[gdb/testsuite] Disallow single argument in multi_line

It's a common mistake of mine to do:
...
set l [list "foo" "bar"]
set re [multi_line $l]
...
and to get "foo bar" while I was expecting "foo\r\nbar", which I get after
doing instead:
...
set re [multi_line {*}$l]
...

Detect this type of mistake by erroring out in multi_line when only one
argument is passed.

Tested on x86_64-linux.

gdb/testsuite/ChangeLog:

2021-06-08  Tom de Vries  <tdevries@suse.de>

	* lib/gdb.exp (multi_line): Require more than one argument.
	* gdb.base/gdbinit-history.exp: Update multi_line call.
	* gdb.base/jit-reader.exp: Remove multi_line call.
	* gdb.fortran/dynamic-ptype-whatis.exp: Same.

5 files changed, 18 insertions, 5 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index e2f1486..51abd0e 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,12 @@
 2021-06-08  Tom de Vries  <tdevries@suse.de>
 
+	* lib/gdb.exp (multi_line): Require more than one argument.
+	* gdb.base/gdbinit-history.exp: Update multi_line call.
+	* gdb.base/jit-reader.exp: Remove multi_line call.
+	* gdb.fortran/dynamic-ptype-whatis.exp: Same.
+
+2021-06-08  Tom de Vries  <tdevries@suse.de>
+
 	* gdb.base/info-types.exp.tcl (match_line, gdb_test_lines): Move ...
 	* lib/gdb.exp: ... here.
 	* gdb.base/info-macros.exp: Use gdb_test_lines.
diff --git a/gdb/testsuite/gdb.base/gdbinit-history.exp b/gdb/testsuite/gdb.base/gdbinit-history.exp
index 8e3994e..36f4a11 100644
--- a/gdb/testsuite/gdb.base/gdbinit-history.exp
+++ b/gdb/testsuite/gdb.base/gdbinit-history.exp
@@ -144,7 +144,11 @@ proc check_history { hist } {
 	lappend hist_lines "    $idx  $h"
 	incr idx
     }
-    set pattern [eval multi_line $hist_lines]
+    if { [llength $hist_lines] == 1 } {
+	set pattern [lindex $hist_lines 0]
+    } else {
+	set pattern [eval multi_line $hist_lines]
+    }
 
     # Check the history.
     gdb_test "show commands" "$pattern.*"
diff --git a/gdb/testsuite/gdb.base/jit-reader.exp b/gdb/testsuite/gdb.base/jit-reader.exp
index 25d1100..83e4036 100644
--- a/gdb/testsuite/gdb.base/jit-reader.exp
+++ b/gdb/testsuite/gdb.base/jit-reader.exp
@@ -240,9 +240,7 @@ proc jit_reader_test {} {
 	# the built-in unwinder cannot backtrace through the mangled
 	# stack pointer.
 	gdb_test "bt" \
-	    [multi_line \
-		 "Backtrace stopped: Cannot access memory at address $sp_after_mangling" \
-		] \
+	    "Backtrace stopped: Cannot access memory at address $sp_after_mangling" \
 	    "bt shows error"
 
 	gdb_test "info frame" "Cannot access memory at address.*" \
diff --git a/gdb/testsuite/gdb.fortran/dynamic-ptype-whatis.exp b/gdb/testsuite/gdb.fortran/dynamic-ptype-whatis.exp
index d2ffd6d..5ea2aa4 100644
--- a/gdb/testsuite/gdb.fortran/dynamic-ptype-whatis.exp
+++ b/gdb/testsuite/gdb.fortran/dynamic-ptype-whatis.exp
@@ -73,7 +73,7 @@ gdb_test "whatis var4%t2_array" "type = Type type1, allocatable \\(3\\)"
 gdb_test "whatis var5%t3_array" "type = Type type1 \\(3\\)"
 gdb_test "whatis var6%t4_array" "type = Type type2, allocatable \\(3\\)"
 gdb_test "whatis var7%t5_array" "type = Type type2 \\(4\\)"
-gdb_test "ptype var3%t1_i" [ multi_line "type = integer\\(kind=4\\)" ]
+gdb_test "ptype var3%t1_i" "type = integer\\(kind=4\\)"
 gdb_test "ptype var4%t2_array" [ multi_line "type = Type type1" \
 				     "    integer\\(kind=4\\) :: spacer" \
 				     "    integer\\(kind=4\\) :: t1_i" \
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index f7ab219..8469ec9 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -7294,6 +7294,10 @@ proc capture_command_output { command prefix } {
 # being.
 
 proc multi_line { args } {
+    if { [llength $args] == 1 } {
+	set hint "forgot {*} before list argument?"
+	error "multi_line called with one argument ($hint)"
+    }
     return [join $args "\r\n"]
 }