diff --git a/change_notes/2024-09-18-handle-warning-suppresion-flags b/change_notes/2024-09-18-handle-warning-suppresion-flags
new file mode 100644
index 000000000..12bf30e93
--- /dev/null
+++ b/change_notes/2024-09-18-handle-warning-suppresion-flags
@@ -0,0 +1,2 @@
+- `A1-1-2` - `CompilerWarningLevelNotInCompliance.ql`:
+  - Fixes #689 false negatives where '-Wno-foo' was treated as enabling, rather than disabling warnings.
\ No newline at end of file
diff --git a/cpp/autosar/src/rules/A1-1-2/CompilerWarningLevelNotInCompliance.ql b/cpp/autosar/src/rules/A1-1-2/CompilerWarningLevelNotInCompliance.ql
index 60efab251..55f67a930 100644
--- a/cpp/autosar/src/rules/A1-1-2/CompilerWarningLevelNotInCompliance.ql
+++ b/cpp/autosar/src/rules/A1-1-2/CompilerWarningLevelNotInCompliance.ql
@@ -18,14 +18,61 @@
 import cpp
 import codingstandards.cpp.autosar
 
+predicate hasResponseFileArgument(Compilation c) { c.getAnArgument().matches("@%") }
+
 class CompilationWithNoWarnings extends Compilation {
   CompilationWithNoWarnings() {
     getAnArgument() = "-w" or
-    not getAnArgument().regexpMatch("-W[\\w=-]+")
+    not exists(EnableWarningFlag enableFlag | 
+      this.getAnArgument() = enableFlag and
+      not exists(DisableWarningFlag disableFlag |
+        this.getAnArgument() = disableFlag and
+        enableFlag.getWarningType() = disableFlag.getWarningType()
+      )
+    )
   }
 }
 
-predicate hasResponseFileArgument(Compilation c) { c.getAnArgument().matches("@%") }
+class CompilationArgument extends string {
+  Compilation compilation;
+
+  CompilationArgument() {
+    this = compilation.getAnArgument()
+  }
+}
+
+/**
+ * Compiler flags of type -Wfoo or -Wfoo=bar, which enables the `foo` warning.
+ */
+class EnableWarningFlag extends CompilationArgument {
+  string warningType;
+
+  EnableWarningFlag() {
+    warningType = regexpCapture("^-W([\\w-]+)(=.*)?$", 1)
+    and not this instanceof DisableWarningFlag
+  }
+
+  string getWarningType() {
+    result = warningType
+  }
+}
+
+/**
+ * Compiler flags of type -Wno-foo or -Wfoo=0, which disables the `foo` warning
+ * and overrules -Wfoo.
+ */
+class DisableWarningFlag extends CompilationArgument {
+  string warningType;
+
+  DisableWarningFlag() {
+    warningType = regexpCapture("^-Wno-([\\w-]+)", 1) or
+    warningType = regexpCapture("^-W([\\w-]+)=0", 1)
+  }
+
+  string getWarningType() {
+    result = warningType
+  }
+}
 
 from File f
 where
diff --git a/cpp/autosar/test/rules/A1-1-2.4/CompilerWarningLevelNotInCompliance.expected b/cpp/autosar/test/rules/A1-1-2.4/CompilerWarningLevelNotInCompliance.expected
new file mode 100644
index 000000000..dd7f320be
--- /dev/null
+++ b/cpp/autosar/test/rules/A1-1-2.4/CompilerWarningLevelNotInCompliance.expected
@@ -0,0 +1 @@
+| Wformat=0-Wno-format-security.cpp:0:0:0:0 | Wformat=0-Wno-format-security.cpp | No warning-level options were used in the compilation of 'Wformat=0-Wno-format-security.cpp'. |
