tests: update `x' quotes to 'x' to match gnulib outputs.

In the (extremely!) long time since this branch was last active,
GNU is moving towards upright quotes exclusively, including
several of the files we use from gnulib -- which breaks many of
the test cases.
* doc/m4.texi: Fix quotes in many example tests extracted to
tests/generated.m4.
* tests/builtins.at, tests/freeze.at, tests/macros.at,
tests/modules.at, tests/null.at, tests/options.at,
tests/others.at: Fix quotes in many expected output comparisons.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>

8 files changed, 84 insertions, 84 deletions

diff --git a/doc/m4.texi b/doc/m4.texi
index fa0c6fda..b42a1f41 100644
--- a/doc/m4.texi
+++ b/doc/m4.texi
@@ -661,7 +661,7 @@ a warning.
 @example
 $ @kbd{m4}
 defn(`oops')
-@error{}m4:stdin:1: warning: defn: undefined macro `oops'
+@error{}m4:stdin:1: warning: defn: undefined macro 'oops'
 @result{}
 ^D
 @end example
@@ -691,7 +691,7 @@ $ @kbd{echo $?}
 @example
 $ @kbd{m4 -E -d}
 defn(`oops')
-@error{}m4:stdin:1: warning: defn: undefined macro `oops'
+@error{}m4:stdin:1: warning: defn: undefined macro 'oops'
 @result{}
 ^D
 @end example
@@ -2257,7 +2257,7 @@ m4}).
 @example
 $ @kbd{m4}
 undefine(`a')
-@error{}m4:stdin:1: warning: undefine: undefined macro `a'
+@error{}m4:stdin:1: warning: undefine: undefined macro 'a'
 @result{}
 debugmode(`-d')
 @result{}
@@ -2460,7 +2460,7 @@ builtin token does not occur in isolation.  A future version of
 @example
 $ @kbd{m4 -d}
 defn(`foo')
-@error{}m4:stdin:1: warning: defn: undefined macro `foo'
+@error{}m4:stdin:1: warning: defn: undefined macro 'foo'
 @result{}
 debugmode(`-d')
 @result{}
@@ -2610,7 +2610,7 @@ define(`a', `1')
 popdef
 @result{}popdef
 popdef(`a', `a')
-@error{}m4:stdin:3: warning: popdef: undefined macro `a'
+@error{}m4:stdin:3: warning: popdef: undefined macro 'a'
 @result{}
 debugmode(`-d')
 @result{}
@@ -2785,7 +2785,7 @@ f(define(`f', `2'))
 indir(`f', define(`f', `3'))
 @result{}3
 indir(`f', undefine(`f'))
-@error{}m4:stdin:4: warning: indir: undefined macro `f'
+@error{}m4:stdin:4: warning: indir: undefined macro 'f'
 @result{}
 debugmode(`-d')
 @result{}
@@ -2896,10 +2896,10 @@ $ @kbd{m4 -P}
 m4_builtin(`divnum')
 @result{}0
 m4_builtin(`m4_divnum')
-@error{}m4:stdin:2: warning: m4_builtin: undefined builtin `m4_divnum'
+@error{}m4:stdin:2: warning: m4_builtin: undefined builtin 'm4_divnum'
 @result{}
 m4_indir(`divnum')
-@error{}m4:stdin:3: warning: m4_indir: undefined macro `divnum'
+@error{}m4:stdin:3: warning: m4_indir: undefined macro 'divnum'
 @result{}
 m4_indir(`m4_divnum')
 @result{}0
@@ -2918,17 +2918,17 @@ as though empty strings had been passed as the required arguments.
 builtin
 @result{}builtin
 builtin()
-@error{}m4:stdin:2: warning: builtin: undefined builtin `'
+@error{}m4:stdin:2: warning: builtin: undefined builtin ''
 @result{}
 builtin(`builtin')
 @error{}m4:stdin:3: warning: builtin: too few arguments: 0 < 1
 @result{}
 builtin(`builtin',)
-@error{}m4:stdin:4: warning: builtin: undefined builtin `'
+@error{}m4:stdin:4: warning: builtin: undefined builtin ''
 @result{}
 builtin(`builtin', ``'
 ')
-@error{}m4:stdin:5: warning: builtin: undefined builtin ``\'\n'
+@error{}m4:stdin:5: warning: builtin: undefined builtin '`\'\n'
 @result{}
 indir(`index')
 @error{}m4:stdin:7: warning: index: too few arguments: 0 < 2
@@ -2988,7 +2988,7 @@ traceoff
 changequote(`[', `]')
 @result{}
 defn1([foo])
-@error{}m4:stdin:11: warning: builtin: undefined builtin ``defn\''
+@error{}m4:stdin:11: warning: builtin: undefined builtin '`defn\''
 @result{}
 defn2([foo])
 @result{}bar
@@ -2999,7 +2999,7 @@ defn1([foo])
 changequote
 @result{}
 defn1(`foo')
-@error{}m4:stdin:16: warning: builtin: undefined builtin `[defn]'
+@error{}m4:stdin:16: warning: builtin: undefined builtin '[defn]'
 @result{}
 @end example
 
