commit b348d5cda89d0f4a8306056dde1c0423887854d6
author Elliott Hughes <enh@google.com> Mon Jul 24 16:53:11 2017 -0700
committer Elliott Hughes <enh@google.com> Tue Jul 25 11:54:33 2017 -0700
tree 2a9c140dc3166ebc22527373169734a9fa841582
parent 4fce647a5bcb61680c9f865b05c9f43a4841b244

Build crtbegin with clang too.

If _start_main is static, clang optimizes it out and then generates an
undefined reference from the inline assembler, so let's explicitly tell
the compiler it's used.

Bug: N/A
Test: ran tests
Change-Id: Iba3d9c63abae9a0dc32f236b01783515f0190956

libc/Android.bp

diff --git a/libc/Android.bp b/libc/Android.bp
index 842dae4..53d7d5e 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -42,6 +42,7 @@
     "-Wextra",
     "-Wunused",
     "-Wno-deprecated-declarations",
+    "-Wno-gcc-compat",
     "-Wframe-larger-than=2048",
 
     // Try to catch typical 32-bit assumptions that break with 64-bit pointers.
@@ -1912,7 +1913,7 @@
             local_include_dirs: ["arch-x86_64/include"],
         },
     },
-    clang: false,
+    clang: true,
 }
 
 cc_defaults {

libc/arch-common/bionic/crtbegin.c

diff --git a/libc/arch-common/bionic/crtbegin.c b/libc/arch-common/bionic/crtbegin.c
index d3a0f07..45c9ea7 100644
--- a/libc/arch-common/bionic/crtbegin.c
+++ b/libc/arch-common/bionic/crtbegin.c
@@ -30,16 +30,13 @@
 #include <stddef.h>
 #include <stdint.h>
 
-__attribute__((__section__(".preinit_array")))
-void (*__PREINIT_ARRAY__)(void) = (void (*)(void)) -1;
+#define SECTION(name) __attribute__((__section__(name)))
+SECTION(".preinit_array") void (*__PREINIT_ARRAY__)(void) = (void (*)(void)) -1;
+SECTION(".init_array") void (*__INIT_ARRAY__)(void) = (void (*)(void)) -1;
+SECTION(".fini_array") void (*__FINI_ARRAY__)(void) = (void (*)(void)) -1;
+#undef SECTION
 
-__attribute__((__section__(".init_array")))
-void (*__INIT_ARRAY__)(void) = (void (*)(void)) -1;
-
-__attribute__((__section__(".fini_array")))
-void (*__FINI_ARRAY__)(void) = (void (*)(void)) -1;
-
-static void _start_main(void* raw_args) {
+static void _start_main(void* raw_args) __used {
   structors_array_t array;
   array.preinit_array = &__PREINIT_ARRAY__;
   array.init_array = &__INIT_ARRAY__;