better libc detection (#1996)

* better libc detection

This introduces a new command `zig libc` which prints
the various paths of libc files. It outputs them to stdout
in a simple text file format that it is capable of parsing.
You can use `zig libc libc.txt` to validate a file.

These arguments are gone:
--libc-lib-dir [path]        directory where libc crt1.o resides
--libc-static-lib-dir [path] directory where libc crtbegin.o resides
--msvc-lib-dir [path]        (windows) directory where vcruntime.lib resides
--kernel32-lib-dir [path]    (windows) directory where kernel32.lib resides

Instead we have this argument:
--libc [file]                Provide a file which specifies libc paths

This is used to pass a libc text file (which can be generated with
`zig libc`). So it is easier to manage multiple cross compilation
environments.

`--cache on` now works when linking against libc.

`ZigTarget` now has a bool field `is_native`

Better error messaging when you try to link against libc or use
`@cImport` but the various paths cannot be found. It should also be
faster.

* save native_libc.txt in zig-cache

This avoids having to detect libc at runtime on every invocation.

1 files changed, 7 insertions, 7 deletions

diff --git a/src/os.cpp b/src/os.cpp
index c11840b1cf..95febca9bc 100644
--- a/src/os.cpp
+++ b/src/os.cpp
@@ -1550,7 +1550,7 @@ void os_stderr_set_color(TermColor color) {
 #endif
 }
 
-int os_get_win32_ucrt_lib_path(ZigWindowsSDK *sdk, Buf* output_buf, ZigLLVM_ArchType platform_type) {
+Error os_get_win32_ucrt_lib_path(ZigWindowsSDK *sdk, Buf* output_buf, ZigLLVM_ArchType platform_type) {
 #if defined(ZIG_OS_WINDOWS)
     buf_resize(output_buf, 0);
     buf_appendf(output_buf, "%s\\Lib\\%s\\ucrt\\", sdk->path10_ptr, sdk->version10_ptr);
@@ -1571,7 +1571,7 @@ int os_get_win32_ucrt_lib_path(ZigWindowsSDK *sdk, Buf* output_buf, ZigLLVM_Arch
     buf_init_from_buf(tmp_buf, output_buf);
     buf_append_str(tmp_buf, "ucrt.lib");
     if (GetFileAttributesA(buf_ptr(tmp_buf)) != INVALID_FILE_ATTRIBUTES) {
-        return 0;
+        return ErrorNone;
     }
     else {
         buf_resize(output_buf, 0);
@@ -1582,12 +1582,12 @@ int os_get_win32_ucrt_lib_path(ZigWindowsSDK *sdk, Buf* output_buf, ZigLLVM_Arch
 #endif
 }
 
-int os_get_win32_ucrt_include_path(ZigWindowsSDK *sdk, Buf* output_buf) {
+Error os_get_win32_ucrt_include_path(ZigWindowsSDK *sdk, Buf* output_buf) {
 #if defined(ZIG_OS_WINDOWS)
     buf_resize(output_buf, 0);
     buf_appendf(output_buf, "%s\\Include\\%s\\ucrt", sdk->path10_ptr, sdk->version10_ptr);
     if (GetFileAttributesA(buf_ptr(output_buf)) != INVALID_FILE_ATTRIBUTES) {
-        return 0;
+        return ErrorNone;
     }
     else {
         buf_resize(output_buf, 0);
@@ -1598,7 +1598,7 @@ int os_get_win32_ucrt_include_path(ZigWindowsSDK *sdk, Buf* output_buf) {
 #endif
 }
 
-int os_get_win32_kern32_path(ZigWindowsSDK *sdk, Buf* output_buf, ZigLLVM_ArchType platform_type) {
+Error os_get_win32_kern32_path(ZigWindowsSDK *sdk, Buf* output_buf, ZigLLVM_ArchType platform_type) {
 #if defined(ZIG_OS_WINDOWS)
     {
         buf_resize(output_buf, 0);
@@ -1620,7 +1620,7 @@ int os_get_win32_kern32_path(ZigWindowsSDK *sdk, Buf* output_buf, ZigLLVM_ArchTy
         buf_init_from_buf(tmp_buf, output_buf);
         buf_append_str(tmp_buf, "kernel32.lib");
         if (GetFileAttributesA(buf_ptr(tmp_buf)) != INVALID_FILE_ATTRIBUTES) {
-            return 0;
+            return ErrorNone;
         }
     }
     {
@@ -1643,7 +1643,7 @@ int os_get_win32_kern32_path(ZigWindowsSDK *sdk, Buf* output_buf, ZigLLVM_ArchTy
         buf_init_from_buf(tmp_buf, output_buf);
         buf_append_str(tmp_buf, "kernel32.lib");
         if (GetFileAttributesA(buf_ptr(tmp_buf)) != INVALID_FILE_ATTRIBUTES) {
-            return 0;
+            return ErrorNone;
         }
     }
     return ErrorFileNotFound;