@@ -4120,7 +4120,7 @@ f(popdef(`f')dumpdef(`f'))
 @error{}f:@tabchar{}``$0'1'
 @result{}f2
 f(popdef(`f')dumpdef(`f'))
-@error{}m4:stdin:3: warning: dumpdef: undefined macro `f'
+@error{}m4:stdin:3: warning: dumpdef: undefined macro 'f'
 @result{}f1
 debugmode(`-d')
 @result{}
@@ -4244,17 +4244,17 @@ traceon(`foo')
 foo
 @result{}foo
 defn(`foo')
-@error{}m4:stdin:4: warning: defn: undefined macro `foo'
+@error{}m4:stdin:4: warning: defn: undefined macro 'foo'
 @result{}
 undefine(`foo')
-@error{}m4:stdin:5: warning: undefine: undefined macro `foo'
+@error{}m4:stdin:5: warning: undefine: undefined macro 'foo'
 @result{}
 pushdef(`foo')
 @result{}
 popdef(`foo')
 @result{}
 popdef(`foo')
-@error{}m4:stdin:8: warning: popdef: undefined macro `foo'
+@error{}m4:stdin:8: warning: popdef: undefined macro 'foo'
 @result{}
 define(`foo', `bar')
 @result{}
@@ -4266,7 +4266,7 @@ undefine(`foo')
 ifdef(`foo', `yes', `no')
 @result{}no
 indir(`foo')
-@error{}m4:stdin:13: warning: indir: undefined macro `foo'
+@error{}m4:stdin:13: warning: indir: undefined macro 'foo'
 @result{}
 define(`foo', `blah')
 @result{}
@@ -4619,13 +4619,13 @@ to macro tracing.
 @comment options: -dip
 @example
 $ @kbd{m4 -dip -I examples}
-@error{}m4debug: input read from `stdin'
+@error{}m4debug: input read from 'stdin'
 define(`foo', `m4wrap(`wrapped text
 ')dnl')
 @result{}
 include(`incl.m4')dnl
-@error{}m4debug: path search for `incl.m4' found `examples/incl.m4'
-@error{}m4debug: input read from `examples/incl.m4'
+@error{}m4debug: path search for 'incl.m4' found 'examples/incl.m4'
+@error{}m4debug: input read from 'examples/incl.m4'
 @result{}Include file start
 @result{}Include file end
 @error{}m4debug: input reverted to stdin, line 3
@@ -4676,7 +4676,7 @@ Also, the special tokens for builtin functions are not truncated.
 @example
 $ @kbd{m4 -d -l 6 -t echo -t defn}
 debuglen(`oops')
-@error{}m4:stdin:1: warning: debuglen: non-numeric argument `oops'
+@error{}m4:stdin:1: warning: debuglen: non-numeric argument 'oops'
 @result{}
 define(`echo', `$@@')
 @result{}
@@ -5364,7 +5364,7 @@ changeresyntax(`GNU-m4')
 changeresyntax(`Gnu_M4')
 @result{}
 changeresyntax(`unknown')
-@error{}m4:stdin:4: warning: changeresyntax: bad syntax-spec: `unknown'
+@error{}m4:stdin:4: warning: changeresyntax: bad syntax-spec: 'unknown'
 @result{}
 @end example
 
@@ -6010,10 +6010,10 @@ parameters.
 @comment status: 1
 @example
 include(`n')
-@error{}m4:stdin:1: include: cannot open `n': No such file or directory
+@error{}m4:stdin:1: include: cannot open 'n': No such file or directory
 @result{}
 include()
-@error{}m4:stdin:2: include: cannot open `': No such file or directory
+@error{}m4:stdin:2: include: cannot open '': No such file or directory
 @result{}
 sinclude(`n')
 @result{}
@@ -7547,14 +7547,14 @@ Likewise, escape sequences are not yet recognized.
 
