[clang-tools-extra] 09ed210 - [clang-tidy] Fix modernize-use-std-print check when return value used
Piotr Zegar via cfe-commits
cfe-commits at lists.llvm.org
Thu Jun 29 07:00:25 PDT 2023
Author: Mike Crowe
Date: 2023-06-29T14:00:08Z
New Revision: 09ed2102eab5d3d3786046009ff0d6724118b76b
URL: https://github.com/llvm/llvm-project/commit/09ed2102eab5d3d3786046009ff0d6724118b76b
DIFF: https://github.com/llvm/llvm-project/commit/09ed2102eab5d3d3786046009ff0d6724118b76b.diff
LOG: [clang-tidy] Fix modernize-use-std-print check when return value used
The initial implementation of the modernize-use-std-print check was
capable of converting calls to printf (etc.) which used the return value
to calls to std::print which has no return value, thus breaking the
code.
Use code inspired by the implementation of bugprone-unused-return-value
check to ignore cases where the return value is used. Add appropriate
lit test cases and documentation.
Reviewed By: PiotrZSL
Differential Revision: https://reviews.llvm.org/D153860
Added:
Modified:
clang-tools-extra/clang-tidy/modernize/UseStdPrintCheck.cpp
clang-tools-extra/docs/clang-tidy/checks/modernize/use-std-print.rst
clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print-absl.cpp
clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print-custom.cpp
clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print.cpp
Removed:
################################################################################
diff --git a/clang-tools-extra/clang-tidy/modernize/UseStdPrintCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseStdPrintCheck.cpp
index 9b368f9a3e6c94..b1e1189d4ed775 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseStdPrintCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseStdPrintCheck.cpp
@@ -70,27 +70,53 @@ void UseStdPrintCheck::registerPPCallbacks(const SourceManager &SM,
IncludeInserter.registerPreprocessor(PP);
}
+static clang::ast_matchers::StatementMatcher
+unusedReturnValue(clang::ast_matchers::StatementMatcher MatchedCallExpr) {
+ auto UnusedInCompoundStmt =
+ compoundStmt(forEach(MatchedCallExpr),
+ // The checker can't currently
diff erentiate between the
+ // return statement and other statements inside GNU statement
+ // expressions, so disable the checker inside them to avoid
+ // false positives.
+ unless(hasParent(stmtExpr())));
+ auto UnusedInIfStmt =
+ ifStmt(eachOf(hasThen(MatchedCallExpr), hasElse(MatchedCallExpr)));
+ auto UnusedInWhileStmt = whileStmt(hasBody(MatchedCallExpr));
+ auto UnusedInDoStmt = doStmt(hasBody(MatchedCallExpr));
+ auto UnusedInForStmt =
+ forStmt(eachOf(hasLoopInit(MatchedCallExpr),
+ hasIncrement(MatchedCallExpr), hasBody(MatchedCallExpr)));
+ auto UnusedInRangeForStmt = cxxForRangeStmt(hasBody(MatchedCallExpr));
+ auto UnusedInCaseStmt = switchCase(forEach(MatchedCallExpr));
+
+ return stmt(anyOf(UnusedInCompoundStmt, UnusedInIfStmt, UnusedInWhileStmt,
+ UnusedInDoStmt, UnusedInForStmt, UnusedInRangeForStmt,
+ UnusedInCaseStmt));
+}
+
void UseStdPrintCheck::registerMatchers(MatchFinder *Finder) {
if (!PrintfLikeFunctions.empty())
Finder->addMatcher(
- callExpr(argumentCountAtLeast(1),
- hasArgument(0, stringLiteral(isOrdinary())),
- callee(functionDecl(
- unless(cxxMethodDecl()),
- matchers::matchesAnyListedName(PrintfLikeFunctions))
- .bind("func_decl")))
- .bind("printf"),
+ unusedReturnValue(
+ callExpr(argumentCountAtLeast(1),
+ hasArgument(0, stringLiteral(isOrdinary())),
+ callee(functionDecl(unless(cxxMethodDecl()),
+ matchers::matchesAnyListedName(
+ PrintfLikeFunctions))
+ .bind("func_decl")))
+ .bind("printf")),
this);
if (!FprintfLikeFunctions.empty())
Finder->addMatcher(
- callExpr(argumentCountAtLeast(2),
- hasArgument(1, stringLiteral(isOrdinary())),
- callee(functionDecl(unless(cxxMethodDecl()),
- matchers::matchesAnyListedName(
- FprintfLikeFunctions))
- .bind("func_decl")))
- .bind("fprintf"),
+ unusedReturnValue(
+ callExpr(argumentCountAtLeast(2),
+ hasArgument(1, stringLiteral(isOrdinary())),
+ callee(functionDecl(unless(cxxMethodDecl()),
+ matchers::matchesAnyListedName(
+ FprintfLikeFunctions))
+ .bind("func_decl")))
+ .bind("fprintf")),
this);
}
diff --git a/clang-tools-extra/docs/clang-tidy/checks/modernize/use-std-print.rst b/clang-tools-extra/docs/clang-tidy/checks/modernize/use-std-print.rst
index 385ee35c4f8f8a..8034238bea90ef 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/modernize/use-std-print.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/modernize/use-std-print.rst
@@ -49,6 +49,13 @@ It doesn't do a bad job, but it's not perfect. In particular:
- The glibc extension ``%m``.
