buf* kern_lib_path = buf_alloc();
+        if (os_get_win32_kern32_path(g->win_sdk, kern_lib_path, g->zig_target.arch.arch)) {
+            zig_panic("Unable to determine kernel32 path.");
         }
+
+        g->libc_lib_dirs_list.append(vc_lib_dir);
+        g->libc_lib_dirs_list.append(ucrt_lib_path);
+        g->libc_lib_dirs_list.append(kern_lib_path);
     }
+    return;
 #endif
 
     // later we can handle this better by reporting an error via the normal mechanism

src/codegen.cpp

@@ -85,7 +85,6 @@ CodeGen *codegen_create(Buf *root_src_path, const ZigTarget *target, OutType out
     g->external_prototypes.init(8);
     g->is_test_build = false;
     g->want_h_file = (out_type == OutTypeObj || out_type == OutTypeLib);
-
     buf_resize(&g->global_asm, 0);
 
     // reserve index 0 to indicate no error
@@ -106,31 +105,25 @@ CodeGen *codegen_create(Buf *root_src_path, const ZigTarget *target, OutType out
     g->zig_std_special_dir = buf_alloc();
     os_path_join(g->zig_std_dir, buf_sprintf("special"), g->zig_std_special_dir);
 
-
     if (target) {
         // cross compiling, so we can't rely on all the configured stuff since
         // that's for native compilation
         g->zig_target = *target;
         resolve_target_object_format(&g->zig_target);
-
         g->dynamic_linker = buf_create_from_str("");
         g->libc_lib_dir = buf_create_from_str("");
         g->libc_static_lib_dir = buf_create_from_str("");
         g->libc_include_dir = buf_create_from_str("");
-        g->msvc_lib_dir = nullptr;
-        g->kernel32_lib_dir = nullptr;
         g->each_lib_rpath = false;
     } else {
         // native compilation, we can rely on the configuration stuff
         g->is_native_target = true;
         get_native_target(&g->zig_target);
-
         g->dynamic_linker = buf_create_from_str(ZIG_DYNAMIC_LINKER);
         g->libc_lib_dir = buf_create_from_str(ZIG_LIBC_LIB_DIR);
         g->libc_static_lib_dir = buf_create_from_str(ZIG_LIBC_STATIC_LIB_DIR);
         g->libc_include_dir = buf_create_from_str(ZIG_LIBC_INCLUDE_DIR);
-        g->msvc_lib_dir = nullptr; // find it at runtime
-        g->kernel32_lib_dir = nullptr; // find it at runtime
+
 #ifdef ZIG_EACH_LIB_RPATH
         g->each_lib_rpath = true;
 #endif
@@ -228,14 +221,6 @@ void codegen_set_libc_include_dir(CodeGen *g, Buf *libc_include_dir) {
     g->libc_include_dir = libc_include_dir;
 }
 
-void codegen_set_msvc_lib_dir(CodeGen *g, Buf *msvc_lib_dir) {
-    g->msvc_lib_dir = msvc_lib_dir;
-}
-
-void codegen_set_kernel32_lib_dir(CodeGen *g, Buf *kernel32_lib_dir) {
-    g->kernel32_lib_dir = kernel32_lib_dir;
-}
-
 void codegen_set_dynamic_linker(CodeGen *g, Buf *dynamic_linker) {
     g->dynamic_linker = dynamic_linker;
 }
@@ -244,6 +229,14 @@ void codegen_add_lib_dir(CodeGen *g, const char *dir) {
     g->lib_dirs.append(dir);
 }
 