 @example
 format(`%p', `0')
-@error{}m4:stdin:1: warning: format: unrecognized specifier in `%p'
+@error{}m4:stdin:1: warning: format: unrecognized specifier in '%p'
 @result{}p
 format(`%*d', `')
 @error{}m4:stdin:2: warning: format: empty string treated as 0
 @error{}m4:stdin:2: warning: format: too few arguments: 2 < 3
 @result{}0
 format(`%.1f', `2a')
-@error{}m4:stdin:3: warning: format: non-numeric argument `2a'
+@error{}m4:stdin:3: warning: format: non-numeric argument '2a'
 @result{}2.0
 @end example
 
@@ -7710,23 +7710,23 @@ eval(`(1 | 1) ^ 1')
 eval(`+ + - ~ ! ~ 0')
 @result{}1
 eval(`++0')
-@error{}m4:stdin:8: warning: eval: invalid operator: `++0'
+@error{}m4:stdin:8: warning: eval: invalid operator: '++0'
 @result{}
 eval(`1 = 1')
-@error{}m4:stdin:9: warning: eval: invalid operator: `1 = 1'
+@error{}m4:stdin:9: warning: eval: invalid operator: '1 = 1'
 @result{}
 eval(`0 |= 1')
-@error{}m4:stdin:10: warning: eval: invalid operator: `0 |= 1'
+@error{}m4:stdin:10: warning: eval: invalid operator: '0 |= 1'
 @result{}
 eval(`2 || 1 / 0')
 @result{}1
 eval(`0 || 1 / 0')
-@error{}m4:stdin:12: warning: eval: divide by zero: `0 || 1 / 0'
+@error{}m4:stdin:12: warning: eval: divide by zero: '0 || 1 / 0'
 @result{}
 eval(`0 && 1 % 0')
 @result{}0
 eval(`2 && 1 % 0')
-@error{}m4:stdin:14: warning: eval: modulo by zero: `2 && 1 % 0'
+@error{}m4:stdin:14: warning: eval: modulo by zero: '2 && 1 % 0'
 @result{}
 @end example
 
@@ -7754,9 +7754,9 @@ eval(`2 ** 0')
 @result{}1
 eval(`0 ** 0')
 @result{}
-@error{}m4:stdin:5: warning: eval: divide by zero: `0 ** 0'
+@error{}m4:stdin:5: warning: eval: divide by zero: '0 ** 0'
 eval(`4 ** -2')
-@error{}m4:stdin:6: warning: eval: negative exponent: `4 ** -2'
+@error{}m4:stdin:6: warning: eval: negative exponent: '4 ** -2'
 @result{}
 eval(`2 || 4 ** -2')
 @result{}1
@@ -7819,7 +7819,7 @@ square(square(`5')` + 1')
 define(`foo', `666')
 @result{}
 eval(`foo / 6')
-@error{}m4:stdin:11: warning: eval: bad expression: `foo / 6'
+@error{}m4:stdin:11: warning: eval: bad expression: 'foo / 6'
 @result{}
 eval(foo / 6)
 @result{}111
@@ -8780,7 +8780,7 @@ twoline
 @result{}1
 @result{}2
 syncoutput(`blah')
-@error{}m4:stdin:18: warning: syncoutput: unknown directive `blah'
+@error{}m4:stdin:18: warning: syncoutput: unknown directive 'blah'
 @result{}
 @end example
 
