Fix solink and add a postsolink hook (use the hook for android strip)

build/toolchain/gcc_toolchain.gni

Index: build/toolchain/gcc_toolchain.gni
diff --git a/build/toolchain/gcc_toolchain.gni b/build/toolchain/gcc_toolchain.gni
index 9ad47a4900ee8b84f68f7aa90852602590e41189..6cbcfec824f954bc43e775441d6baad07123006d 100644
--- a/build/toolchain/gcc_toolchain.gni
+++ b/build/toolchain/gcc_toolchain.gni
@@ -80,10 +80,22 @@ template("gcc_toolchain") {
       rspfile_content = "\$in"
     }
     tool("solink") {
-      command = "if [ ! -e \$lib -o ! -e \${lib}.TOC ]; then $ld -shared \$ldflags -o \$lib -Wl,-soname=\$soname @\$rspfile && { readelf -d \${lib} | grep SONAME ; nm -gD -f p \${lib} | cut -f1-2 -d' '; } > \${lib}.TOC; else $ld -shared \$ldflags -o \$lib -Wl,-soname=\$soname -Wl,--whole-archive \$in \$solibs -Wl,--no-whole-archive $libs_section_prefix \$libs $libs_section_postfix && { readelf -d \${lib} | grep SONAME ; nm -gD -f p \${lib} | cut -f1-2 -d' '; } > \${lib}.tmp && if ! cmp -s \${lib}.tmp \${lib}.TOC; then mv \${lib}.tmp \${lib}.TOC ; fi; fi"
-      description = "SOLINK \$lib"
       rspfile = "\$out.rsp"
-      rspfile_content = "-Wl,--whole-archive \$in \$solibs -Wl,--no-whole-archive \$libs"
+      rspfile_content = "-Wl,--whole-archive \$in \$solibs -Wl,--no-whole-archive $libs_section_prefix \$libs $libs_section_postfix"
+
+      # TODO(cjhopman): There needs to be a way for gn to correctly figure out
+      # the outputs of a solink command.

[cjhopman, 2014/07/07 23:00:50]

Currently, it looks like gn doesn't know about the .TOC output at all. I don't
know what the plan for that is. That is more complicated then just specifying it
as an output of these actions, though, since it should actually be used as the
inputs to other libraries (instead of the .so file).

Still, if there is no way for this "tool" to specify its outputs, then there's
no good way for the postsolink hook below to add outputs (or rather, there's no
way for ninja to know about such added outputs).

[brettw, 2014/07/08 22:06:54]

I don't know the plan for this either, something we need to figure out.
Currently the outputs and such are hardcoded.

+
+      link_command = "$ld -shared \$ldflags -o \$lib -Wl,-soname=\$soname $rspfile_content"
+      toc_command = "{ readelf -d \${lib} | grep SONAME ; nm -gD -f p \${lib} | cut -f1-2 -d' '; } > \${lib}.tmp"
+      replace_command = "if ! cmp -s \${lib}.tmp \${lib}.TOC; then mv \${lib}.tmp \${lib}.TOC; fi"
+      command = "$link_command && $toc_command && $replace_command"

[cjhopman, 2014/07/07 23:00:50]

This is slightly different from the previous version. That one would be
something like:

$if_not_exists; then $link_command && $toc_command > \${lib}.TOC; else
$link_command && $toc_command > \${lib}.tmp && replace_command; fi

Afaict, `cmp` will fail if a file doesn't exist and so there isn't really a need
for the if/else.

It's possible that there is some platform where this doesn't do what I expect,
though (mac maybe?).

+
+      if (defined(invoker.postsolink)) {

[brettw, 2014/07/08 22:06:54]

Can you add the extra stuff you added to the optional parameters documentation
above?

+        command += " && " + invoker.postsolink
+      }
+
+      description = "SOLINK \$lib"
       #pool = "link_pool"
       restat = "1"
     }