+void codegen_set_ucrt_lib_dir(CodeGen *g, Buf *ucrt_lib_dir) {
+    g->libc_lib_dirs_list.append(ucrt_lib_dir);
+}
+
+void codegen_set_kernel32_lib_dir(CodeGen *g, Buf *kernel32_lib_dir) {
+    g->libc_lib_dirs_list.append(kernel32_lib_dir);
+}
+
 void codegen_add_rpath(CodeGen *g, const char *name) {
     g->rpath_list.append(buf_create_from_str(name));
 }

src/codegen.hpp

@@ -30,7 +30,7 @@ void codegen_set_out_name(CodeGen *codegen, Buf *out_name);
 void codegen_set_libc_lib_dir(CodeGen *codegen, Buf *libc_lib_dir);
 void codegen_set_libc_static_lib_dir(CodeGen *g, Buf *libc_static_lib_dir);
 void codegen_set_libc_include_dir(CodeGen *codegen, Buf *libc_include_dir);
-void codegen_set_msvc_lib_dir(CodeGen *codegen, Buf *msvc_lib_dir);
+void codegen_set_ucrt_lib_dir(CodeGen *g, Buf *ucrt_lib_dir);
 void codegen_set_kernel32_lib_dir(CodeGen *codegen, Buf *kernel32_lib_dir);
 void codegen_set_dynamic_linker(CodeGen *g, Buf *dynamic_linker);
 void codegen_set_windows_subsystem(CodeGen *g, bool mwindows, bool mconsole);

src/link.cpp

@@ -402,26 +402,35 @@ static void construct_linker_job_coff(LinkJob *lj) {
     lj->args.append(buf_ptr(buf_sprintf("-OUT:%s", buf_ptr(&lj->out_file))));
 
     if (g->libc_link_lib != nullptr) {
-        lj->args.append(buf_ptr(buf_sprintf("-LIBPATH:%s", buf_ptr(g->msvc_lib_dir))));
-        lj->args.append(buf_ptr(buf_sprintf("-LIBPATH:%s", buf_ptr(g->kernel32_lib_dir))));
-
-        lj->args.append(buf_ptr(buf_sprintf("-LIBPATH:%s", buf_ptr(g->libc_lib_dir))));
-        lj->args.append(buf_ptr(buf_sprintf("-LIBPATH:%s", buf_ptr(g->libc_static_lib_dir))));
+        if (g->libc_link_lib != nullptr) {
+            for (uint32_t i = 0; i < g->libc_lib_dirs_list.length; ++i) {
+                lj->args.append(buf_ptr(buf_sprintf("-LIBPATH:%s", buf_ptr(g->libc_lib_dirs_list.items[i]))));
+            }
+        }
     }
 
     if (lj->link_in_crt) {
         const char *lib_str = g->is_static ? "lib" : "";
         const char *d_str = (g->build_mode == BuildModeDebug) ? "d" : "";
 
-        Buf *cmt_lib_name = buf_sprintf("libcmt%s.lib", d_str);
-        lj->args.append(buf_ptr(cmt_lib_name));
+        if (g->is_static) {
+            Buf *cmt_lib_name = buf_sprintf("libcmt%s.lib", d_str);
+            lj->args.append(buf_ptr(cmt_lib_name));
+        }
+        else {
+            Buf *msvcrt_lib_name = buf_sprintf("msvcrt%s.lib", d_str);
+            lj->args.append(buf_ptr(msvcrt_lib_name));
+        }
 
         Buf *vcruntime_lib_name = buf_sprintf("%svcruntime%s.lib", lib_str, d_str);
         lj->args.append(buf_ptr(vcruntime_lib_name));
 
         Buf *crt_lib_name = buf_sprintf("%sucrt%s.lib", lib_str, d_str);
         lj->args.append(buf_ptr(crt_lib_name));
 
+        //Visual C++ 2015 Conformance Changes
+        //https://msdn.microsoft.com/en-us/library/bb531344.aspx
+        lj->args.append("legacy_stdio_definitions.lib");
 
         //if (shared || dll) {
         //    lj->args.append(get_libc_file(g, "dllcrt2.o"));

src/main.cpp

@@ -758,7 +758,7 @@ int main(int argc, char **argv) {
             if (libc_include_dir)
                 codegen_set_libc_include_dir(g, buf_create_from_str(libc_include_dir));
             if (msvc_lib_dir)
-                codegen_set_msvc_lib_dir(g, buf_create_from_str(msvc_lib_dir));
+                codegen_set_ucrt_lib_dir(g, buf_create_from_str(msvc_lib_dir));
             if (kernel32_lib_dir)
                 codegen_set_kernel32_lib_dir(g, buf_create_from_str(kernel32_lib_dir));
             if (dynamic_linker)