@@ -9522,7 +9522,7 @@ forloop(`', `1', `2', ` odd iterator name')
 forloop(`i', `5 + 5', `0xc', ` 0x`'eval(i, `16')')
 @result{} 0xa 0xb 0xc
 forloop(`i', `a', `b', `non-numeric bounds')
-@error{}m4:stdin:6: warning: eval: bad input: `(a) <= (b)'
+@error{}m4:stdin:6: warning: eval: bad input: '(a) <= (b)'
 @result{}
 @end example
 
diff --git a/tests/builtins.at b/tests/builtins.at
index aad46364..1147972a 100644
--- a/tests/builtins.at
+++ b/tests/builtins.at
@@ -218,14 +218,14 @@ AT_CHECK_M4([define.m4], 0,
 [[new value.
 hello, world.
 base value.
-]], [[m4:define.m4:1: warning: undefine: undefined macro `macro'
+]], [[m4:define.m4:1: warning: undefine: undefined macro 'macro'
 ]])
 
 AT_CHECK_M4([--traditional define.m4], 0,
 [[new value.
 hello, world.
 base value.
-]], [[m4:define.m4:1: warning: undefine: undefined macro `macro'
+]], [[m4:define.m4:1: warning: undefine: undefined macro 'macro'
 ]])
 
 dnl check regression present 2008-02-22 to 2008-04-30.
@@ -612,8 +612,8 @@ very late
 ]])
 
 AT_DATA([[experr]],
-[[m4:include.m4:2: include: cannot open `NOFILE': No such file or directory
-m4:include.m4:6: include: cannot open `NOFILE': No such file or directory
+[[m4:include.m4:2: include: cannot open 'NOFILE': No such file or directory
+m4:include.m4:6: include: cannot open 'NOFILE': No such file or directory
 ]])
 
 AT_CHECK_M4([include.m4], 1, expout, experr)
@@ -728,7 +728,7 @@ AT_DATA([[in]],
 [[mkdtemp(`no_such_dir/m4-fooXXXXXX')
 ]])
 AT_CHECK_M4([in], [0], [[
-]], [[m4:in:1: warning: mkdtemp: cannot create directory from template `no_such_dir/m4-fooXXXXXX': No such file or directory
+]], [[m4:in:1: warning: mkdtemp: cannot create directory from template 'no_such_dir/m4-fooXXXXXX': No such file or directory
 ]])
 
 dnl Check that umask has an effect.  drws--S--T is okay.
@@ -757,7 +757,7 @@ AT_DATA([[in]],
 [[mkstemp(`no_such_dir/m4-fooXXXXXX')
 ]])
 AT_CHECK_M4([in], [0], [[
-]], [[m4:in:1: warning: mkstemp: cannot create file from template `no_such_dir/m4-fooXXXXXX': No such file or directory
+]], [[m4:in:1: warning: mkstemp: cannot create file from template 'no_such_dir/m4-fooXXXXXX': No such file or directory
 ]])
 
 dnl Check that extra X are appended, but not trailing NUL
diff --git a/tests/freeze.at b/tests/freeze.at
index b75d5209..4ac25d73 100644
--- a/tests/freeze.at
+++ b/tests/freeze.at
@@ -61,7 +61,7 @@ AT_SETUP([freezing failure])
 AT_KEYWORDS([frozen])
 
 AT_CHECK_M4([-F /none/such], [1], [],
-[[m4: cannot open `/none/such': No such file or directory
+[[m4: cannot open '/none/such': No such file or directory
 ]])
 
 if test -w /dev/full && test -c /dev/full ; then
@@ -170,7 +170,7 @@ define 1
 my_define(bar, 4) 3
 bar${1}
 ]],
-[[m4:input.m4:5: warning: popdef: undefined macro `my_define'
+[[m4:input.m4:5: warning: popdef: undefined macro 'my_define'
 ]])
 
 dnl Test rejection of v2 features in a v1 frozen file
@@ -414,7 +414,7 @@ AT_CHECK([cat out1 stdout], [0], [expout])
 dnl Check that unexpected embedded NULs are recognized.
 printf '# bogus frozen file\nV2\nR4\ngnu\0\n' > bogus.m4f
 AT_CHECK_M4([-R bogus.m4f], [1], [],
-[[m4:bogus.m4f:4: bad syntax-spec `gnu\0'
+[[m4:bogus.m4f:4: bad syntax-spec 'gnu\0'
 ]])
 
 dnl Reject escape sequences that expand to unexpected NUL
@@ -426,7 +426,7 @@ len
 len\0
 ]])
 AT_CHECK_M4([-R bogus.m4f], [1], [],
-[[m4:bogus.m4f:5: ill-formed frozen file, invalid builtin `len\0' encountered
+[[m4:bogus.m4f:5: ill-formed frozen file, invalid builtin 'len\0' encountered
 ]])
 
