Author: Aaron Puchert Date: 2020-02-14T19:25:02+01:00 New Revision: 2f26bc5542705c390bf17af2fdfc31e056147ea9
URL: https://github.com/llvm/llvm-project/commit/2f26bc5542705c390bf17af2fdfc31e056147ea9 DIFF: https://github.com/llvm/llvm-project/commit/2f26bc5542705c390bf17af2fdfc31e056147ea9.diff LOG: Warn about zero-parameter K&R definitions in -Wstrict-prototypes Summary: Zero-parameter K&R definitions specify that the function has no parameters, but they are still not prototypes, so calling the function with the wrong number of parameters is just a warning, not an error. The C11 standard doesn't seem to directly define what a prototype is, but it can be inferred from 6.9.1p7: "If the declarator includes a parameter type list, the list also specifies the types of all the parameters; such a declarator also serves as a function prototype for later calls to the same function in the same translation unit." This refers to 6.7.6.3p5: "If, in the declaration “T D1”, D1 has the form D(parameter-type-list) or D(identifier-list_opt) [...]". Later in 6.11.7 it also refers only to the parameter-type-list variant as prototype: "The use of function definitions with separate parameter identifier and declaration lists (not prototype-format parameter type and identifier declarators) is an obsolescent feature." We already correctly treat an empty parameter list as non-prototype declaration, so we can just take that information. GCC also warns about this with -Wstrict-prototypes. This shouldn't affect C++, because there all FunctionType's are FunctionProtoTypes. I added a simple test for that. Reviewed By: aaron.ballman Differential Revision: https://reviews.llvm.org/D66919 Added: clang/test/Sema/warn-strict-prototypes.cpp Modified: clang/lib/Sema/SemaDecl.cpp clang/test/Sema/warn-strict-prototypes.c clang/test/Sema/warn-strict-prototypes.m Removed: ################################################################################ diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp index ff0bd939613c..4c088aa47f55 100644 --- a/clang/lib/Sema/SemaDecl.cpp +++ b/clang/lib/Sema/SemaDecl.cpp @@ -14154,11 +14154,7 @@ Decl *Sema::ActOnFinishFunctionBody(Decl *dcl, Stmt *Body, // Warn if K&R function is defined without a previous declaration. // This warning is issued only if the definition itself does not provide // a prototype. Only K&R definitions do not provide a prototype. - // An empty list in a function declarator that is part of a definition - // of that function specifies that the function has no parameters - // (C99 6.7.5.3p14) - if (!FD->hasWrittenPrototype() && FD->getNumParams() > 0 && - !LangOpts.CPlusPlus) { + if (!FD->hasWrittenPrototype()) { TypeSourceInfo *TI = FD->getTypeSourceInfo(); TypeLoc TL = TI->getTypeLoc(); FunctionTypeLoc FTL = TL.getAsAdjusted<FunctionTypeLoc>(); diff --git a/clang/test/Sema/warn-strict-prototypes.c b/clang/test/Sema/warn-strict-prototypes.c index 5565a09060fc..50b0f7d060f2 100644 --- a/clang/test/Sema/warn-strict-prototypes.c +++ b/clang/test/Sema/warn-strict-prototypes.c @@ -1,15 +1,18 @@ // RUN: %clang_cc1 -triple i386-pc-unknown -fsyntax-only -Wstrict-prototypes -Wno-implicit-function-declaration -verify %s // RUN: %clang_cc1 -triple i386-pc-unknown -fsyntax-only -Wstrict-prototypes -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s +// function definition with 0 params, no prototype, no preceding declaration. +void foo0() {} // expected-warning {{this old-style function definition is not preceded by a prototype}} + // function declaration with unspecified params void foo1(); // expected-warning {{this function declaration is not a prototype}} // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:11-[[@LINE-1]]:11}:"void" // function declaration with 0 params void foo2(void); -// function definition with 0 params(for both cases), -// valid according to 6.7.5.3/14 -void foo1() {} +// function definition with 0 params, no prototype. +void foo1() {} // expected-warning {{this old-style function definition is not preceded by a prototype}} +// function definition with 0 params, prototype. void foo2(void) {} // function type typedef unspecified params diff --git a/clang/test/Sema/warn-strict-prototypes.cpp b/clang/test/Sema/warn-strict-prototypes.cpp new file mode 100644 index 000000000000..6a3839ff9367 --- /dev/null +++ b/clang/test/Sema/warn-strict-prototypes.cpp @@ -0,0 +1,8 @@ +// RUN: %clang_cc1 -verify -fsyntax-only -Wstrict-prototypes %s +// expected-no-diagnostics + +void decl(); +void decl_void(void); + +void def() {} +void def_void(void) {} diff --git a/clang/test/Sema/warn-strict-prototypes.m b/clang/test/Sema/warn-strict-prototypes.m index 66d574f75f80..e2fde8ee38fc 100644 --- a/clang/test/Sema/warn-strict-prototypes.m +++ b/clang/test/Sema/warn-strict-prototypes.m @@ -10,7 +10,7 @@ @interface Foo @end -void foo() { +void foo() { // expected-warning {{this old-style function definition is not preceded by a prototype}} void (^block)() = // expected-warning {{this block declaration is not a prototype}} ^void(int arg) { // no warning }; _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits