Add note about cargo in README, make debug symbols included by default for manual compilation

Makefile

@@ -32,7 +32,7 @@ RUN_TESTS_CMD := REPORT_EXIT_STATUS=1 TEST_PHP_SRCDIR=$(PROJECT_ROOT) USE_TRACKE
 
 C_FILES = $(shell find components components-rs ext src/dogstatsd zend_abstract_interface -name '*.c' -o -name '*.h' | awk '{ printf "$(BUILD_DIR)/%s\n", $$1 }' )
 TEST_FILES = $(shell find tests/ext -name '*.php*' -o -name '*.inc' -o -name '*.json' -o -name 'CONFLICTS' | awk '{ printf "$(BUILD_DIR)/%s\n", $$1 }' )
-RUST_FILES = $(BUILD_DIR)/Cargo.toml $(shell find components-rs -name '*.c' -o -name '*.rs' -o -name 'Cargo.toml' | awk '{ printf "$(BUILD_DIR)/%s\n", $$1 }' ) $(shell find libdatadog/{ddcommon,ddcommon-ffi,ddtelemetry,ddtelemetry-ffi,ipc,sidecar,sidecar-ffi,spawn_worker,tools/{cc_utils,sidecar_mockgen},Cargo.toml} -type f \( -path "*/src*" -o -path "*Cargo.toml" -o -path "*/build.rs" \) -not -path "*/ipc/build.rs" -not -path "*/sidecar-ffi/build.rs")
+RUST_FILES = $(BUILD_DIR)/Cargo.toml $(shell find components-rs -name '*.c' -o -name '*.rs' -o -name 'Cargo.toml' | awk '{ printf "$(BUILD_DIR)/%s\n", $$1 }' ) $(shell find libdatadog/{ddcommon,ddcommon-ffi,ddtelemetry,ddtelemetry-ffi,ipc,sidecar,sidecar-ffi,spawn_worker,tools/{cc_utils,sidecar_mockgen},Cargo.toml} -type f \( -path "*/src*" -o -path "*/examples*" -o -path "*Cargo.toml" -o -path "*/build.rs" -o -path "*/tests/dataservice.rs" -o -path "*/tests/service_functional.rs" \) -not -path "*/ipc/build.rs" -not -path "*/sidecar-ffi/build.rs")
 TEST_OPCACHE_FILES = $(shell find tests/opcache -name '*.php*' -o -name '.gitkeep' | awk '{ printf "$(BUILD_DIR)/%s\n", $$1 }' )
 TEST_STUB_FILES = $(shell find tests/ext -type d -name 'stubs' -exec find '{}' -type f \; | awk '{ printf "$(BUILD_DIR)/%s\n", $$1 }' )
 INIT_HOOK_TEST_FILES = $(shell find tests/C2PHP -name '*.phpt' -o -name '*.inc' | awk '{ printf "$(BUILD_DIR)/%s\n", $$1 }' )
@@ -85,7 +85,7 @@ $(BUILD_DIR)/configure: $(M4_FILES) $(BUILD_DIR)/ddtrace.sym
 	$(Q) (cd $(BUILD_DIR); phpize && sed -i 's/\/FAILED/\/\\bFAILED/' $(BUILD_DIR)/run-tests.php) # Fix PHP 5.4 exit code bug when running selected tests (FAILED vs XFAILED)
 
 $(BUILD_DIR)/Makefile: $(BUILD_DIR)/configure
-	$(Q) (cd $(BUILD_DIR); ./configure --enable-ddtrace-rust-symbols=$(if $(RUST_DEBUG_SYMBOLS),yes,no))
+	$(Q) (cd $(BUILD_DIR); ./configure --enable-ddtrace-rust-debug=$(if $(RUST_DEBUG_SYMBOLS),yes,no) --enable-ddtrace-rust-symbols=$(if $(RUST_DEBUG_SYMBOLS),yes,no))
 
 $(SO_FILE): $(C_FILES) $(RUST_FILES) $(BUILD_DIR)/Makefile
 	$(Q) $(MAKE) -C $(BUILD_DIR) -j CFLAGS="$(CFLAGS)$(if $(ASAN), -fsanitize=address)" LDFLAGS="$(LDFLAGS)$(if $(ASAN), -fsanitize=address)"

README.md

@@ -20,6 +20,10 @@ Datadog’s PHP Tracing Library supports many of the most common PHP versions, P
 
 Visit the [PHP tracer documentation](https://docs.datadoghq.com/tracing/languages/php/) for complete installation instructions.
 
