builtin,os: enable no warnings for gg programs like v -gc boehm_leak -cg -keepc run examples/gg/minimal.v (part 1 - before the gg loop) (#24749)

vlib/builtin/string.v

@@ -455,6 +455,9 @@ pub fn (s string) replace_each(vals []string) string {
 	// of the new string to do just one allocation.
 	mut new_len := s.len
 	mut idxs := []RepIndex{cap: 6}
+	defer {
+		unsafe { idxs.free() }
+	}
 	mut idx := 0
 	s_ := s.clone()
 	for rep_i := 0; rep_i < vals.len; rep_i += 2 {
@@ -845,6 +848,8 @@ fn (s string) plus_two(a string, b string) string {
 @[direct_array_access]
 pub fn (s string) split_any(delim string) []string {
 	mut res := []string{}
+	unsafe { res.flags.set(.noslices) }
+	defer { unsafe { res.flags.clear(.noslices) } }
 	mut i := 0
 	// check empty source string
 	if s.len > 0 {
@@ -874,6 +879,8 @@ pub fn (s string) split_any(delim string) []string {
 @[direct_array_access]
 pub fn (s string) rsplit_any(delim string) []string {
 	mut res := []string{}
+	unsafe { res.flags.set(.noslices) }
+	defer { unsafe { res.flags.clear(.noslices) } }
 	mut i := s.len - 1
 	if s.len > 0 {
 		if delim.len <= 0 {
@@ -964,6 +971,8 @@ pub fn (s string) split_n(delim string, n int) []string {
 @[direct_array_access]
 pub fn (s string) split_nth(delim string, nth int) []string {
 	mut res := []string{}
+	unsafe { res.flags.set(.noslices) } // allow freeing of old data during <<
+	defer { unsafe { res.flags.clear(.noslices) } }
 
 	match delim.len {
 		0 {
@@ -1023,6 +1032,8 @@ pub fn (s string) split_nth(delim string, nth int) []string {
 @[direct_array_access]
 pub fn (s string) rsplit_nth(delim string, nth int) []string {
 	mut res := []string{}
+	unsafe { res.flags.set(.noslices) } // allow freeing of old data during <<
+	defer { unsafe { res.flags.clear(.noslices) } }
 
 	match delim.len {
 		0 {
@@ -1082,6 +1093,8 @@ pub fn (s string) split_into_lines() []string {
 	if s.len == 0 {
 		return res
 	}
+	unsafe { res.flags.set(.noslices) } // allow freeing of old data during <<
+	defer { unsafe { res.flags.clear(.noslices) } }
 	cr := `\r`
 	lf := `\n`
 	mut line_start := 0
@@ -1110,6 +1123,8 @@ pub fn (s string) split_into_lines() []string {
 // Repeated, trailing or leading whitespaces will be omitted.
 pub fn (s string) split_by_space() []string {
 	mut res := []string{}
+	unsafe { res.flags.set(.noslices) }
+	defer { unsafe { res.flags.clear(.noslices) } }
 	for word in s.split_any(' \n\t\v\f\r') {
 		if word != '' {
 			res << word
@@ -2466,6 +2481,8 @@ pub fn (s string) repeat(count int) string {
 // Example: assert '  sss   ssss'.fields() == ['sss', 'ssss']
 pub fn (s string) fields() []string {
 	mut res := []string{}
+	unsafe { res.flags.set(.noslices) }
+	defer { unsafe { res.flags.clear(.noslices) } }
 	mut word_start := 0
 	mut word_len := 0
 	mut is_in_word := false

vlib/os/asset/asset.v

@@ -6,11 +6,14 @@ import os
 // of a resource in it. On desktop systems, it returns a path relative to the location of the executable.
 // On Android, it will return just the relative_path segment, allowing you to later use os.read_apk_asset
 // to read from it.
+@[manualfree]
 pub fn get_path(base_folder string, relative_path string) string {
 	$if android {
-		return relative_path
+		return relative_path.clone()
 	} $else {
-		return os.resource_abs_path(os.join_path(base_folder, relative_path))
+		fpath := os.join_path_single(base_folder, relative_path)
+		defer { unsafe { fpath.free() } }
+		return os.resource_abs_path(fpath)
 	}
 }
 
@@ -18,17 +21,24 @@ pub fn get_path(base_folder string, relative_path string) string {
 // On Android, it will use os.read_apk_asset, relying that the asset base folder has been prepared, and
 // prepackaged inside your APK. On desktop systems, it will use the base_folder and relative_path, to
 // locate the file, in a way, that is relative to the executable.
+@[manualfree]
 pub fn read_bytes(base_folder string, relative_path string) ![]u8 {
+	fpath := get_path(base_folder, relative_path)
+	defer { unsafe { fpath.free() } }
+	mut f_read := os.read_bytes
 	$if android {
-		return os.read_apk_asset(get_path(base_folder, relative_path))
-	} $else {
-		return os.read_bytes(get_path(base_folder, relative_path))
+		f_read = os.read_apk_asset
 	}
+	res := f_read(fpath)!
+	return res
 }
 