 AT_CLEANUP
@@ -528,10 +528,10 @@ AT_CHECK_M4([-R frozen.m4f input.m4], 0,
 
 a
 ]],
-[[m4:input.m4:4: warning: defn: a: builtin `b' requested by frozen file not found
-m4:input.m4:6: warning: a: builtin `b' requested by frozen file not found
-m4:input.m4:8: warning: a: builtin `b' requested by frozen file not found
-m4:input.m4:10: warning: builtin: undefined builtin `b'
+[[m4:input.m4:4: warning: defn: a: builtin 'b' requested by frozen file not found
+m4:input.m4:6: warning: a: builtin 'b' requested by frozen file not found
+m4:input.m4:8: warning: a: builtin 'b' requested by frozen file not found
+m4:input.m4:10: warning: builtin: undefined builtin 'b'
 a:	<<b>>
 c:	`'
 ]], [], [ ])
diff --git a/tests/macros.at b/tests/macros.at
index 31b44926..312a606e 100644
--- a/tests/macros.at
+++ b/tests/macros.at
@@ -239,9 +239,9 @@ hej:	`def 4.'
 hej:	`def 3.'
 hej:	`def 2.'
 hej:	`def 1.'
-m4:pushpop.m4:18: warning: dumpdef: undefined macro `hej'
-m4:pushpop.m4:20: warning: dumpdef: undefined macro `mac2'
-m4:pushpop.m4:21: warning: popdef: undefined macro `mac2'
+m4:pushpop.m4:18: warning: dumpdef: undefined macro 'hej'
+m4:pushpop.m4:20: warning: dumpdef: undefined macro 'mac2'
+m4:pushpop.m4:21: warning: popdef: undefined macro 'mac2'
 ]])
 
 AT_CLEANUP
diff --git a/tests/modules.at b/tests/modules.at
index 3b082464..953f06d1 100644
--- a/tests/modules.at
+++ b/tests/modules.at
@@ -133,7 +133,7 @@ Dumpdef: .
 [[Test module loaded.
 test:	<test>
 Test module unloaded.
-m4:input.m4:6: warning: dumpdef: undefined macro `test'
+m4:input.m4:6: warning: dumpdef: undefined macro 'test'
 ]])
 
 AT_CLEANUP
diff --git a/tests/null.err b/tests/null.err
index 2b0b3cf2..d10916d4 100644
--- a/tests/null.err
+++ b/tests/null.err
diff --git a/tests/options.at b/tests/options.at
index 80e70d7d..4771cdae 100644
--- a/tests/options.at
+++ b/tests/options.at
@@ -77,7 +77,7 @@ AT_CHECK_M4([--arglength=10], [0], [],
 
 AT_CHECK_M4([--arglength=x], [1], [],
 [[m4: warning: `--arglength' is deprecated, use `--debuglen' instead
-m4: invalid --arglength argument `x'
+m4: invalid --arglength argument 'x'
 ]])
 
 dnl --word-regexp from 1.4.x is no longer supported.  Can't test for its
@@ -99,7 +99,7 @@ dnl Check that all files are processed even after missing file
 AT_DATA([in], [[hello world
 ]])
 AT_CHECK_M4([oops in], [1], [[hello world
-]], [[m4: cannot open `oops': No such file or directory
+]], [[m4: cannot open 'oops': No such file or directory
 ]])
 
 dnl Check that '-' means stdin, even if ./- exists.
@@ -294,7 +294,7 @@ AT_CHECK([test -f trace3], [1])
 dnl check that trace file failure causes an error, but allows processing
 AT_CHECK_M4([--debugfile=no_such_dir/trace -tfoo -Dfoo=bar in], [1],
 [[bar
-]], [[m4: cannot set debug file `no_such_dir/trace': No such file or directory
+]], [[m4: cannot set debug file 'no_such_dir/trace': No such file or directory
 m4trace: -1- foo -> `bar'
 ]])
 
@@ -345,15 +345,15 @@ echo(`long string')
 ]])
 
