[clang][Sema] Emit warnings about incorrect AVR interrupt/signal handlers

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -350,10 +350,11 @@ def warn_arm_interrupt_vfp_clobber : Warning<
   InGroup<DiagGroup<"arm-interrupt-vfp-clobber">>;
 def err_arm_interrupt_called : Error<
   "interrupt service routine cannot be called directly">;
-def warn_interrupt_attribute_invalid : Warning<
-   "%select{MIPS|MSP430|RISC-V}0 'interrupt' attribute only applies to "
-   "functions that have %select{no parameters|a 'void' return type}1">,
-   InGroup<IgnoredAttributes>;
+def warn_interrupt_signal_attribute_invalid : Warning<
+  "%select{MIPS|MSP430|RISC-V|AVR}0 '%select{interrupt|signal}1' "
+  "attribute only applies to functions that have "
+  "%select{no parameters|a 'void' return type}2">,
+  InGroup<IgnoredAttributes>;
 def warn_riscv_repeated_interrupt_attribute : Warning<
   "repeated RISC-V 'interrupt' attribute">, InGroup<IgnoredAttributes>;
 def note_riscv_repeated_interrupt_attribute : Note<

clang/lib/Sema/SemaAVR.cpp

@@ -30,6 +30,18 @@ void SemaAVR::handleInterruptAttr(Decl *D, const ParsedAttr &AL) {
   if (!AL.checkExactlyNumArgs(SemaRef, 0))
     return;
 
+  // AVR interrupt handlers must have no parameter and be void type.
+  if (hasFunctionProto(D) && getFunctionOrMethodNumParams(D) != 0) {
+    Diag(D->getLocation(), diag::warn_interrupt_signal_attribute_invalid)
+        << /*AVR*/ 3 << /*interrupt*/ 0 << 0;
+    return;
+  }
+  if (!getFunctionOrMethodResultType(D)->isVoidType()) {
+    Diag(D->getLocation(), diag::warn_interrupt_signal_attribute_invalid)
+        << /*AVR*/ 3 << /*interrupt*/ 0 << 1;
+    return;
+  }
+
   handleSimpleAttribute<AVRInterruptAttr>(*this, D, AL);
 }
 
@@ -43,6 +55,18 @@ void SemaAVR::handleSignalAttr(Decl *D, const ParsedAttr &AL) {
   if (!AL.checkExactlyNumArgs(SemaRef, 0))
     return;
 
+  // AVR signal handlers must have no parameter and be void type.
+  if (hasFunctionProto(D) && getFunctionOrMethodNumParams(D) != 0) {
+    Diag(D->getLocation(), diag::warn_interrupt_signal_attribute_invalid)
+        << /*AVR*/ 3 << /*signal*/ 1 << 0;
+    return;
+  }
+  if (!getFunctionOrMethodResultType(D)->isVoidType()) {
+    Diag(D->getLocation(), diag::warn_interrupt_signal_attribute_invalid)
+        << /*AVR*/ 3 << /*signal*/ 1 << 1;
+    return;
+  }
+
   handleSimpleAttribute<AVRSignalAttr>(*this, D, AL);
 }
 

clang/lib/Sema/SemaMIPS.cpp

@@ -271,14 +271,14 @@ void SemaMIPS::handleInterruptAttr(Decl *D, const ParsedAttr &AL) {
   }
 
   if (hasFunctionProto(D) && getFunctionOrMethodNumParams(D) != 0) {
-    Diag(D->getLocation(), diag::warn_interrupt_attribute_invalid)
-        << /*MIPS*/ 0 << 0;
+    Diag(D->getLocation(), diag::warn_interrupt_signal_attribute_invalid)
+        << /*MIPS*/ 0 << /*interrupt*/ 0 << 0;
     return;
   }
 
   if (!getFunctionOrMethodResultType(D)->isVoidType()) {
-    Diag(D->getLocation(), diag::warn_interrupt_attribute_invalid)
-        << /*MIPS*/ 0 << 1;
+    Diag(D->getLocation(), diag::warn_interrupt_signal_attribute_invalid)
+        << /*MIPS*/ 0 << /*interrupt*/ 0 << 1;
     return;
   }
 

clang/lib/Sema/SemaMSP430.cpp

@@ -32,14 +32,14 @@ void SemaMSP430::handleInterruptAttr(Decl *D, const ParsedAttr &AL) {
   }
 
   if (hasFunctionProto(D) && getFunctionOrMethodNumParams(D) != 0) {
-    Diag(D->getLocation(), diag::warn_interrupt_attribute_invalid)
-        << /*MSP430*/ 1 << 0;
+    Diag(D->getLocation(), diag::warn_interrupt_signal_attribute_invalid)
+        << /*MSP430*/ 1 << /*interrupt*/ 0 << 0;
     return;
   }
 
   if (!getFunctionOrMethodResultType(D)->isVoidType()) {
-    Diag(D->getLocation(), diag::warn_interrupt_attribute_invalid)
-        << /*MSP430*/ 1 << 1;
+    Diag(D->getLocation(), diag::warn_interrupt_signal_attribute_invalid)
+        << /*MSP430*/ 1 << /*interrupt*/ 0 << 1;
     return;
   }
 

clang/lib/Sema/SemaRISCV.cpp

@@ -1457,14 +1457,14 @@ void SemaRISCV::handleInterruptAttr(Decl *D, const ParsedAttr &AL) {
   }
 
   if (hasFunctionProto(D) && getFunctionOrMethodNumParams(D) != 0) {
-    Diag(D->getLocation(), diag::warn_interrupt_attribute_invalid)
-        << /*RISC-V*/ 2 << 0;
+    Diag(D->getLocation(), diag::warn_interrupt_signal_attribute_invalid)
+        << /*RISC-V*/ 2 << /*interrupt*/ 0 << 0;
     return;
   }
 
   if (!getFunctionOrMethodResultType(D)->isVoidType()) {
-    Diag(D->getLocation(), diag::warn_interrupt_attribute_invalid)
-        << /*RISC-V*/ 2 << 1;
+    Diag(D->getLocation(), diag::warn_interrupt_signal_attribute_invalid)
+        << /*RISC-V*/ 2 << /*interrupt*/ 0 << 1;
     return;
   }
 

clang/test/Sema/avr-interript-signal-attr.c

@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 %s -triple avr-unknown-unknown -verify -fsyntax-only
+struct a { int b; };
+
+struct a test __attribute__((interrupt)); // expected-warning {{'interrupt' attribute only applies to functions}}
+
+__attribute__((interrupt(12))) void foo(void) { } // expected-error {{'interrupt' attribute takes no arguments}}
+
+__attribute__((interrupt)) int fooa(void) { return 0; } // expected-warning {{'interrupt' attribute only applies to functions that have a 'void' return type}}
+
+__attribute__((interrupt)) void foob(int a) {} // expected-warning {{'interrupt' attribute only applies to functions that have no parameters}}
+
+__attribute__((signal)) int fooc(void) { return 0; } // expected-warning {{'signal' attribute only applies to functions that have a 'void' return type}}
+
+__attribute__((signal)) void food(int a) {} // expected-warning {{'signal' attribute only applies to functions that have no parameters}}
+
+__attribute__((interrupt)) void fooe(void) {}
+
+__attribute__((interrupt)) void foof() {}
+
+__attribute__((signal)) void foog(void) {}
+
+__attribute__((signal)) void fooh() {}