Fix #283: Make warnings(false) actually suppress compiler warnings

Previously, calling warnings(false) didn't add any flags, so the compiler still showed warnings. Now it actively adds -w (GCC/Clang) or -W0 (MSVC) to properly disable them. Changes: - Added warnings_suppression_flags() method to ToolFamily - Modified warning logic to handle warnings(false) case explicitly - Added tests for GNU and MSVC warning suppression

Author: naoNao89

src/lib.rs

@@ -1997,9 +1997,21 @@ impl Build {
  // CFLAGS/CXXFLAGS, since those variables presumably already contain
  // the desired set of warnings flags.
  let envflags = self.envflags(if self.cpp { "CXXFLAGS" } else { "CFLAGS" })?;
- if self.warnings.unwrap_or(envflags.is_none()) {
- let wflags = cmd.family.warnings_flags().into();
- cmd.push_cc_arg(wflags);
+ match self.warnings {
+ Some(true) => {
+ let wflags = cmd.family.warnings_flags().into();
+ cmd.push_cc_arg(wflags);
+ }
+ Some(false) => {
+ let wflags = cmd.family.warnings_suppression_flags().into();
+ cmd.push_cc_arg(wflags);
+ }
+ None => {
+ if envflags.is_none() {
+ let wflags = cmd.family.warnings_flags().into();
+ cmd.push_cc_arg(wflags);
+ }
+ }
  }
  if self.extra_warnings.unwrap_or(envflags.is_none()) {
  if let Some(wflags) = cmd.family.extra_warnings_flags() {

src/tool.rs

@@ -566,6 +566,13 @@ impl ToolFamily {
  }
  }
 
+ pub(crate) fn warnings_suppression_flags(&self) -> &'static str {
+ match *self {
+ ToolFamily::Msvc { .. } => "-W0",
+ ToolFamily::Gnu | ToolFamily::Clang { .. } => "-w",
+ }
+ }
+
  /// What the flags to enable extra warnings
  pub(crate) fn extra_warnings_flags(&self) -> Option<&'static str> {
  match *self {

tests/test.rs

@@ -173,6 +173,14 @@ fn gnu_warnings() {
  test.cmd(0).must_have("-Wall").must_have("-Wextra");
 }
 
+#[test]
+fn gnu_warnings_disabled() {
+ let test = Test::gnu();
+ test.gcc().warnings(false).file("foo.c").compile("foo");
+
+ test.cmd(0).must_have("-w").must_not_have("-Wall");
+}
+
 #[test]
 fn gnu_extra_warnings0() {
  reset_env();
@@ -200,7 +208,10 @@ fn gnu_extra_warnings1() {
  .file("foo.c")
  .compile("foo");
 
- test.cmd(0).must_not_have("-Wall").must_have("-Wextra");
+ test.cmd(0)
+ .must_have("-w")
+ .must_not_have("-Wall")
+ .must_have("-Wextra");
 }
 
 #[test]
@@ -533,6 +544,14 @@ fn msvc_std_c() {
  test.cmd(0).must_have("-std:c11");
 }
 
+#[test]
+fn msvc_warnings_disabled() {
+ let test = Test::msvc();
+ test.gcc().warnings(false).file("foo.c").compile("foo");
+
+ test.cmd(0).must_have("-W0").must_not_have("-W4");
+}
+
 // Disable this test with the parallel feature because the execution
 // order is not deterministic.
 #[cfg(not(feature = "parallel"))]