 AT_CHECK_M4([--debuglen=-1 in], [1], [],
-[[m4: invalid --debuglen argument `-1'
+[[m4: invalid --debuglen argument '-1'
 ]])
 
 AT_CHECK_M4([--debuglen oops in], [1], [],
-[[m4: invalid --debuglen argument `oops'
+[[m4: invalid --debuglen argument 'oops'
 ]])
 
 AT_CHECK_M4([-l 10oops in], [1], [],
-[[m4: invalid suffix in -l argument `10oops'
+[[m4: invalid suffix in -l argument '10oops'
 ]])
 
 dnl MiB is the suffix to implict 1, resulting in 1048576
@@ -363,10 +363,10 @@ AT_CHECK_M4([-lMiB in], [0], [[long string
 
 dnl this assumes size_t is no bigger than 64 bits
 AT_CHECK_M4([-l 123456789012345678901234567890 in], [1], [],
-[[m4: -l argument `123456789012345678901234567890' too large
+[[m4: -l argument '123456789012345678901234567890' too large
 ]])
 AT_CHECK_M4([--debugl 123456789012345678901234567890 in], [1], [],
-[[m4: --debuglen argument `123456789012345678901234567890' too large
+[[m4: --debuglen argument '123456789012345678901234567890' too large
 ]])
 
 dnl per POSIX guidelines, this is a decimal number 10, not octal 8
@@ -431,11 +431,11 @@ m4debug: module gnu: opening file
 m4debug: module gnu: opened
 m4debug: module gnu: builtins loaded
 m4debug: module gnu: macros loaded
-m4debug: path search for `in' found `in'
-m4debug: input read from `in'
+m4debug: path search for 'in' found 'in'
+m4debug: input read from 'in'
 m4trace:in:1: -1- id 1: include ... = <include>{m4}
-m4debug:in:1: path search for `nested' found `nested'
-m4debug:in:1: input read from `nested'
+m4debug:in:1: path search for 'nested' found 'nested'
+m4debug:in:1: input read from 'nested'
 m4trace:in:1: -1- id 1: include(`nested') -> <file: nested>
 m4trace:nested:1: -1- id 2: m4wrap ... = <m4wrap>{m4}
 m4trace:nested:1: -1- id 2: m4wrap(`divnum
@@ -626,15 +626,15 @@ echo(echo(echo(echo(echo(echo(echo(echo(echo(`nested string')))))))))
 ]])
 
 AT_CHECK_M4([--nesting-limit=-1 in], [1], [],
-[[m4: invalid --nesting-limit argument `-1'
+[[m4: invalid --nesting-limit argument '-1'
 ]])
 
 AT_CHECK_M4([--nesting-limit oops in], [1], [],
-[[m4: invalid --nesting-limit argument `oops'
+[[m4: invalid --nesting-limit argument 'oops'
 ]])
 
 AT_CHECK_M4([-L 10oops in], [1], [],
-[[m4: invalid suffix in -L argument `10oops'
+[[m4: invalid suffix in -L argument '10oops'
 ]])
 
 dnl MiB is the suffix to implict 1, resulting in 1048576
@@ -644,10 +644,10 @@ nested string
 
 dnl this assumes size_t is no bigger than 64 bits
 AT_CHECK_M4([-L 123456789012345678901234567890 in], [1], [],
-[[m4: -L argument `123456789012345678901234567890' too large
+[[m4: -L argument '123456789012345678901234567890' too large
 ]])
 AT_CHECK_M4([--nest 123456789012345678901234567890 in], [1], [],
-[[m4: --nesting-limit argument `123456789012345678901234567890' too large
+[[m4: --nesting-limit argument '123456789012345678901234567890' too large
 ]])
 
 AT_CHECK_M4([-L 5 in], [1], [[nested string
@@ -705,7 +705,7 @@ AT_CHECK_M4([-I post -B pre in], [1],
 [[in pre/foo
 in ./bar
 in post/blah
-]], [[m4:in:3: include: cannot open `bad': No such file or directory
+]], [[m4:in:3: include: cannot open 'bad': No such file or directory
 ]])
 
 AT_CLEANUP
@@ -723,7 +723,7 @@ AT_DATA([[in]], [[regexp(`(', `(')
 ]])
 
