r373007 - [clang-scan-deps] Allow continuation line backslashes followed by whitespace

[Alex Lorenz via cfe-commits]

Author: arphaman
Date: Thu Sep 26 12:28:51 2019
New Revision: 373007

URL: http://llvm.org/viewvc/llvm-project?rev=373007&view=rev
Log:
[clang-scan-deps] Allow continuation line backslashes followed by whitespace
in the dependency source minimizer

Clang allows continuations that have whitespace between the backslash and the newline.
This patch ensures that the dependency source minimizer can handle the whitespace between
the backslash and the newline when looking for a line continuation.

Differential Revision: https://reviews.llvm.org/D68052

Modified:
    cfe/trunk/lib/Lex/DependencyDirectivesSourceMinimizer.cpp
    cfe/trunk/unittests/Lex/DependencyDirectivesSourceMinimizerTest.cpp

Modified: cfe/trunk/lib/Lex/DependencyDirectivesSourceMinimizer.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Lex/DependencyDirectivesSourceMinimizer.cpp?rev=373007&r1=373006&r2=373007&view=diff
==============================================================================
--- cfe/trunk/lib/Lex/DependencyDirectivesSourceMinimizer.cpp (original)
+++ cfe/trunk/lib/Lex/DependencyDirectivesSourceMinimizer.cpp Thu Sep 26 12:28:51 2019
@@ -244,14 +244,20 @@ static void skipToNewlineRaw(const char
   }
 }
 
-static const char *reverseOverSpaces(const char *First, const char *Last) {
+static const char *findLastNonSpace(const char *First, const char *Last) {
   assert(First <= Last);
-  const char *PrevLast = Last;
-  while (First != Last && isHorizontalWhitespace(Last[-1])) {
-    PrevLast = Last;
+  while (First != Last && isHorizontalWhitespace(Last[-1]))
     --Last;
-  }
-  return PrevLast;
+  return Last;
+}
+
+static const char *findFirstTrailingSpace(const char *First,
+                                          const char *Last) {
+  const char *LastNonSpace = findLastNonSpace(First, Last);
+  if (Last == LastNonSpace)
+    return Last;
+  assert(isHorizontalWhitespace(LastNonSpace[0]));
+  return LastNonSpace + 1;
 }
 
 static void skipLineComment(const char *&First, const char *const End) {
@@ -385,7 +391,7 @@ void Minimizer::printToNewline(const cha
       }
 
       // Deal with "//..." and "/*...*/".
-      append(First, reverseOverSpaces(First, Last));
+      append(First, findFirstTrailingSpace(First, Last));
       First = Last;
 
       if (Last[1] == '/') {
@@ -400,15 +406,20 @@ void Minimizer::printToNewline(const cha
     } while (Last != End && !isVerticalWhitespace(*Last));
 
     // Print out the string.
-    if (Last == End || Last == First || Last[-1] != '\\') {
-      append(First, reverseOverSpaces(First, Last));
+    const char *LastBeforeTrailingSpace = findLastNonSpace(First, Last);
+    if (Last == End || LastBeforeTrailingSpace == First ||
+        LastBeforeTrailingSpace[-1] != '\\') {
+      append(First, LastBeforeTrailingSpace);
       First = Last;
       skipNewline(First, End);
       return;
     }
 
-    // Print up to the backslash, backing up over spaces.
-    append(First, reverseOverSpaces(First, Last - 1));
+    // Print up to the backslash, backing up over spaces. Preserve at least one
+    // space, as the space matters when tokens are separated by a line
+    // continuation.
+    append(First, findFirstTrailingSpace(
+                      First, LastBeforeTrailingSpace - 1));
 
     First = Last;
     skipNewline(First, End);

Modified: cfe/trunk/unittests/Lex/DependencyDirectivesSourceMinimizerTest.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/unittests/Lex/DependencyDirectivesSourceMinimizerTest.cpp?rev=373007&r1=373006&r2=373007&view=diff
==============================================================================
--- cfe/trunk/unittests/Lex/DependencyDirectivesSourceMinimizerTest.cpp (original)
+++ cfe/trunk/unittests/Lex/DependencyDirectivesSourceMinimizerTest.cpp Thu Sep 26 12:28:51 2019
@@ -157,19 +157,19 @@ TEST(MinimizeSourceToDependencyDirective
 
   ASSERT_FALSE(minimizeSourceToDependencyDirectives(
       "#define MACRO(\t)\tcon \t tent\t", Out));
-  EXPECT_STREQ("#define MACRO() con \t tent\t\n", Out.data());
+  EXPECT_STREQ("#define MACRO() con \t tent\n", Out.data());
 
   ASSERT_FALSE(minimizeSourceToDependencyDirectives(
       "#define MACRO(\f)\fcon \f tent\f", Out));
-  EXPECT_STREQ("#define MACRO() con \f tent\f\n", Out.data());
+  EXPECT_STREQ("#define MACRO() con \f tent\n", Out.data());
 
   ASSERT_FALSE(minimizeSourceToDependencyDirectives(
       "#define MACRO(\v)\vcon \v tent\v", Out));
-  EXPECT_STREQ("#define MACRO() con \v tent\v\n", Out.data());
+  EXPECT_STREQ("#define MACRO() con \v tent\n", Out.data());
 
   ASSERT_FALSE(minimizeSourceToDependencyDirectives(
       "#define MACRO \t\v\f\v\t con\f\t\vtent\v\f \v", Out));
-  EXPECT_STREQ("#define MACRO con\f\t\vtent\v\n", Out.data());
+  EXPECT_STREQ("#define MACRO con\f\t\vtent\n", Out.data());
 }
 
 TEST(MinimizeSourceToDependencyDirectivesTest, DefineMultilineArgs) {
@@ -476,6 +476,17 @@ TEST(MinimizeSourceToDependencyDirective
   EXPECT_STREQ("#define GUA RD\n", Out.data());
 }
 
+TEST(MinimizeSourceToDependencyDirectivesTest,
+     WhitespaceAfterLineContinuationSlash) {
+  SmallVector<char, 128> Out;
+
+  ASSERT_FALSE(minimizeSourceToDependencyDirectives("#define A 1 + \\  \n"
+                                                    "2 + \\\t\n"
+                                                    "3\n",
+                                                    Out));
+  EXPECT_STREQ("#define A 1 + 2 + 3\n", Out.data());
+}
+
 TEST(MinimizeSourceToDependencyDirectivesTest, PoundWarningAndError) {
   SmallVector<char, 128> Out;