> When writing to an old-style "[section.subsection]" header, the
> config file parser always folds the subsection to lower case
> (get_base_var() lowercases unconditionally), while the key given on
> the command line keeps whatever case the caller typed
> (do_parse_config_key() deliberately leaves the subsection segment
> untouched). matches() compared these two forms with a plain strcmp(),
> so a caller passing an upper-cased subsection (e.g. 'git config
> section.Subsection.key value2' against a file containing
> '[section.subsection]') never matched the existing key and a
> duplicate line was appended instead of replacing the value. This was
> a known, documented limitation (see the now-removed BUGS section of
> git-config.adoc).
>
> Track whether the currently active section was parsed case-
> insensitively (old-style) or case-sensitively (new-style, quoted) in
> struct config_store_data, and have matches() use that information to
> compare the subsection segment of the key accordingly, instead of an
> unconditional case-sensitive strcmp().
>
> Signed-off-by: RISHAV DEWAN <rishavdewan10@gmail.com>
> ---
>  Documentation/git-config.adoc | 21 ---------------------
>  config.c                      | 18 +++++++++++++++++-
>  t/t1300-config.sh             |  2 --
>  3 files changed, 17 insertions(+), 24 deletions(-)
>
> diff --git a/Documentation/git-config.adoc b/Documentation/git-config.adoc
> index 57af010ade..11dfd802b4 100644
> --- a/Documentation/git-config.adoc
> +++ b/Documentation/git-config.adoc
> @@ -634,27 +634,6 @@ http.sslverify false
>  
>  include::config.adoc[]
>  
> -BUGS
> -----
> -When using the deprecated `[section.subsection]` syntax, changing a value
> -will result in adding a multi-line key instead of a change, if the subsection
> -is given with at least one uppercase character. For example when the config
> -looks like
> -
> ---------
> -  [section.subsection]
> -    key = value1
> ---------
> -
> -and running `git config section.Subsection.key value2` will result in
> -
> ---------
> -  [section.subsection]
> -    key = value1
> -    key = value2
> ---------
> -
> -
>  GIT
>  ---
>  Part of the linkgit:git[1] suite
> diff --git a/config.c b/config.c
> index 6a0de86e3a..7f086fcd75 100644
> --- a/config.c
> +++ b/config.c
> @@ -2594,6 +2594,7 @@ struct config_store_data {
>  	} *parsed;
>  	unsigned int parsed_nr, parsed_alloc, *seen, seen_nr, seen_alloc;
>  	unsigned int key_seen:1, section_seen:1, is_keys_section:1;
> +	unsigned int subsection_case_sensitive:1;
>  };
>  #define CONFIG_STORE_INIT { 0 }
>  
> @@ -2613,7 +2614,21 @@ static void config_store_data_clear(struct config_store_data *store)
>  static int matches(const char *key, const char *value,
>  		   const struct config_store_data *store)
>  {
> -	if (strcmp(key, store->key))
> +	/*
> +	 * The subsection part of "key" (key[0..store->baselen)) was parsed
> +	 * out of the config file using the case sensitivity of whichever
> +	 * section header it came from (see store_aux_event()): old-style
> +	 * "[section.subsection]" headers are folded to lower case while
> +	 * parsing, so they must be compared case-insensitively against
> +	 * store->key, which preserves whatever case the caller passed on
> +	 * the command line. New-style "[section "Subsection"]" headers keep
> +	 * their case, so they need an exact, case-sensitive comparison.
> +	 */
> +	int (*cmpfn)(const char *, const char *, size_t) =
> +		store->subsection_case_sensitive ? strncasecmp : strncmp;
> +
> +	if (cmpfn(key, store->key, store->baselen) ||
> +	    strcmp(key + store->baselen, store->key + store->baselen))
>  		return 0; /* not ours */
>  	if (store->fixed_value && value)
>  		return !strcmp(store->fixed_value, value);
> @@ -2654,6 +2669,7 @@ static int store_aux_event(enum config_event_t type, size_t begin, size_t end,
>  			!cmpfn(cs->var.buf, store->key, store->baselen);
>  		if (store->is_keys_section) {
>  			store->section_seen = 1;
> +			store->subsection_case_sensitive = cs->subsection_case_sensitive;
>  			ALLOC_GROW(store->seen, store->seen_nr + 1,
>  				   store->seen_alloc);
>  			store->seen[store->seen_nr] = store->parsed_nr;
> diff --git a/t/t1300-config.sh b/t/t1300-config.sh
> index 87ca11a127..eaa3b83990 100755
> --- a/t/t1300-config.sh
> +++ b/t/t1300-config.sh
> @@ -1499,7 +1499,6 @@ test_expect_success 'old-fashioned settings are case insensitive' '
>  	EOF
>  	q_to_tab >testConfig_expect <<-EOF &&
>  	[V.A]
> -	r = value1
>  	Qr = value2
>  	EOF
>  	git config -f testConfig_actual "V.A.r" value2 &&
> @@ -1511,7 +1510,6 @@ test_expect_success 'old-fashioned settings are case insensitive' '
>  	EOF
>  	q_to_tab >testConfig_expect <<-EOF &&
>  	[V.A]
> -	r = value1
>  	Qr = value2
>  	EOF
>  	git config -f testConfig_actual "v.A.r" value2 &&