[RFC,gdb/testsuite] Add -lbl option in gdb_test_multiple

[gdb/testsuite] Add -lbl option in gdb_test_multiple

Add gdb_test_multiple option -lbl, that adds a regexp after the user code that
reads one line, and discards it:
...
           -re "\r\n\[^\r\n\]*(?=\r\n)" {
               exp_continue
           }
...

In order to be able to write:
...
gdb_test_multiple "command" "testname" -lbl {
  ...
}
...
rewrite the promp_regexp argument usage into the similar:
...
gdb_test_multiple "command" "testname" -prompt $prompt_regexp {
  ...
}
...

Build and reg-tested on x86_64-linux.

Tested gdb.base/corefile-buildid.exp with both make targets check and
check-read1.

gdb/testsuite/ChangeLog:

2020-02-2120  Pedro Alves  <palves@redhat.com>
	      Tom de Vries  <tdevries@suse.de>

	* lib/gdb.exp (gdb_test_multiple): Handle prompt_regexp option using
	-prompt prefix, before user_code argument.  Add -lbl option likewise.
	(skip_python_tests_prompt, skip_libstdcxx_probe_tests_prompt)
	(gdb_is_target_1): Add -prompt prefix and move to before user_code
	argument.
	* gdb.base/corefile-buildid.exp: Use -lbl option.  Rewrite regexps to
	have "\r\n" at start-of-line, instead of at end-of-line.

---
 gdb/testsuite/gdb.base/corefile-buildid.exp | 27 ++------
 gdb/testsuite/lib/gdb.exp                   | 98 +++++++++++++++++++----------
 2 files changed, 72 insertions(+), 53 deletions(-)

diff --git a/gdb/testsuite/gdb.base/corefile-buildid.exp b/gdb/testsuite/gdb.base/corefile-buildid.exp
index b9844ee354..e24562dedb 100644
--- a/gdb/testsuite/gdb.base/corefile-buildid.exp
+++ b/gdb/testsuite/gdb.base/corefile-buildid.exp
@@ -113,17 +113,11 @@  proc check_exec_file {file} {
 
     # Get line with "Local exec file:".
     set ok 0
-    gdb_test_multiple "info files" "" {
-	-re "^Local exec file:\r\n" {
+    gdb_test_multiple "info files" "" -lbl {
+	-re "\r\nLocal exec file:" {
 	    set test_name $gdb_test_name
 	    set ok 1
 	}
-	-re "^$gdb_prompt $" {
-	    fail $gdb_test_name
-	}
-	-re "^\[^\r\n\]*\r\n" {
-	    exp_continue
-	}
     }
 
     if { $ok == 0 } {
@@ -132,16 +126,10 @@  proc check_exec_file {file} {
 
     # Get subsequent line with $file.
     set ok 0
-    gdb_test_multiple "" $test_name {
-	-re "^\[\t\ \]+`[string_to_regexp $file]'\[^\r\n\]*\r\n" {
+    gdb_test_multiple "" $test_name -lbl {
+	-re "\r\n\[\t\ \]+`[string_to_regexp $file]'\[^\r\n\]*" {
 	    set ok 1
 	}
-	-re "^$gdb_prompt $" {
-	    fail $gdb_test_name
-	}
-	-re "^\[^\r\n\]*\r\n" {
-	    exp_continue
-	}
     }
 
     if { $ok == 0 } {
@@ -149,13 +137,10 @@  proc check_exec_file {file} {
     }
 
     # Skip till prompt.
-    gdb_test_multiple "" $test_name {
-	-re "^$gdb_prompt $" {
+    gdb_test_multiple "" $test_name -lbl {
+	-re "\r\n$gdb_prompt $" {
 	    pass $gdb_test_name
 	}
-	-re "^\[^\r\n\]*\r\n" {
-	    exp_continue
-	}
     }
 }
 
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 26795d0152..ab22f24436 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -698,20 +698,22 @@  proc gdb_internal_error_resync {} {
 }
 
 
-# gdb_test_multiple COMMAND MESSAGE EXPECT_ARGUMENTS PROMPT_REGEXP
+# gdb_test_multiple COMMAND MESSAGE [ -promp PROMPT_REGEXP] [ -lbl ]
+#                   EXPECT_ARGUMENTS
 # Send a command to gdb; test the result.
 #
 # COMMAND is the command to execute, send to GDB with send_gdb.  If
 #   this is the null string no command is sent.
 # MESSAGE is a message to be printed with the built-in failure patterns
 #   if one of them matches.  If MESSAGE is empty COMMAND will be used.
+# -prompt PROMPT_REGEXP specifies a regexp matching the expected prompt
+#   after the command output.  If empty, defaults to "$gdb_prompt $".
+# -lbl specifies that line-by-line matching will be used.
 # EXPECT_ARGUMENTS will be fed to expect in addition to the standard
 #   patterns.  Pattern elements will be evaluated in the caller's
 #   context; action elements will be executed in the caller's context.
 #   Unlike patterns for gdb_test, these patterns should generally include
 #   the final newline and prompt.
-# PROMPT_REGEXP is a regexp matching the expected prompt after the command
-#   output.  If empty, defaults to "$gdb_prompt $"
 #
 # Returns:
 #    1 if the test failed, according to a built-in failure pattern
@@ -791,7 +793,7 @@  proc gdb_internal_error_resync {} {
 #	}
 #    }
 #
-proc gdb_test_multiple { command message user_code { prompt_regexp "" } } {
+proc gdb_test_multiple { command message args } {
     global verbose use_gdb_stub
     global gdb_prompt pagination_prompt
     global GDB
@@ -801,6 +803,26 @@  proc gdb_test_multiple { command message user_code { prompt_regexp "" } } {
     upvar expect_out expect_out
     global any_spawn_id
 
+    set line_by_line 0
+    set prompt_regexp ""
+    for {set i 0} {$i < [llength $args]} {incr i} {
+	set arg [lindex $args $i]
+	if { $arg  == "-prompt" } {
+	    incr i
+	    set prompt_regexp [lindex $args $i]
+	} elseif { $arg == "-lbl" } {
+	    set line_by_line 1
+	} else {
+	    set user_code $arg
+	    break
+	}
+    }
+    if { [expr $i + 1] < [llength $args] } {
+	error "Too many arguments to gdb_test_multiple"
+    } elseif { ![info exists user_code] } {
+	error "Too few arguments to gdb_test_multiple"
+    }
+
     if { "$prompt_regexp" == "" } {
 	set prompt_regexp "$gdb_prompt $"
     }
@@ -1069,6 +1091,14 @@  proc gdb_test_multiple { command message user_code { prompt_regexp "" } } {
 	}
     }
 
+    if {$line_by_line} {
+       append code {
+           -re "\r\n\[^\r\n\]*(?=\r\n)" {
+               exp_continue
+           }
+       }
+    }
+
     # Now patterns that apply to any spawn id specified.
     append code {
 	-i $any_spawn_id
@@ -1996,22 +2026,24 @@  proc skip_rust_tests {} {
 proc skip_python_tests_prompt { prompt_regexp } {
     global gdb_py_is_py3k
 
-    gdb_test_multiple "python print ('test')" "verify python support" {
-	-re "not supported.*$prompt_regexp" {
-	    unsupported "Python support is disabled."
-	    return 1
+    gdb_test_multiple "python print ('test')" "verify python support" \
+	-prompt "$prompt_regexp" {
+	    -re "not supported.*$prompt_regexp" {
+		unsupported "Python support is disabled."
+		return 1
+	    }
+	    -re "$prompt_regexp" {}
 	}
-	-re "$prompt_regexp" {}
-    } "$prompt_regexp"
 
-    gdb_test_multiple "python print (sys.version_info\[0\])" "check if python 3" {
-	-re "3.*$prompt_regexp" {
-            set gdb_py_is_py3k 1
-        }
-	-re ".*$prompt_regexp" {
-            set gdb_py_is_py3k 0
-        }
-    } "$prompt_regexp"
+    gdb_test_multiple "python print (sys.version_info\[0\])" "check if python 3" \
+	-prompt "$prompt_regexp" {
+	    -re "3.*$prompt_regexp" {
+		set gdb_py_is_py3k 1
+	    }
+	    -re ".*$prompt_regexp" {
+		set gdb_py_is_py3k 0
+	    }
+	}
 
     return 0
 }
@@ -3265,13 +3297,14 @@  proc skip_unwinder_tests {} {
 
 proc skip_libstdcxx_probe_tests_prompt { prompt_regexp } {
     set supported 0
-    gdb_test_multiple "info probe" "check for stap probe in libstdc++" {
-	-re ".*libstdcxx.*catch.*\r\n$prompt_regexp" {
-	    set supported 1
-	}
-	-re "\r\n$prompt_regexp" {
+    gdb_test_multiple "info probe" "check for stap probe in libstdc++" \
+	-prompt "$prompt_regexp" {
+	    -re ".*libstdcxx.*catch.*\r\n$prompt_regexp" {
+		set supported 1
+	    }
+	    -re "\r\n$prompt_regexp" {
+	    }
 	}
-    } "$prompt_regexp"
     set skip [expr !$supported]
     return $skip
 }
@@ -3311,15 +3344,16 @@  proc skip_compile_feature_tests {} {
 
 proc gdb_is_target_1 { target_name target_stack_regexp prompt_regexp } {
     set test "probe for target ${target_name}"
-    gdb_test_multiple "maint print target-stack" $test {
-	-re "${target_stack_regexp}${prompt_regexp}" {
-	    pass $test
-	    return 1
-	}
-	-re "$prompt_regexp" {
-	    pass $test
+    gdb_test_multiple "maint print target-stack" $test \
+	-prompt "$prompt_regexp" {
+	    -re "${target_stack_regexp}${prompt_regexp}" {
+		pass $test
+		return 1
+	    }
+	    -re "$prompt_regexp" {
+		pass $test
+	    }
 	}
-    } "$prompt_regexp"
     return 0
 }