+#### Installation from PECL (datadog_trace) or from source
+
+Compilation of the tracer and the profiler requires cargo to be installed. Ensure that cargo is minimum version 1.64.0, otherwise follow the [official instructions for installing cargo](https://doc.rust-lang.org/cargo/getting-started/installation.html).
+
 ### Advanced configuration
 
 For more information about configuring and instrumenting **ddtrace**, view the [configuration documentation](https://docs.datadoghq.com/tracing/setup/php/#configuration).

config.m4

@@ -7,8 +7,11 @@ PHP_ARG_WITH(ddtrace-sanitize, whether to enable AddressSanitizer for ddtrace,
 PHP_ARG_WITH(ddtrace-cargo, where cargo is located for rust code compilation,
   [  --with-ddtrace-cargo Location to cargo binary for rust compilation], cargo, not found)
 
-PHP_ARG_ENABLE(ddtrace-rust-symbols, whether to compile rust in debug mode,
-  [  --enable-ddtrace-rust-symbols Build with debug symbols included in the rust archive], [[$(test "${CFLAGS#*-g}" != "${CFLAGS}" && test "${CFLAGS#*-g0}" == "${CFLAGS}" && echo yes || echo no)]], [no])
+PHP_ARG_ENABLE(ddtrace-rust-debug, whether to compile rust in debug mode,
+  [  --enable-ddtrace-rust-debug Build rust code in debug mode (significantly slower)], [[$(test "${CFLAGS#*-g}" != "${CFLAGS}" && test "${CFLAGS#*-g0}" == "${CFLAGS}" && echo yes || echo no)]], [no])
+
+PHP_ARG_ENABLE(ddtrace-rust-symbols, whether to keep rust debug symbols,
+  [  --disable-ddtrace-rust-symbols Strip debug symbols from the rust archive (significantly reduces artifact size)], [yes], [yes])
 
 if test "$PHP_DDTRACE" != "no"; then
   AC_CHECK_SIZEOF([long])
@@ -274,7 +277,7 @@ if test "$PHP_DDTRACE" != "no"; then
 
   cat <<EOT >> Makefile.fragments
 \$(builddir)/target/$ddtrace_cargo_profile/libddtrace_php.a: $( (find "$ext_srcdir/components-rs" -name "*.c" -o -name "*.rs" -o -name "Cargo.toml"; find "$ext_srcdir/../../libdatadog" -name "*.rs" -exclude "target"; find "$ext_srcdir/libdatadog" -name "*.rs" -exclude "target"; echo "$all_object_files" ) | xargs )
-	(cd "$ext_srcdir/components-rs"; $ddtrace_mock_sources CARGO_TARGET_DIR=\$(builddir)/target/ \$(DDTRACE_CARGO) build $(test "$ddtrace_cargo_profile" == debug || echo --profile tracer-release) && test "$ddtrace_cargo_profile" == debug || strip -d \$(builddir)/target/$ddtrace_cargo_profile/libddtrace_php.a)
+	(cd "$ext_srcdir/components-rs"; $ddtrace_mock_sources CARGO_TARGET_DIR=\$(builddir)/target/ \$(DDTRACE_CARGO) build $(test "$ddtrace_cargo_profile" == debug || echo --profile tracer-release) && test "$PHP_DDTRACE_RUST_SYMBOLS" == no || strip -d \$(builddir)/target/$ddtrace_cargo_profile/libddtrace_php.a)
 EOT
 
   if test "$ext_shared" = "shared" || test "$ext_shared" = "yes"; then