I finally fixed it, with help of a friend. First I tried a workaround where I tried to link V8 as a shared library, which didn't turn out well because the NDK native activity interface I'm using turned out to be incompatible with loading additional shared objects.
There were two different issues going on with my static libraries. The first and most important one is that the static libraries built by V8 are not suitable for linking. You can check this by using:
ar x [static_library.a]
which will normally extract the *.o objects from the library. In this case, it reported:
`x' cannot be used on thin archives
A thin archive is just a set of references to the absolute paths of the *.o files, and no actual content. That explains why my build stopped working at one point where I moved or deleted the original *.o files from the V8 build tree. Strangely, the linker kept silent about that.
Creating static libraries is not currently a build option in V8. Thankfully, this guy has a patch for creating proper static libraries in V8.
The app still didn't link after I did that, because I copied the wrong files the first time round. As it turned out, the static libraries are also built for the host architecture (don't ask me why), and I accidentally copied those. I learned that you can use:
file objectfile.o
to see what architecture it is. Hence I found my static libraries were i386 and not arm. So, the linker was skipping these files, because the architecture didn't match (you can mix architectures in a static library).
Here is the V8 patch that I made to V8 3.27.28 based on the patch by Curu Wong. I will try to get this patch committed. Patch 1:
~/Work/javascript/Engines/v8-trunk/tools/gyp$ diff -u v8.gyp.orig v8.gyp
--- v8.gyp.orig 2014-06-18 21:09:59.368336736 +0200
+++ v8.gyp 2014-06-18 21:12:20.264331660 +0200
@@ -108,6 +108,7 @@
{
'target_name': 'v8_snapshot',
'type': 'static_library',
+ 'standalone_static_library': 1,
'conditions': [
['want_separate_host_toolset==1', {
'toolsets': ['host', 'target'],
@@ -180,6 +181,7 @@
{
'target_name': 'v8_nosnapshot',
'type': 'static_library',
+ 'standalone_static_library': 1,
'dependencies': [
'v8_base',
],
@@ -237,6 +239,7 @@
{
'target_name': 'v8_base',
'type': 'static_library',
+ 'standalone_static_library': 1,
'dependencies': [
'v8_libbase.<(v8_target_arch)',
],
Patch 2:
~/Work/javascript/Engines/v8-trunk/third_party/icu$ diff -u icu.gyp.orig icu.gyp
--- icu.gyp.orig 2014-06-18 21:10:22.060335920 +0200
+++ icu.gyp 2014-06-18 21:15:06.468325674 +0200
@@ -56,6 +56,7 @@
{
'target_name': 'icudata',
'type': 'static_library',
+ 'standalone_static_library': 1,
'defines': [
'U_HIDE_DATA_SYMBOL',
],
@@ -141,6 +142,11 @@
{
'target_name': 'icui18n',
'type': '<(component)',
+ 'conditions': [
+ [ 'component!="shared_library"', {
+ 'standalone_static_library': 1,
+ }],
+ ],
'sources': [
'<@(icui18n_sources)',
],
@@ -241,6 +247,11 @@
{
'target_name': 'icuuc',
'type': '<(component)',
+ 'conditions': [
+ [ 'component!="shared_library"', {
+ 'standalone_static_library': 1,
+ }],
+ ],
'sources': [
'<@(icuuc_sources)',
],