 // read_text will return the full content of the given asset as a string.
 // See also read_bytes.
+@[manualfree]
 pub fn read_text(base_folder string, relative_path string) !string {
-	res := read_bytes(base_folder, relative_path)!
-	return res.bytestr()
+	bytes := read_bytes(base_folder, relative_path)!
+	defer { unsafe { bytes.free() } }
+	res := bytes.bytestr()
+	return res
 }

vlib/os/font/font.v

@@ -22,11 +22,13 @@ fn debug_font_println(s string) {
 // If the env variable `VUI_FONT` is set this is used instead.
 // NOTE that, in some cases, the function calls out to external OS programs
 // so running this in a hot loop is not advised.
+@[manualfree]
 pub fn default() string {
 	env_font := os.getenv('VUI_FONT')
 	if env_font != '' && os.exists(env_font) {
 		return env_font
 	}
+	unsafe { env_font.free() }
 	$if windows {
 		if os.exists('C:\\Windows\\Fonts\\segoeui.ttf') {
 			debug_font_println('Using font "C:\\Windows\\Fonts\\segoeui.ttf"')
@@ -44,6 +46,7 @@ pub fn default() string {
 				return font
 			}
 		}
+		unsafe { fonts.free() }
 	}
 	$if android {
 		xml_files := ['/system/etc/system_fonts.xml', '/system/etc/fonts.xml',
@@ -54,6 +57,7 @@ pub fn default() string {
 			if os.is_file(xml_file) && os.is_readable(xml_file) {
 				xml := os.read_file(xml_file) or { continue }
 				lines := xml.split('\n')
+				unsafe { xml.free() }
 				mut candidate_font := ''
 				for line in lines {
 					if line.contains('<font') {
@@ -65,12 +69,16 @@ pub fn default() string {
 									debug_font_println('Using font "${candidate_path}"')
 									return candidate_path
 								}
+								unsafe { candidate_path.free() }
 							}
 						}
 					}
 				}
+				unsafe { candidate_font.free() }
 			}
 		}
+		unsafe { font_locations.free() }
+		unsafe { xml_files.free() }
 	}
 	mut fm := os.execute("fc-match --format='%{file}\n' -s")
 	if fm.exit_code == 0 {
@@ -81,59 +89,93 @@ pub fn default() string {
 				return l
 			}
 		}
+		unsafe { lines.free() }
 	} else {
 		panic('fc-match failed to fetch system font')
 	}
+	unsafe { fm.free() }
 	panic('failed to init the font')
 }
 
 // get_path_variant returns the `font_path` file name replaced with the
 // file name of the font's `variant` version if it exists.
+@[manualfree]
 pub fn get_path_variant(font_path string, variant Variant) string {
 	// TODO: find some way to make this shorter and more eye-pleasant
 	// NotoSans, LiberationSans, DejaVuSans, Arial and SFNS should work
 	mut file := os.file_name(font_path)
+	defer { unsafe { file.free() } }
+
 	mut fpath := font_path.replace(file, '')
-	file = file.replace('.ttf', '')
+	defer { unsafe { fpath.free() } }
+
+	mut_replace(file, '.ttf', '')
+
+	flower := file.to_lower()
+	defer { unsafe { flower.free() } }
 
 	match variant {
 		.normal {}
 		.bold {
 			if fpath.ends_with('-Regular') {
-				file = file.replace('-Regular', '-Bold')
+				mut_replace(file, '-Regular', '-Bold')
 			} else if file.starts_with('DejaVuSans') {
-				file += '-Bold'
-			} else if file.to_lower().starts_with('arial') {
-				file += 'bd'
+				mut_plus(file, '-Bold')
+			} else if flower.starts_with('arial') {
+				mut_plus(file, 'bd')
 			} else {
-				file += '-bold'
+				mut_plus(file, '-bold')
 			}
 			$if macos {
 				if os.exists('SFNS-bold') {
-					file = 'SFNS-bold'
+					mut_assign(file, 'SFNS-bold')
 				}
 			}
 		}
 		.italic {
 			if file.ends_with('-Regular') {
-				file = file.replace('-Regular', '-Italic')
+				mut_replace(file, '-Regular', '-Italic')
 			} else if file.starts_with('DejaVuSans') {
-				file += '-Oblique'
-			} else if file.to_lower().starts_with('arial') {
-				file += 'i'
+				mut_plus(file, '-Oblique')
+			} else if flower.starts_with('arial') {
+				mut_plus(file, 'i')
 			} else {
-				file += 'Italic'
+				mut_plus(file, 'Italic')
 			}
 		}
 		.mono {
 			if !file.ends_with('Mono-Regular') && file.ends_with('-Regular') {
-				file = file.replace('-Regular', 'Mono-Regular')
-			} else if file.to_lower().starts_with('arial') {
+				mut_replace(file, '-Regular', 'Mono-Regular')
+			} else if flower.starts_with('arial') {
 				// Arial has no mono variant
 			} else {
-				file += 'Mono'
+				mut_plus(file, 'Mono')
 			}
 		}
 	}
-	return '${fpath}${file}.ttf'
+	res := '${fpath}${file}.ttf'
+	return res
+}
+
+fn mut_replace(s &string, find string, replacement string) {
+	new := (*s).replace(find, replacement)
+	unsafe { s.free() }
+	unsafe {
+		*s = new
+	}
+}
+
+fn mut_plus(s &string, tail string) {
+	new := (*s) + tail
+	unsafe { s.free() }
+	unsafe {
+		*s = new
+	}
+}
+
+fn mut_assign(s &string, value string) {
+	unsafe { s.free() }
+	unsafe {
+		*s = value.clone()
+	}
 }