[libc] Include assert.h on baremetal targets (#83324)

Many baremetal applications use asserts.

Author: petrhosek

libc/config/baremetal/api.td

@@ -2,6 +2,42 @@ include "config/public_api.td"
 
 include "spec/stdc.td"
 
+def AssertMacro : MacroDef<"assert"> {
+  let Defn = [{
+    #undef assert
+
+    #ifdef NDEBUG
+    #define assert(e) (void)0
+    #else
+
+    #ifdef __cplusplus
+    extern "C"
+    #endif
+    _Noreturn void __assert_fail(const char *, const char *, unsigned, const char *) __NOEXCEPT;
+
+    #define assert(e)  \
+      ((e) ? (void)0 : __assert_fail(#e, __FILE__, __LINE__, __PRETTY_FUNCTION__))
+
+    #endif
+  }];
+}
+
+def StaticAssertMacro : MacroDef<"static_assert"> {
+  let Defn = [{
+    #ifndef __cplusplus
+    #undef static_assert
+    #define static_assert _Static_assert
+    #endif
+  }];
+}
+
+def AssertAPI : PublicAPI<"assert.h"> {
+  let Macros = [
+    AssertMacro,
+    StaticAssertMacro,
+  ];
+}
+
 def CTypeAPI : PublicAPI<"ctype.h"> {
 }
 

libc/config/baremetal/arm/entrypoints.txt

@@ -1,4 +1,7 @@
 set(TARGET_LIBC_ENTRYPOINTS
+    # assert.h entrypoints
+    libc.src.assert.__assert_fail
+
     # ctype.h entrypoints
     libc.src.ctype.isalnum
     libc.src.ctype.isalpha

libc/config/baremetal/arm/headers.txt

@@ -1,4 +1,5 @@
 set(TARGET_PUBLIC_HEADERS
+    libc.include.assert
     libc.include.ctype
     libc.include.fenv
     libc.include.errno

libc/config/baremetal/riscv/entrypoints.txt

@@ -1,4 +1,7 @@
 set(TARGET_LIBC_ENTRYPOINTS
+    # assert.h entrypoints
+    libc.src.assert.__assert_fail
+
     # ctype.h entrypoints
     libc.src.ctype.isalnum
     libc.src.ctype.isalpha

libc/config/baremetal/riscv/headers.txt

@@ -1,4 +1,5 @@
 set(TARGET_PUBLIC_HEADERS
+    libc.include.assert
     libc.include.ctype
     libc.include.fenv
     libc.include.errno