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[make] Build with -ffreestanding

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We should build with -ffreestanding since we are building an OS kernel and
cannot rely on all hosted environment functionality being present.
Specifically this fixes a compilation error with clang caused by the
the #include_next <limits.h>:
```
In file included from target/pc-x86/config.c:9:
In file included from dev/include/dev/driver.h:10:
In file included from lib/libc/include/sys/types.h:10:
In file included from lib/libc/include/limits.h:5:
In file included from /usr/lib/llvm-15/lib/clang/15.0.7/include/limits.h:21:
/usr/include/limits.h:26:10: fatal error: 'bits/libc-header-start.h' file not found
#include <bits/libc-header-start.h>
```
The flag fixes this issue by ensuring that __STDC_HOSTED__ is no longer set
to 1, so Clang's limits.h will not try to include the host system one.
This commit is contained in:
Alex Richardson
2023-06-07 13:25:01 -07:00
parent acb933b5ac
commit 4a9d0c33bd
1 changed files with 3 additions and 0 deletions
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3
engine.mk
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@@ -66,6 +66,9 @@ GLOBAL_COMPILEFLAGS := -g -include $(CONFIGHEADER)
GLOBAL_COMPILEFLAGS += -Wextra -Wall -Werror=return-type -Wshadow -Wdouble-promotion
GLOBAL_COMPILEFLAGS += -Wno-multichar -Wno-unused-parameter -Wno-unused-function -Wno-unused-label
GLOBAL_COMPILEFLAGS += -fno-common
# Build with -ffreestanding since we are building an OS kernel and cannot
# rely on all hosted environment functionality being present.
GLOBAL_COMPILEFLAGS += -ffreestanding
GLOBAL_CFLAGS := --std=gnu11 -Werror-implicit-function-declaration -Wstrict-prototypes -Wwrite-strings
GLOBAL_CPPFLAGS := --std=c++14 -fno-exceptions -fno-rtti -fno-threadsafe-statics
GLOBAL_ASMFLAGS := -DASSEMBLY