target_compile_options: Add syntax to specify shell strings

Options specified via `COMPILE_OPTIONS` and `INTERFACE_COMPILE_OPTIONS`
are deduplicated, but individual options can legitimately be duplicated
when grouped with other options, e.g.

    -D A -D B

After deduplication that becomes `-D A B`.  Therefore we need a way to
treat groups of options as units during deduplication.  A simple approach
is to specify each group as one option, e.g.

    "-D A" "-D B"

However, that conflicts with options that legitimately have spaces.  To
break this ambiguity, add a `SHELL:` prefix syntax to specify that an
option should be parsed like shell command line arguments after
deduplication, e.g.

    "SHELL:-D A" "SHELL:-D B"

These will survive deduplication intact, and then be parsed to produce
`-D A -D B` on the final command line.

Fixes: #15826

1 files changed, 25 insertions, 0 deletions

diff --git a/Tests/CompileOptions/main.cpp b/Tests/CompileOptions/main.cpp
index 63a0480..4779b88 100644
--- a/Tests/CompileOptions/main.cpp
+++ b/Tests/CompileOptions/main.cpp
@@ -12,6 +12,28 @@
 #endif
 #endif
 
+#ifndef NO_DEF_TESTS
+#ifndef DEF_A
+#error Expected definition DEF_A
+#endif
+
+#ifndef DEF_B
+#error Expected definition DEF_B
+#endif
+
+#ifndef DEF_C
+#error Expected definition DEF_C
+#endif
+
+#ifndef DEF_D
+#error Expected definition DEF_D
+#endif
+
+#ifndef DEF_STR
+#error Expected definition DEF_STR
+#endif
+#endif
+
 #include <string.h>
 
 int main()
@@ -20,6 +42,9 @@ int main()
 #ifdef TEST_OCTOTHORPE
           && strcmp(TEST_OCTOTHORPE, "#") == 0
 #endif
+#ifndef NO_DEF_TESTS
+          && strcmp(DEF_STR, "string with spaces") == 0
+#endif
           &&
           strcmp(EXPECTED_C_COMPILER_VERSION, TEST_C_COMPILER_VERSION) == 0 &&
           strcmp(EXPECTED_CXX_COMPILER_VERSION, TEST_CXX_COMPILER_VERSION) ==