target_read_memory&co: no longer return target_xfer_status

Years ago, these functions used to return errno/EIO.  Later, through a
series of changes that intended to remove native/remote differences,
they ended up returning a target_xfer_status in disguise.

Unlike target_xfer_partial&co, the point of target_read_memory&co is
to either fully succeed or fail.  On error, they always return
TARGET_XFER_E_IO.  So there's no real point in casting the return of
target_read_memory to a target_xfer_status to pass it to memory_error.
Instead, it results in clearer code to simply decouple
target_read_memory&co's return from target_xfer_status.

This fixes build errors like this in C++ mode:

 ../../src/gdb/corefile.c: In function ‘void read_stack(CORE_ADDR, gdb_byte*, ssize_t)’:
 ../../src/gdb/corefile.c:276:34: error: invalid conversion from ‘int’ to ‘target_xfer_status’ [-fpermissive]
      memory_error (status, memaddr);
				   ^
 ../../src/gdb/corefile.c:216:1: error:   initializing argument 1 of ‘void memory_error(target_xfer_status, CORE_ADDR)’ [-fpermissive]

gdb/ChangeLog:
2015-10-27  Pedro Alves  <palves@redhat.com>

	* alpha-tdep.c (alpha_read_insn): Always pass TARGET_XFER_E_IO to
	memory_error.  Rename local 'status' to 'res'.
	* c-lang.c (c_get_string): Always pass TARGET_XFER_E_IO to
	memory_error.
	* corefile.c (read_stack, read_code, write_memory): Always pass
	TARGET_XFER_E_IO to memory_error.
	* disasm.c (dis_asm_memory_error): Always pass TARGET_XFER_E_IO to
	memory_error.  Rename parameter 'status' to 'err'.
	(dump_insns): Rename local 'status' to 'err'.
	* mips-tdep.c (mips_fetch_instruction): Rename parameter 'statusp'
	to 'errp'.  Rename local 'status' to 'err'.  Always pass
	TARGET_XFER_E_IO to memory_error.
	(mips_breakpoint_from_pc): Rename local 'status' to 'err'.
	* target.c (target_read_memory, target_read_raw_memory)
	(target_read_stack, target_read_code, target_write_memory)
	(target_write_raw_memory): Return -1 on error instead of
	TARGET_XFER_E_IO.
	* valprint.c (val_print_string): Rename local 'errcode' to 'err'.
	Always pass TARGET_XFER_E_IO to memory_error.  Update comment.

1 files changed, 6 insertions, 6 deletions

diff --git a/gdb/disasm.c b/gdb/disasm.c
index 6e3d6c1d0b..c17574ebee 100644
--- a/gdb/disasm.c
+++ b/gdb/disasm.c
@@ -129,10 +129,10 @@ dis_asm_read_memory (bfd_vma memaddr, gdb_byte *myaddr, unsigned int len,
 
 /* Like memory_error with slightly different parameters.  */
 static void
-dis_asm_memory_error (int status, bfd_vma memaddr,
+dis_asm_memory_error (int err, bfd_vma memaddr,
 		      struct disassemble_info *info)
 {
-  memory_error (status, memaddr);
+  memory_error (TARGET_XFER_E_IO, memaddr);
 }
 
 /* Like print_address with slightly different parameters.  */
@@ -230,7 +230,7 @@ dump_insns (struct gdbarch *gdbarch, struct ui_out *uiout,
         {
           CORE_ADDR old_pc = pc;
           bfd_byte data;
-          int status;
+          int err;
           const char *spacer = "";
 
           /* Build the opcodes using a temporary stream so we can
@@ -242,9 +242,9 @@ dump_insns (struct gdbarch *gdbarch, struct ui_out *uiout,
           pc += gdbarch_print_insn (gdbarch, pc, di);
           for (;old_pc < pc; old_pc++)
             {
-              status = (*di->read_memory_func) (old_pc, &data, 1, di);
-              if (status != 0)
-                (*di->memory_error_func) (status, old_pc, di);
+              err = (*di->read_memory_func) (old_pc, &data, 1, di);
+              if (err != 0)
+                (*di->memory_error_func) (err, old_pc, di);
               fprintf_filtered (opcode_stream, "%s%02x",
                                 spacer, (unsigned) data);
               spacer = " ";