[PATCHv2 1/2] gdb/guile: perform tilde expansion when sourcing guile scripts

[Andrew Burgess <andrew.burgess@embecosm.com>]

Before this patch:

  (gdb) source ~/script.scm
  ERROR: In procedure apply-smob/1:
  ERROR: In procedure primitive-load-path: Unable to find file "~/script.scm" in load path
  Error while executing Scheme code.
  (gdb)

This is because the path is not tilde expanded.  In contrast, when
sourcing a .py or .gdb script the path is tilde expanded.

This commit fixes this oversight, and allows the above source command
to work as expected.

The tilde expansion is done in guile/scm-safe-call.c rather than at a
higher level, for example, it might be tempting to add the tilde
expansion in cli/cli-cmds.c:source_script_from_stream, however, not
every extension language wants to see a tilde expanded file path.  For
example, consider Python.  Currently we pass in an unexpanded path and
we see this behaviour:

  (gdb) source ~/tmp/xxx.py
  Traceback (most recent call last):
    File "~/tmp/xxx.py", line 1, in <module>
  NameError: name 'undefined' is not defined

If we performed tilde expansion prior to calling the Python sourcer
function (gdbpy_source_script), we would instead see:

  (gdb) source ~/tmp/xxx.py
  Traceback (most recent call last):
    File "/home/andrew/tmp/xxx.py", line 1, in <module>
      undefined
  NameError: name 'undefined' is not defined

Notice the path expansion in the second line of the error message, I
believe this is a change for the worse.

And so, I think the best solution is for each language to perform its
own tilde expansion if this is required, i.e. if the underlying
language engine does not already handle tilde expansion.

gdb/ChangeLog:

	* guile/scm-safe-call.c: Add 'gdbsupport/gdb_tilde_expand.h'
	include.
	(gdbscm_safe_source_script): Perform tilde expansion if the path
	is not absolute.

gdb/testsuite/ChangeLog:

	* gdb.guile/guile.exp: Add an extra test.
---
 gdb/ChangeLog                     | 7 +++++++
 gdb/guile/scm-safe-call.c         | 4 +++-
 gdb/testsuite/ChangeLog           | 4 ++++
 gdb/testsuite/gdb.guile/guile.exp | 7 +++++++
 4 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/gdb/guile/scm-safe-call.c b/gdb/guile/scm-safe-call.c
index 2a38d6331fb..5bea970239b 100644
--- a/gdb/guile/scm-safe-call.c
+++ b/gdb/guile/scm-safe-call.c
@@ -24,6 +24,7 @@
 #include "filenames.h"
 #include "guile-internal.h"
 #include "gdbsupport/pathstuff.h"
+#include "gdbsupport/gdb_tilde_expand.h"
 
 /* Struct to marshall args to scscm_safe_call_body.  */
 
@@ -444,7 +445,8 @@ gdbscm_safe_source_script (const char *filename)
 
   if (!IS_ABSOLUTE_PATH (filename))
     {
-      abs_filename = gdb_realpath (filename);
+      abs_filename = gdb_tilde_expand_up (filename);
+      abs_filename = gdb_realpath (abs_filename.get ());
       filename = abs_filename.get ();
     }
 
diff --git a/gdb/testsuite/gdb.guile/guile.exp b/gdb/testsuite/gdb.guile/guile.exp
index 6e464cc0e77..0fb82284f46 100644
--- a/gdb/testsuite/gdb.guile/guile.exp
+++ b/gdb/testsuite/gdb.guile/guile.exp
@@ -82,3 +82,10 @@ gdb_test_no_output "guile (define a (execute \"help\" #:to-string #t))" \
 
 gdb_test "guile (print a)" "= .*aliases -- User-defined aliases of other commands.*" \
     "verify help to uiout"
+
+# Verify that we can source a guile script using ~ for the HOME directory.
+save_vars { env(HOME) } {
+    set env(HOME) $srcdir/$subdir
+    clean_restart
+    gdb_test "source ~/source2.scm" "yes"
+}
-- 
2.25.4