+- ``printf`` and similar functions return the number of characters printed.
+ ``std::print`` does not. This means that any invocations that use the
+ return value will not be converted. Unfortunately this currently includes
+ explicitly-casting to ``void``. Deficiencies in this check mean that any
+ invocations inside ``GCC`` compound statements cannot be converted even
+ if the resulting value is not used.
+
If conversion would be incomplete or unsafe then the entire invocation will
be left unchanged.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print-absl.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print-absl.cpp
index 53453800283093..dd22811cdaaf48 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print-absl.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print-absl.cpp
@@ -55,6 +55,12 @@ void printf_no_casts_in_strict_mode() {
// CHECK-FIXES: std::println("Unsigned integer {} from short", s);
}
+int printf_uses_return_value(int i) {
+ using namespace absl;
+
+ return PrintF("return value %d\n", i);
+}
+
void fprintf_simple(FILE *fp) {
absl::FPrintF(fp, "Hello %s %d", "world", 42);
// CHECK-MESSAGES: [[@LINE-1]]:3: warning: use 'std::print' instead of 'FPrintF' [modernize-use-std-print]
@@ -85,3 +91,9 @@ void fprintf_no_casts_in_strict_mode(FILE *fp) {
// CHECK-MESSAGES: [[@LINE-1]]:3: warning: use 'std::println' instead of 'FPrintF' [modernize-use-std-print]
// CHECK-FIXES: std::println(fp, "Unsigned integer {} from short", s);
}
+
+int fprintf_uses_return_value(FILE *fp, int i) {
+ using namespace absl;
+
+ return FPrintF(fp, "return value %d\n", i);
+}
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print-custom.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print-custom.cpp
index 08779837c75e73..a8dda40651b7b3 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print-custom.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print-custom.cpp
@@ -48,6 +48,12 @@ void printf_newline() {
printf("Hello %s %d\n", "world", 42);
}
+int printf_uses_return_value(int i) {
+ return myprintf("return value %d\n", i);
+ // CHECK-MESSAGES-NOT: [[@LINE-1]]:10: warning: use 'std::println' instead of 'myprintf' [modernize-use-std-print]
+ // CHECK-FIXES-NOT: std::println("return value {}", i);
+}
+
void fprintf_simple(FILE *fp)
{
myfprintf(stderr, "Hello %s %d", "world", 42);
@@ -73,3 +79,9 @@ void fprintf_newline(FILE *fp)
// When using custom options leave fprintf alone
fprintf(stderr, "Hello %s %d\n", "world", 42);
}
+
+int fprintf_uses_return_value(int i) {
+ return myfprintf(stderr, "return value %d\n", i);
+ // CHECK-MESSAGES-NOT: [[@LINE-1]]:10: warning: use 'std::println' instead of 'myprintf' [modernize-use-std-print]
+ // CHECK-FIXES-NOT: std::println(stderr, "return value {}", i);
+}
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print.cpp
index a40eec922ab558..437eb83055f43d 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print.cpp
@@ -1,11 +1,11 @@
// RUN: %check_clang_tidy -check-suffixes=,STRICT \
// RUN: -std=c++23 %s modernize-use-std-print %t -- \
// RUN: -config="{CheckOptions: [{key: StrictMode, value: true}]}" \
-// RUN: -- -isystem %clang_tidy_headers
+// RUN: -- -isystem %clang_tidy_headers -fexceptions
// RUN: %check_clang_tidy -check-suffixes=,NOTSTRICT \
// RUN: -std=c++23 %s modernize-use-std-print %t -- \
// RUN: -config="{CheckOptions: [{key: StrictMode, value: false}]}" \
-// RUN: -- -isystem %clang_tidy_headers
+// RUN: -- -isystem %clang_tidy_headers -fexceptions
#include <cstddef>
#include <cstdint>
#include <cstdio>
@@ -44,6 +44,239 @@ void printf_deceptive_newline() {
// CHECK-FIXES: std::println("Hello");
}
+// std::print returns nothing, so any callers that use the return
+// value cannot be automatically translated.
+int printf_uses_return_value(int choice) {
+ const int i = printf("Return value assigned to variable %d\n", 42);
+
+ extern void accepts_int(int);
+ accepts_int(printf("Return value passed to function %d\n", 42));
+
+ if (choice == 0)
+ printf("if body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println("if body {}", i);
+ else if (choice == 1)
+ printf("else if body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println("else if body {}", i);
+ else
+ printf("else body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println("else body {}", i);
+
+ if (printf("Return value used as boolean in if statement"))
+ if (printf("Return value used in expression if statement") == 44)
+ if (const int j = printf("Return value used in assignment in if statement"))
+ if (const int k = printf("Return value used with initializer in if statement"); k == 44)
+ ;
+
+ int d = 0;
+ while (printf("%d", d) < 2)
+ ++d;
+
+ while (true)
+ printf("while body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println("while body {}", i);
+
+ do
+ printf("do body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println("do body {}", i);
+ while (true);
+
+ for (;;)
+ printf("for body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println("for body {}", i);
+
+ for (printf("for init statement %d\n", i);;)
+ // CHECK-MESSAGES: [[@LINE-1]]:8: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println("for init statement {}", i);
+ ;;
+
+ for (int j = printf("for init statement %d\n", i);;)
+ ;;
+
+ for (; printf("for condition %d\n", i);)
+ ;;
+
+ for (;; printf("for expression %d\n", i))
+ // CHECK-MESSAGES: [[@LINE-1]]:11: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println("for expression {}", i)
+ ;;
+
+ for (auto C : "foo")
+ printf("ranged-for body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println("ranged-for body {}", i);
+
+ switch (1) {
+ case 1:
+ printf("switch case body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println("switch case body {}", i);
+ break;
+ default:
+ printf("switch default body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println("switch default body {}", i);
+ break;
+ }
+
+ try {
+ printf("try body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println("try body {}", i);
+ } catch (int) {
+ printf("catch body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println("catch body {}", i);
+ }
+
+ (printf("Parenthesised expression %d\n", i));
+ // CHECK-MESSAGES: [[@LINE-1]]:4: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: (std::println("Parenthesised expression {}", i));
+
+ // Ideally we would convert these two, but the current check doesn't cope with
+ // that.
+ (void)printf("cast to void %d\n", i);
+ // CHECK-MESSAGES-NOT: [[@LINE-1]]:9: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES-NOT: std::println("cast to void {}", i);
+
+ static_cast<void>(printf("static_cast to void %d\n", i));
+ // CHECK-MESSAGES-NOT: [[@LINE-1]]:9: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES-NOT: std::println("static cast to void {}", i);
+
+ const int x = ({ printf("GCC statement expression using return value immediately %d\n", i); });
+ const int y = ({ const int y = printf("GCC statement expression using return value immediately %d\n", i); y; });
+
+ // Ideally we would convert this one, but the current check doesn't cope with
+ // that.