diff --git a/cpp/autosar/test/rules/A1-1-2.4/CompilerWarningLevelNotInCompliance.qlref b/cpp/autosar/test/rules/A1-1-2.4/CompilerWarningLevelNotInCompliance.qlref
new file mode 100644
index 000000000..30fb98b63
--- /dev/null
+++ b/cpp/autosar/test/rules/A1-1-2.4/CompilerWarningLevelNotInCompliance.qlref
@@ -0,0 +1 @@
+rules/A1-1-2/CompilerWarningLevelNotInCompliance.ql
\ No newline at end of file
diff --git a/cpp/autosar/test/rules/A1-1-2.4/Wformat=0-Wno-format-security.cpp b/cpp/autosar/test/rules/A1-1-2.4/Wformat=0-Wno-format-security.cpp
new file mode 100644
index 000000000..29523ad24
--- /dev/null
+++ b/cpp/autosar/test/rules/A1-1-2.4/Wformat=0-Wno-format-security.cpp
@@ -0,0 +1,2 @@
+// semmle-extractor-options: --clang -std=c++14 -Wformat=0 -Wno-format-security
+// NON_COMPLIANT
\ No newline at end of file
diff --git a/cpp/autosar/test/rules/A1-1-2.4/options.clang b/cpp/autosar/test/rules/A1-1-2.4/options.clang
new file mode 100644
index 000000000..4544f91ec
--- /dev/null
+++ b/cpp/autosar/test/rules/A1-1-2.4/options.clang
@@ -0,0 +1 @@
+-Wformat=0 -Wno-format-security
\ No newline at end of file
diff --git a/cpp/autosar/test/rules/A1-1-2.4/options.gcc b/cpp/autosar/test/rules/A1-1-2.4/options.gcc
new file mode 100644
index 000000000..4544f91ec
--- /dev/null
+++ b/cpp/autosar/test/rules/A1-1-2.4/options.gcc
@@ -0,0 +1 @@
+-Wformat=0 -Wno-format-security
\ No newline at end of file
diff --git a/cpp/autosar/test/rules/A1-1-2.4/options.qcc b/cpp/autosar/test/rules/A1-1-2.4/options.qcc
new file mode 100644
index 000000000..e28a2c3ac
--- /dev/null
+++ b/cpp/autosar/test/rules/A1-1-2.4/options.qcc
@@ -0,0 +1 @@
+-Wno-format -Wno-format-security
\ No newline at end of file
diff --git a/cpp/autosar/test/rules/A1-1-2.5/CompilerWarningLevelNotInCompliance.expected b/cpp/autosar/test/rules/A1-1-2.5/CompilerWarningLevelNotInCompliance.expected
new file mode 100644
index 000000000..df69d21d5
--- /dev/null
+++ b/cpp/autosar/test/rules/A1-1-2.5/CompilerWarningLevelNotInCompliance.expected
@@ -0,0 +1 @@
+| Wall-Wno-format.cpp:0:0:0:0 | Wall-Wno-format.cpp | No warning-level options were used in the compilation of 'Wall-Wno-format.cpp'. |
\ No newline at end of file
diff --git a/cpp/autosar/test/rules/A1-1-2.5/CompilerWarningLevelNotInCompliance.expected.clang b/cpp/autosar/test/rules/A1-1-2.5/CompilerWarningLevelNotInCompliance.expected.clang
new file mode 100644
index 000000000..e69de29bb
diff --git a/cpp/autosar/test/rules/A1-1-2.5/CompilerWarningLevelNotInCompliance.expected.gcc b/cpp/autosar/test/rules/A1-1-2.5/CompilerWarningLevelNotInCompliance.expected.gcc
new file mode 100644
index 000000000..e69de29bb
diff --git a/cpp/autosar/test/rules/A1-1-2.5/CompilerWarningLevelNotInCompliance.expected.qcc b/cpp/autosar/test/rules/A1-1-2.5/CompilerWarningLevelNotInCompliance.expected.qcc
new file mode 100644
index 000000000..c6354c247
--- /dev/null
+++ b/cpp/autosar/test/rules/A1-1-2.5/CompilerWarningLevelNotInCompliance.expected.qcc
