[pushed] Darwin, Driver: Avoid a link line for empty commands.

[pushed] Darwin, Driver: Avoid a link line for empty commands.

[Iain Sandoe]

We were pushing a spec value for weak_reference_mismatches unconditionally
which is not needed (the value was the default) and the side-effect of
this was that we appeared to need to drive a link command; leading to
unexpected diagnostics for cases where gcc was invoked with an empty
command line.

Also we were pushing flags for sysroot, os minimum version and controls
even if the command line was empty.

tested on x86_64, i686 and powerpc-darwin, pushed to master, thanks
Iain

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>

gcc/ChangeLog:

	* config/darwin-driver.c (darwin_driver_init): Exit from the
	option handling early if the command line is definitely enpty.
	* config/darwin.h (SUBTARGET_DRIVER_SELF_SPECS): Remove
	setting for the default content of weak_reference_mismatches.
---
 gcc/config/darwin-driver.c | 8 ++++++--
 gcc/config/darwin.h        | 5 -----
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/gcc/config/darwin-driver.c b/gcc/config/darwin-driver.c
index 7fa80abc314..688fe8fabc0 100644
--- a/gcc/config/darwin-driver.c
+++ b/gcc/config/darwin-driver.c
@@ -416,6 +416,10 @@ darwin_driver_init (unsigned int *decoded_options_count,
     }
 #endif
 
+  /* If there is nothing else on the command line, do not add sysroot etc.  */
+  if (*decoded_options_count <= 1)
+    return;
+
   if (appendM32 || appendM64)
     {
       ++*decoded_options_count;
@@ -426,7 +430,7 @@ darwin_driver_init (unsigned int *decoded_options_count,
 		       &(*decoded_options)[*decoded_options_count - 1]);
     }
 
-  if (! seen_sysroot_p)
+  if (!seen_sysroot_p)
     {
       /* We will pick up an SDKROOT if we didn't specify a sysroot and treat
 	 it as overriding any configure-time --with-sysroot.  */
@@ -445,7 +449,7 @@ darwin_driver_init (unsigned int *decoded_options_count,
   /* We will need to know the OS X version we're trying to build for here
      so that we can figure out the mechanism and source for the sysroot to
      be used.  */
-  if (! seen_version_min && *decoded_options_count > 1)
+  if (!seen_version_min)
     /* Not set by the User, try to figure it out.  */
     vers_string = darwin_default_min_version ();
 
diff --git a/gcc/config/darwin.h b/gcc/config/darwin.h
index 0ce13207ad6..75b688ebf9e 100644
--- a/gcc/config/darwin.h
+++ b/gcc/config/darwin.h
@@ -268,11 +268,6 @@ extern GTY(()) int darwin_ms_struct;
   "%{unexported_symbols_list*:\
      -Xlinker -unexported_symbols_list -Xlinker %*} \
      %<unexported_symbols_list*",					\
-  "%{!weak_reference_mismatches*:\
-     %:version-compare(< 10.5 asm_macosx_version_min= -Xlinker) \
- %:version-compare(< 10.5 asm_macosx_version_min= -weak_reference_mismatches) \
-     %:version-compare(< 10.5 asm_macosx_version_min= -Xlinker) \
-     %:version-compare(< 10.5 asm_macosx_version_min= non-weak)}",	\
   "%{weak_reference_mismatches*:\
     -Xlinker -weak_reference_mismatches -Xlinker %*} \
     %<weak_reference_mismatches*",					\
-- 
2.24.3 (Apple Git-128)