+ ({ printf("GCC statement expression with unused result %d\n", i); });
+ // CHECK-MESSAGES-NOT: [[@LINE-1]]:6: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES-NOT: std::println("GCC statement expression with unused result {}", i);
+
+ return printf("Return value used in return\n");
+}
+
+int fprintf_uses_return_value(int choice) {
+ const int i = fprintf(stderr, "Return value assigned to variable %d\n", 42);
+
+ extern void accepts_int(int);
+ accepts_int(fprintf(stderr, "Return value passed to function %d\n", 42));
+
+ if (choice == 0)
+ fprintf(stderr, "if body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println(stderr, "if body {}", i);
+ else if (choice == 1)
+ fprintf(stderr, "else if body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println(stderr, "else if body {}", i);
+ else
+ fprintf(stderr, "else body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println(stderr, "else body {}", i);
+
+ if (fprintf(stderr, "Return value used as boolean in if statement"))
+ if (fprintf(stderr, "Return value used in expression if statement") == 44)
+ if (const int j = fprintf(stderr, "Return value used in assignment in if statement"))
+ if (const int k = fprintf(stderr, "Return value used with initializer in if statement"); k == 44)
+ ;
+
+ int d = 0;
+ while (fprintf(stderr, "%d", d) < 2)
+ ++d;
+
+ while (true)
+ fprintf(stderr, "while body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println(stderr, "while body {}", i);
+
+ do
+ fprintf(stderr, "do body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println(stderr, "do body {}", i);
+ while (true);
+
+ for (;;)
+ fprintf(stderr, "for body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println(stderr, "for body {}", i);
+
+ for (fprintf(stderr, "for init statement %d\n", i);;)
+ // CHECK-MESSAGES: [[@LINE-1]]:8: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println(stderr, "for init statement {}", i);
+ ;;
+
+ for (int j = fprintf(stderr, "for init statement %d\n", i);;)
+ ;;
+
+ for (; fprintf(stderr, "for condition %d\n", i);)
+ ;;
+
+ for (;; fprintf(stderr, "for expression %d\n", i))
+ // CHECK-MESSAGES: [[@LINE-1]]:11: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println(stderr, "for expression {}", i)
+ ;;
+
+ for (auto C : "foo")
+ fprintf(stderr, "ranged-for body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println(stderr, "ranged-for body {}", i);
+
+ switch (1) {
+ case 1:
+ fprintf(stderr, "switch case body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println(stderr, "switch case body {}", i);
+ break;
+ default:
+ fprintf(stderr, "switch default body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println(stderr, "switch default body {}", i);
+ break;
+ }
+
+ try {
+ fprintf(stderr, "try body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println(stderr, "try body {}", i);
+ } catch (int) {
+ fprintf(stderr, "catch body %d\n", i);
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES: std::println(stderr, "catch body {}", i);
+ }
+
+
+ (printf("Parenthesised expression %d\n", i));
+ // CHECK-MESSAGES: [[@LINE-1]]:4: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+ // CHECK-FIXES: (std::println("Parenthesised expression {}", i));
+
+ // Ideally we would convert these two, but the current check doesn't cope with
+ // that.
+ (void)fprintf(stderr, "cast to void %d\n", i);
+ // CHECK-MESSAGES-NOT: [[@LINE-1]]:9: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES-NOT: std::println(stderr, "cast to void {}", i);
+
+ static_cast<void>(fprintf(stderr, "static_cast to void %d\n", i));
+ // CHECK-MESSAGES-NOT: [[@LINE-1]]:9: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES-NOT: std::println(stderr, "static cast to void {}", i);
+
+ const int x = ({ fprintf(stderr, "GCC statement expression using return value immediately %d\n", i); });
+ const int y = ({ const int y = fprintf(stderr, "GCC statement expression using return value immediately %d\n", i); y; });
+
+ // Ideally we would convert this one, but the current check doesn't cope with
+ // that.
+ ({ fprintf(stderr, "GCC statement expression with unused result %d\n", i); });
+ // CHECK-MESSAGES-NOT: [[@LINE-1]]:6: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+ // CHECK-FIXES-NOT: std::println("GCC statement expression with unused result {}", i);
+
+ return fprintf(stderr, "Return value used in return\n");
+}
+
void fprintf_simple() {
fprintf(stderr, "Hello");
// CHECK-MESSAGES: [[@LINE-1]]:3: warning: use 'std::print' instead of 'fprintf' [modernize-use-std-print]
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