 AT_CHECK_M4([--regexp-syntax=unknown in], [1], [],
-[[m4: bad syntax-spec: `unknown'
+[[m4: bad syntax-spec: 'unknown'
 ]])
 
 AT_CHECK_M4([--regexp-syntax= in], [0], [[0
@@ -821,7 +821,7 @@ hi
 dnl test parse error
 AT_CHECK_M4([--syncoutput=huh in], [0],
 [[hi
-]], [[m4: warning: --syncoutput: unknown directive `huh'
+]], [[m4: warning: --syncoutput: unknown directive 'huh'
 ]])
 
 AT_CLEANUP
diff --git a/tests/others.at b/tests/others.at
index 32589570..b095cc66 100644
--- a/tests/others.at
+++ b/tests/others.at
@@ -145,14 +145,14 @@ AT_DATA([in3.m4],
 AT_CHECK_M4([in1.m4/], [1], [], [stderr])
 dnl mingw fails with EINVAL rather than the expected ENOTDIR
 AT_CHECK([$SED 's/Invalid argument/Not a directory/' stderr], [0],
-[[m4: cannot open `in1.m4/': Not a directory
+[[m4: cannot open 'in1.m4/': Not a directory
 ]])
 
 AT_CHECK_M4([in1.m4], [1], [[
 ]], [stderr])
 dnl mingw fails with EINVAL rather than the expected ENOTDIR
 AT_CHECK([$SED 's/Invalid argument/Not a directory/' stderr], [0],
-[[m4:in1.m4:1: include: cannot open `in2.m4/': Not a directory
+[[m4:in1.m4:1: include: cannot open 'in2.m4/': Not a directory
 ]])
 
 AT_CHECK_M4([in2.m4], [0], [[
@@ -163,7 +163,7 @@ AT_CHECK_M4([in3.m4], [1], [[
 ]], [stderr])
 dnl mingw fails with EACCES rather than the expected EISDIR
 AT_CHECK([$SED 's/Permission denied/Is a directory/' stderr], [0],
-[[m4:in3.m4:1: include: cannot open `.': Is a directory
+[[m4:in3.m4:1: include: cannot open '.': Is a directory
 ]])
 
 AT_CLEANUP
@@ -437,7 +437,7 @@ AT_CHECK_M4(["$abs_srcdir/null.m4"], [1],
 [[# This file tests m4 behavior on NUL bytes.
 ]], [stderr])
 AT_CHECK([sed "s|$abs_srcdir/||" stderr], [0],
-[[m4:null.m4:5: warning: m4exit: non-numeric argument `2\0002'
+[[m4:null.m4:5: warning: m4exit: non-numeric argument '2\0002'
 ]])
 
 AT_CLEANUP
@@ -630,13 +630,13 @@ AT_CHECK_M4([in.m4], [0], [ignore], [ignore], [-])
 
 dnl error when stdin must be read
 AT_CHECK_M4([], [1], [],
-[[m4:stdin:1: error reading `stdin'
+[[m4:stdin:1: error reading 'stdin'
 m4: error closing file: Bad file descriptor
 ]], [-])
 
 dnl error when stdin must be read
 AT_CHECK_M4([-], [1], [],
-[[m4:stdin:1: error reading `stdin'
+[[m4:stdin:1: error reading 'stdin'
 m4: error closing file: Bad file descriptor
 ]], [-])
 
@@ -644,8 +644,8 @@ dnl error once per command-line attempt to read stdin
 AT_DATA([in.m4], [[hello world
 ]])
 AT_CHECK_M4([- in.m4 -], [1], [[hello world
-]], [[m4:stdin:1: error reading `stdin'
-m4:stdin:1: error reading `stdin'
+]], [[m4:stdin:1: error reading 'stdin'
+m4:stdin:1: error reading 'stdin'
 m4: error closing file: Bad file descriptor
 ]], [-])
 
@@ -670,7 +670,7 @@ AT_DATA([in2.m4], [[divert(`-1')undivert
 divert`'world
 ]])
 AT_CHECK_M4([in.m4 - in2.m4], [1], [[hello world
-]], [[m4:stdin:1: error reading `stdin'
+]], [[m4:stdin:1: error reading 'stdin'
 m4: error closing file: Bad file descriptor
 ]], [-])