@@ -0,0 +1 @@
+| Wall-Wno-format.cpp:0:0:0:0 | Wall-Wno-format.cpp | No warning-level options were used in the compilation of 'Wall-Wno-format.cpp'. |
diff --git a/cpp/autosar/test/rules/A1-1-2.5/CompilerWarningLevelNotInCompliance.qlref b/cpp/autosar/test/rules/A1-1-2.5/CompilerWarningLevelNotInCompliance.qlref
new file mode 100644
index 000000000..30fb98b63
--- /dev/null
+++ b/cpp/autosar/test/rules/A1-1-2.5/CompilerWarningLevelNotInCompliance.qlref
@@ -0,0 +1 @@
+rules/A1-1-2/CompilerWarningLevelNotInCompliance.ql
\ No newline at end of file
diff --git a/cpp/autosar/test/rules/A1-1-2.5/Wall-Wno-format.cpp b/cpp/autosar/test/rules/A1-1-2.5/Wall-Wno-format.cpp
new file mode 100644
index 000000000..93c4b9824
--- /dev/null
+++ b/cpp/autosar/test/rules/A1-1-2.5/Wall-Wno-format.cpp
@@ -0,0 +1,14 @@
+// semmle-extractor-options: --clang -std=c++14 -Wall -Wno-format
+// COMPLIANT
+
+// NOTE: When tested with `codeql test run`, the test extractor provides `-w`
+// which overrides `-Wcast-function-type` and causes this test case to be
+// non-compliant.
+//
+// However, when tested with our compiler matrix tests, this test db is built
+// via `codeql database create --command="..."`, and the `-w` flag will NOT be
+// used. This means the `-Wcast-function-type` flag is active and the test case
+// is compliant.
+//
+// Therefore, the .expected file for this test expects non-compliance, and the
+// .expected.gcc and .expected.clang files expect this test to be compliant.
diff --git a/cpp/autosar/test/rules/A1-1-2.5/options.clang b/cpp/autosar/test/rules/A1-1-2.5/options.clang
new file mode 100644
index 000000000..735817b68
--- /dev/null
+++ b/cpp/autosar/test/rules/A1-1-2.5/options.clang
@@ -0,0 +1 @@
+-Wall -Wno-format
\ No newline at end of file
diff --git a/cpp/autosar/test/rules/A1-1-2.5/options.gcc b/cpp/autosar/test/rules/A1-1-2.5/options.gcc
new file mode 100644
index 000000000..735817b68
--- /dev/null
+++ b/cpp/autosar/test/rules/A1-1-2.5/options.gcc
@@ -0,0 +1 @@
+-Wall -Wno-format
\ No newline at end of file
diff --git a/cpp/autosar/test/rules/A1-1-2.5/options.qcc b/cpp/autosar/test/rules/A1-1-2.5/options.qcc
new file mode 100644
index 000000000..735817b68
--- /dev/null
+++ b/cpp/autosar/test/rules/A1-1-2.5/options.qcc
@@ -0,0 +1 @@
+-Wall -Wno-format
\ No newline at end of file
diff --git a/cpp/autosar/test/rules/A1-1-2/CompilerWarningLevelNotInCompliance.expected b/cpp/autosar/test/rules/A1-1-2/CompilerWarningLevelNotInCompliance.expected
index 82ff1c0c3..ddc4e03f6 100644
--- a/cpp/autosar/test/rules/A1-1-2/CompilerWarningLevelNotInCompliance.expected
+++ b/cpp/autosar/test/rules/A1-1-2/CompilerWarningLevelNotInCompliance.expected
@@ -1 +1 @@
-| Wall.cpp:0:0:0:0 | Wall.cpp | No warning-level options were used in the compilation of 'Wall.cpp'. |
\ No newline at end of file
+| Wall.cpp:0:0:0:0 | Wall.cpp | No warning-level options were used in the compilation of 'Wall.cpp'. |